intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

10 files changed, 11038 insertions, 0 deletions

diff --git a/contrib/libs/yaml/src/api.c b/contrib/libs/yaml/src/api.c
new file mode 100644
index 0000000000..16f88bd762
--- /dev/null
+++ b/contrib/libs/yaml/src/api.c
@@ -0,0 +1,1393 @@
+
+#include "yaml_private.h"
+
+/*
+ * Get the library version.
+ */
+
+YAML_DECLARE(const char *)
+yaml_get_version_string(void)
+{
+    return YAML_VERSION_STRING;
+}
+
+/*
+ * Get the library version numbers.
+ */
+
+YAML_DECLARE(void)
+yaml_get_version(int *major, int *minor, int *patch)
+{
+    *major = YAML_VERSION_MAJOR;
+    *minor = YAML_VERSION_MINOR;
+    *patch = YAML_VERSION_PATCH;
+}
+
+/*
+ * Allocate a dynamic memory block.
+ */
+
+YAML_DECLARE(void *)
+yaml_malloc(size_t size)
+{
+    return malloc(size ? size : 1);
+}
+
+/*
+ * Reallocate a dynamic memory block.
+ */
+
+YAML_DECLARE(void *)
+yaml_realloc(void *ptr, size_t size)
+{
+    return ptr ? realloc(ptr, size ? size : 1) : malloc(size ? size : 1);
+}
+
+/*
+ * Free a dynamic memory block.
+ */
+
+YAML_DECLARE(void)
+yaml_free(void *ptr)
+{
+    if (ptr) free(ptr);
+}
+
+/*
+ * Duplicate a string.
+ */
+
+YAML_DECLARE(yaml_char_t *)
+yaml_strdup(const yaml_char_t *str)
+{
+    if (!str)
+        return NULL;
+
+    return (yaml_char_t *)strdup((char *)str);
+}
+
+/*
+ * Extend a string.
+ */
+
+YAML_DECLARE(int)
+yaml_string_extend(yaml_char_t **start,
+        yaml_char_t **pointer, yaml_char_t **end)
+{
+    yaml_char_t *new_start = (yaml_char_t *)yaml_realloc((void*)*start, (*end - *start)*2);
+
+    if (!new_start) return 0;
+
+    memset(new_start + (*end - *start), 0, *end - *start);
+
+    *pointer = new_start + (*pointer - *start);
+    *end = new_start + (*end - *start)*2;
+    *start = new_start;
+
+    return 1;
+}
+
+/*
+ * Append a string B to a string A.
+ */
+
+YAML_DECLARE(int)
+yaml_string_join(
+        yaml_char_t **a_start, yaml_char_t **a_pointer, yaml_char_t **a_end,
+        yaml_char_t **b_start, yaml_char_t **b_pointer, SHIM(yaml_char_t **b_end))
+{
+    UNUSED_PARAM(b_end)
+    if (*b_start == *b_pointer)
+        return 1;
+
+    while (*a_end - *a_pointer <= *b_pointer - *b_start) {
+        if (!yaml_string_extend(a_start, a_pointer, a_end))
+            return 0;
+    }
+
+    memcpy(*a_pointer, *b_start, *b_pointer - *b_start);
+    *a_pointer += *b_pointer - *b_start;
+
+    return 1;
+}
+
+/*
+ * Extend a stack.
+ */
+
+YAML_DECLARE(int)
+yaml_stack_extend(void **start, void **top, void **end)
+{
+    void *new_start;
+
+    if ((char *)*end - (char *)*start >= INT_MAX / 2)
+	return 0;
+
+    new_start = yaml_realloc(*start, ((char *)*end - (char *)*start)*2);
+
+    if (!new_start) return 0;
+
+    *top = (char *)new_start + ((char *)*top - (char *)*start);
+    *end = (char *)new_start + ((char *)*end - (char *)*start)*2;
+    *start = new_start;
+
+    return 1;
+}
+
+/*
+ * Extend or move a queue.
+ */
+
+YAML_DECLARE(int)
+yaml_queue_extend(void **start, void **head, void **tail, void **end)
+{
+    /* Check if we need to resize the queue. */
+
+    if (*start == *head && *tail == *end) {
+        void *new_start = yaml_realloc(*start,
+                ((char *)*end - (char *)*start)*2);
+
+        if (!new_start) return 0;
+
+        *head = (char *)new_start + ((char *)*head - (char *)*start);
+        *tail = (char *)new_start + ((char *)*tail - (char *)*start);
+        *end = (char *)new_start + ((char *)*end - (char *)*start)*2;
+        *start = new_start;
+    }
+
+    /* Check if we need to move the queue at the beginning of the buffer. */
+
+    if (*tail == *end) {
+        if (*head != *tail) {
+            memmove(*start, *head, (char *)*tail - (char *)*head);
+        }
+        *tail = (char *)*tail - (char *)*head + (char *)*start;
+        *head = *start;
+    }
+
+    return 1;
+}
+
+
+/*
+ * Create a new parser object.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_initialize(yaml_parser_t *parser)
+{
+    assert(parser);     /* Non-NULL parser object expected. */
+
+    memset(parser, 0, sizeof(yaml_parser_t));
+    if (!BUFFER_INIT(parser, parser->raw_buffer, INPUT_RAW_BUFFER_SIZE))
+        goto error;
+    if (!BUFFER_INIT(parser, parser->buffer, INPUT_BUFFER_SIZE))
+        goto error;
+    if (!QUEUE_INIT(parser, parser->tokens, INITIAL_QUEUE_SIZE, yaml_token_t*))
+        goto error;
+    if (!STACK_INIT(parser, parser->indents, int*))
+        goto error;
+    if (!STACK_INIT(parser, parser->simple_keys, yaml_simple_key_t*))
+        goto error;
+    if (!STACK_INIT(parser, parser->states, yaml_parser_state_t*))
+        goto error;
+    if (!STACK_INIT(parser, parser->marks, yaml_mark_t*))
+        goto error;
+    if (!STACK_INIT(parser, parser->tag_directives, yaml_tag_directive_t*))
+        goto error;
+
+    return 1;
+
+error:
+
+    BUFFER_DEL(parser, parser->raw_buffer);
+    BUFFER_DEL(parser, parser->buffer);
+    QUEUE_DEL(parser, parser->tokens);
+    STACK_DEL(parser, parser->indents);
+    STACK_DEL(parser, parser->simple_keys);
+    STACK_DEL(parser, parser->states);
+    STACK_DEL(parser, parser->marks);
+    STACK_DEL(parser, parser->tag_directives);
+
+    return 0;
+}
+
+/*
+ * Destroy a parser object.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_delete(yaml_parser_t *parser)
+{
+    assert(parser); /* Non-NULL parser object expected. */
+
+    BUFFER_DEL(parser, parser->raw_buffer);
+    BUFFER_DEL(parser, parser->buffer);
+    while (!QUEUE_EMPTY(parser, parser->tokens)) {
+        yaml_token_delete(&DEQUEUE(parser, parser->tokens));
+    }
+    QUEUE_DEL(parser, parser->tokens);
+    STACK_DEL(parser, parser->indents);
+    STACK_DEL(parser, parser->simple_keys);
+    STACK_DEL(parser, parser->states);
+    STACK_DEL(parser, parser->marks);
+    while (!STACK_EMPTY(parser, parser->tag_directives)) {
+        yaml_tag_directive_t tag_directive = POP(parser, parser->tag_directives);
+        yaml_free(tag_directive.handle);
+        yaml_free(tag_directive.prefix);
+    }
+    STACK_DEL(parser, parser->tag_directives);
+
+    memset(parser, 0, sizeof(yaml_parser_t));
+}
+
+/*
+ * String read handler.
+ */
+
+static int
+yaml_string_read_handler(void *data, unsigned char *buffer, size_t size,
+        size_t *size_read)
+{
+    yaml_parser_t *parser = (yaml_parser_t *)data;
+
+    if (parser->input.string.current == parser->input.string.end) {
+        *size_read = 0;
+        return 1;
+    }
+
+    if (size > (size_t)(parser->input.string.end
+                - parser->input.string.current)) {
+        size = parser->input.string.end - parser->input.string.current;
+    }
+
+    memcpy(buffer, parser->input.string.current, size);
+    parser->input.string.current += size;
+    *size_read = size;
+    return 1;
+}
+
+/*
+ * File read handler.
+ */
+
+static int
+yaml_file_read_handler(void *data, unsigned char *buffer, size_t size,
+        size_t *size_read)
+{
+    yaml_parser_t *parser = (yaml_parser_t *)data;
+
+    *size_read = fread(buffer, 1, size, parser->input.file);
+    return !ferror(parser->input.file);
+}
+
+/*
+ * Set a string input.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_input_string(yaml_parser_t *parser,
+        const unsigned char *input, size_t size)
+{
+    assert(parser); /* Non-NULL parser object expected. */
+    assert(!parser->read_handler);  /* You can set the source only once. */
+    assert(input);  /* Non-NULL input string expected. */
+
+    parser->read_handler = yaml_string_read_handler;
+    parser->read_handler_data = parser;
+
+    parser->input.string.start = input;
+    parser->input.string.current = input;
+    parser->input.string.end = input+size;
+}
+
+/*
+ * Set a file input.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_input_file(yaml_parser_t *parser, FILE *file)
+{
+    assert(parser); /* Non-NULL parser object expected. */
+    assert(!parser->read_handler);  /* You can set the source only once. */
+    assert(file);   /* Non-NULL file object expected. */
+
+    parser->read_handler = yaml_file_read_handler;
+    parser->read_handler_data = parser;
+
+    parser->input.file = file;
+}
+
+/*
+ * Set a generic input.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_input(yaml_parser_t *parser,
+        yaml_read_handler_t *handler, void *data)
+{
+    assert(parser); /* Non-NULL parser object expected. */
+    assert(!parser->read_handler);  /* You can set the source only once. */
+    assert(handler);    /* Non-NULL read handler expected. */
+
+    parser->read_handler = handler;
+    parser->read_handler_data = data;
+}
+
+/*
+ * Set the source encoding.
+ */
+
+YAML_DECLARE(void)
+yaml_parser_set_encoding(yaml_parser_t *parser, yaml_encoding_t encoding)
+{
+    assert(parser); /* Non-NULL parser object expected. */
+    assert(!parser->encoding); /* Encoding is already set or detected. */
+
+    parser->encoding = encoding;
+}
+
+/*
+ * Create a new emitter object.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_initialize(yaml_emitter_t *emitter)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    memset(emitter, 0, sizeof(yaml_emitter_t));
+    if (!BUFFER_INIT(emitter, emitter->buffer, OUTPUT_BUFFER_SIZE))
+        goto error;
+    if (!BUFFER_INIT(emitter, emitter->raw_buffer, OUTPUT_RAW_BUFFER_SIZE))
+        goto error;
+    if (!STACK_INIT(emitter, emitter->states, yaml_emitter_state_t*))
+        goto error;
+    if (!QUEUE_INIT(emitter, emitter->events, INITIAL_QUEUE_SIZE, yaml_event_t*))
+        goto error;
+    if (!STACK_INIT(emitter, emitter->indents, int*))
+        goto error;
+    if (!STACK_INIT(emitter, emitter->tag_directives, yaml_tag_directive_t*))
+        goto error;
+
+    return 1;
+
+error:
+
+    BUFFER_DEL(emitter, emitter->buffer);
+    BUFFER_DEL(emitter, emitter->raw_buffer);
+    STACK_DEL(emitter, emitter->states);
+    QUEUE_DEL(emitter, emitter->events);
+    STACK_DEL(emitter, emitter->indents);
+    STACK_DEL(emitter, emitter->tag_directives);
+
+    return 0;
+}
+
+/*
+ * Destroy an emitter object.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_delete(yaml_emitter_t *emitter)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    BUFFER_DEL(emitter, emitter->buffer);
+    BUFFER_DEL(emitter, emitter->raw_buffer);
+    STACK_DEL(emitter, emitter->states);
+    while (!QUEUE_EMPTY(emitter, emitter->events)) {
+        yaml_event_delete(&DEQUEUE(emitter, emitter->events));
+    }
+    QUEUE_DEL(emitter, emitter->events);
+    STACK_DEL(emitter, emitter->indents);
+    while (!STACK_EMPTY(empty, emitter->tag_directives)) {
+        yaml_tag_directive_t tag_directive = POP(emitter, emitter->tag_directives);
+        yaml_free(tag_directive.handle);
+        yaml_free(tag_directive.prefix);
+    }
+    STACK_DEL(emitter, emitter->tag_directives);
+    yaml_free(emitter->anchors);
+
+    memset(emitter, 0, sizeof(yaml_emitter_t));
+}
+
+/*
+ * String write handler.
+ */
+
+static int
+yaml_string_write_handler(void *data, unsigned char *buffer, size_t size)
+{
+  yaml_emitter_t *emitter = (yaml_emitter_t *)data;
+
+    if (emitter->output.string.size - *emitter->output.string.size_written
+            < size) {
+        memcpy(emitter->output.string.buffer
+                + *emitter->output.string.size_written,
+                buffer,
+                emitter->output.string.size
+                - *emitter->output.string.size_written);
+        *emitter->output.string.size_written = emitter->output.string.size;
+        return 0;
+    }
+
+    memcpy(emitter->output.string.buffer
+            + *emitter->output.string.size_written, buffer, size);
+    *emitter->output.string.size_written += size;
+    return 1;
+}
+
+/*
+ * File write handler.
+ */
+
+static int
+yaml_file_write_handler(void *data, unsigned char *buffer, size_t size)
+{
+    yaml_emitter_t *emitter = (yaml_emitter_t *)data;
+
+    return (fwrite(buffer, 1, size, emitter->output.file) == size);
+}
+/*
+ * Set a string output.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_output_string(yaml_emitter_t *emitter,
+        unsigned char *output, size_t size, size_t *size_written)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+    assert(!emitter->write_handler);    /* You can set the output only once. */
+    assert(output);     /* Non-NULL output string expected. */
+
+    emitter->write_handler = yaml_string_write_handler;
+    emitter->write_handler_data = emitter;
+
+    emitter->output.string.buffer = output;
+    emitter->output.string.size = size;
+    emitter->output.string.size_written = size_written;
+    *size_written = 0;
+}
+
+/*
+ * Set a file output.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_output_file(yaml_emitter_t *emitter, FILE *file)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+    assert(!emitter->write_handler);    /* You can set the output only once. */
+    assert(file);       /* Non-NULL file object expected. */
+
+    emitter->write_handler = yaml_file_write_handler;
+    emitter->write_handler_data = emitter;
+
+    emitter->output.file = file;
+}
+
+/*
+ * Set a generic output handler.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_output(yaml_emitter_t *emitter,
+        yaml_write_handler_t *handler, void *data)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+    assert(!emitter->write_handler);    /* You can set the output only once. */
+    assert(handler);    /* Non-NULL handler object expected. */
+
+    emitter->write_handler = handler;
+    emitter->write_handler_data = data;
+}
+
+/*
+ * Set the output encoding.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_encoding(yaml_emitter_t *emitter, yaml_encoding_t encoding)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+    assert(!emitter->encoding);     /* You can set encoding only once. */
+
+    emitter->encoding = encoding;
+}
+
+/*
+ * Set the canonical output style.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_canonical(yaml_emitter_t *emitter, int canonical)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    emitter->canonical = (canonical != 0);
+}
+
+/*
+ * Set the indentation increment.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_indent(yaml_emitter_t *emitter, int indent)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    emitter->best_indent = (1 < indent && indent < 10) ? indent : 2;
+}
+
+/*
+ * Set the preferred line width.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_width(yaml_emitter_t *emitter, int width)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    emitter->best_width = (width >= 0) ? width : -1;
+}
+
+/*
+ * Set if unescaped non-ASCII characters are allowed.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_unicode(yaml_emitter_t *emitter, int unicode)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    emitter->unicode = (unicode != 0);
+}
+
+/*
+ * Set the preferred line break character.
+ */
+
+YAML_DECLARE(void)
+yaml_emitter_set_break(yaml_emitter_t *emitter, yaml_break_t line_break)
+{
+    assert(emitter);    /* Non-NULL emitter object expected. */
+
+    emitter->line_break = line_break;
+}
+
+/*
+ * Destroy a token object.
+ */
+
+YAML_DECLARE(void)
+yaml_token_delete(yaml_token_t *token)
+{
+    assert(token);  /* Non-NULL token object expected. */
+
+    switch (token->type)
+    {
+        case YAML_TAG_DIRECTIVE_TOKEN:
+            yaml_free(token->data.tag_directive.handle);
+            yaml_free(token->data.tag_directive.prefix);
+            break;
+
+        case YAML_ALIAS_TOKEN:
+            yaml_free(token->data.alias.value);
+            break;
+
+        case YAML_ANCHOR_TOKEN:
+            yaml_free(token->data.anchor.value);
+            break;
+
+        case YAML_TAG_TOKEN:
+            yaml_free(token->data.tag.handle);
+            yaml_free(token->data.tag.suffix);
+            break;
+
+        case YAML_SCALAR_TOKEN:
+            yaml_free(token->data.scalar.value);
+            break;
+
+        default:
+            break;
+    }
+
+    memset(token, 0, sizeof(yaml_token_t));
+}
+
+/*
+ * Check if a string is a valid UTF-8 sequence.
+ *
+ * Check 'reader.c' for more details on UTF-8 encoding.
+ */
+
+static int
+yaml_check_utf8(const yaml_char_t *start, size_t length)
+{
+    const yaml_char_t *end = start+length;
+    const yaml_char_t *pointer = start;
+
+    while (pointer < end) {
+        unsigned char octet;
+        unsigned int width;
+        unsigned int value;
+        size_t k;
+
+        octet = pointer[0];
+        width = (octet & 0x80) == 0x00 ? 1 :
+                (octet & 0xE0) == 0xC0 ? 2 :
+                (octet & 0xF0) == 0xE0 ? 3 :
+                (octet & 0xF8) == 0xF0 ? 4 : 0;
+        value = (octet & 0x80) == 0x00 ? octet & 0x7F :
+                (octet & 0xE0) == 0xC0 ? octet & 0x1F :
+                (octet & 0xF0) == 0xE0 ? octet & 0x0F :
+                (octet & 0xF8) == 0xF0 ? octet & 0x07 : 0;
+        if (!width) return 0;
+        if (pointer+width > end) return 0;
+        for (k = 1; k < width; k ++) {
+            octet = pointer[k];
+            if ((octet & 0xC0) != 0x80) return 0;
+            value = (value << 6) + (octet & 0x3F);
+        }
+        if (!((width == 1) ||
+            (width == 2 && value >= 0x80) ||
+            (width == 3 && value >= 0x800) ||
+            (width == 4 && value >= 0x10000))) return 0;
+
+        pointer += width;
+    }
+
+    return 1;
+}
+
+/*
+ * Create STREAM-START.
+ */
+
+YAML_DECLARE(int)
+yaml_stream_start_event_initialize(yaml_event_t *event,
+        yaml_encoding_t encoding)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(event);  /* Non-NULL event object is expected. */
+
+    STREAM_START_EVENT_INIT(*event, encoding, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Create STREAM-END.
+ */
+
+YAML_DECLARE(int)
+yaml_stream_end_event_initialize(yaml_event_t *event)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(event);  /* Non-NULL event object is expected. */
+
+    STREAM_END_EVENT_INIT(*event, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Create DOCUMENT-START.
+ */
+
+YAML_DECLARE(int)
+yaml_document_start_event_initialize(yaml_event_t *event,
+        yaml_version_directive_t *version_directive,
+        yaml_tag_directive_t *tag_directives_start,
+        yaml_tag_directive_t *tag_directives_end,
+        int implicit)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_version_directive_t *version_directive_copy = NULL;
+    struct {
+        yaml_tag_directive_t *start;
+        yaml_tag_directive_t *end;
+        yaml_tag_directive_t *top;
+    } tag_directives_copy = { NULL, NULL, NULL };
+    yaml_tag_directive_t value = { NULL, NULL };
+
+    assert(event);          /* Non-NULL event object is expected. */
+    assert((tag_directives_start && tag_directives_end) ||
+            (tag_directives_start == tag_directives_end));
+                            /* Valid tag directives are expected. */
+
+    if (version_directive) {
+        version_directive_copy = YAML_MALLOC_STATIC(yaml_version_directive_t);
+        if (!version_directive_copy) goto error;
+        version_directive_copy->major = version_directive->major;
+        version_directive_copy->minor = version_directive->minor;
+    }
+
+    if (tag_directives_start != tag_directives_end) {
+        yaml_tag_directive_t *tag_directive;
+        if (!STACK_INIT(&context, tag_directives_copy, yaml_tag_directive_t*))
+            goto error;
+        for (tag_directive = tag_directives_start;
+                tag_directive != tag_directives_end; tag_directive ++) {
+            assert(tag_directive->handle);
+            assert(tag_directive->prefix);
+            if (!yaml_check_utf8(tag_directive->handle,
+                        strlen((char *)tag_directive->handle)))
+                goto error;
+            if (!yaml_check_utf8(tag_directive->prefix,
+                        strlen((char *)tag_directive->prefix)))
+                goto error;
+            value.handle = yaml_strdup(tag_directive->handle);
+            value.prefix = yaml_strdup(tag_directive->prefix);
+            if (!value.handle || !value.prefix) goto error;
+            if (!PUSH(&context, tag_directives_copy, value))
+                goto error;
+            value.handle = NULL;
+            value.prefix = NULL;
+        }
+    }
+
+    DOCUMENT_START_EVENT_INIT(*event, version_directive_copy,
+            tag_directives_copy.start, tag_directives_copy.top,
+            implicit, mark, mark);
+
+    return 1;
+
+error:
+    yaml_free(version_directive_copy);
+    while (!STACK_EMPTY(context, tag_directives_copy)) {
+        yaml_tag_directive_t value = POP(context, tag_directives_copy);
+        yaml_free(value.handle);
+        yaml_free(value.prefix);
+    }
+    STACK_DEL(context, tag_directives_copy);
+    yaml_free(value.handle);
+    yaml_free(value.prefix);
+
+    return 0;
+}
+
+/*
+ * Create DOCUMENT-END.
+ */
+
+YAML_DECLARE(int)
+yaml_document_end_event_initialize(yaml_event_t *event, int implicit)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(event);      /* Non-NULL emitter object is expected. */
+
+    DOCUMENT_END_EVENT_INIT(*event, implicit, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Create ALIAS.
+ */
+
+YAML_DECLARE(int)
+yaml_alias_event_initialize(yaml_event_t *event, const yaml_char_t *anchor)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *anchor_copy = NULL;
+
+    assert(event);      /* Non-NULL event object is expected. */
+    assert(anchor);     /* Non-NULL anchor is expected. */
+
+    if (!yaml_check_utf8(anchor, strlen((char *)anchor))) return 0;
+
+    anchor_copy = yaml_strdup(anchor);
+    if (!anchor_copy)
+        return 0;
+
+    ALIAS_EVENT_INIT(*event, anchor_copy, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Create SCALAR.
+ */
+
+YAML_DECLARE(int)
+yaml_scalar_event_initialize(yaml_event_t *event,
+        const yaml_char_t *anchor, const yaml_char_t *tag,
+        const yaml_char_t *value, int length,
+        int plain_implicit, int quoted_implicit,
+        yaml_scalar_style_t style)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *anchor_copy = NULL;
+    yaml_char_t *tag_copy = NULL;
+    yaml_char_t *value_copy = NULL;
+
+    assert(event);      /* Non-NULL event object is expected. */
+    assert(value);      /* Non-NULL anchor is expected. */
+
+    if (anchor) {
+        if (!yaml_check_utf8(anchor, strlen((char *)anchor))) goto error;
+        anchor_copy = yaml_strdup(anchor);
+        if (!anchor_copy) goto error;
+    }
+
+    if (tag) {
+        if (!yaml_check_utf8(tag, strlen((char *)tag))) goto error;
+        tag_copy = yaml_strdup(tag);
+        if (!tag_copy) goto error;
+    }
+
+    if (length < 0) {
+        length = strlen((char *)value);
+    }
+
+    if (!yaml_check_utf8(value, length)) goto error;
+    value_copy = YAML_MALLOC(length+1);
+    if (!value_copy) goto error;
+    memcpy(value_copy, value, length);
+    value_copy[length] = '\0';
+
+    SCALAR_EVENT_INIT(*event, anchor_copy, tag_copy, value_copy, length,
+            plain_implicit, quoted_implicit, style, mark, mark);
+
+    return 1;
+
+error:
+    yaml_free(anchor_copy);
+    yaml_free(tag_copy);
+    yaml_free(value_copy);
+
+    return 0;
+}
+
+/*
+ * Create SEQUENCE-START.
+ */
+
+YAML_DECLARE(int)
+yaml_sequence_start_event_initialize(yaml_event_t *event,
+        const yaml_char_t *anchor, const yaml_char_t *tag, int implicit,
+        yaml_sequence_style_t style)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *anchor_copy = NULL;
+    yaml_char_t *tag_copy = NULL;
+
+    assert(event);      /* Non-NULL event object is expected. */
+
+    if (anchor) {
+        if (!yaml_check_utf8(anchor, strlen((char *)anchor))) goto error;
+        anchor_copy = yaml_strdup(anchor);
+        if (!anchor_copy) goto error;
+    }
+
+    if (tag) {
+        if (!yaml_check_utf8(tag, strlen((char *)tag))) goto error;
+        tag_copy = yaml_strdup(tag);
+        if (!tag_copy) goto error;
+    }
+
+    SEQUENCE_START_EVENT_INIT(*event, anchor_copy, tag_copy,
+            implicit, style, mark, mark);
+
+    return 1;
+
+error:
+    yaml_free(anchor_copy);
+    yaml_free(tag_copy);
+
+    return 0;
+}
+
+/*
+ * Create SEQUENCE-END.
+ */
+
+YAML_DECLARE(int)
+yaml_sequence_end_event_initialize(yaml_event_t *event)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(event);      /* Non-NULL event object is expected. */
+
+    SEQUENCE_END_EVENT_INIT(*event, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Create MAPPING-START.
+ */
+
+YAML_DECLARE(int)
+yaml_mapping_start_event_initialize(yaml_event_t *event,
+        const yaml_char_t *anchor, const yaml_char_t *tag, int implicit,
+        yaml_mapping_style_t style)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *anchor_copy = NULL;
+    yaml_char_t *tag_copy = NULL;
+
+    assert(event);      /* Non-NULL event object is expected. */
+
+    if (anchor) {
+        if (!yaml_check_utf8(anchor, strlen((char *)anchor))) goto error;
+        anchor_copy = yaml_strdup(anchor);
+        if (!anchor_copy) goto error;
+    }
+
+    if (tag) {
+        if (!yaml_check_utf8(tag, strlen((char *)tag))) goto error;
+        tag_copy = yaml_strdup(tag);
+        if (!tag_copy) goto error;
+    }
+
+    MAPPING_START_EVENT_INIT(*event, anchor_copy, tag_copy,
+            implicit, style, mark, mark);
+
+    return 1;
+
+error:
+    yaml_free(anchor_copy);
+    yaml_free(tag_copy);
+
+    return 0;
+}
+
+/*
+ * Create MAPPING-END.
+ */
+
+YAML_DECLARE(int)
+yaml_mapping_end_event_initialize(yaml_event_t *event)
+{
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(event);      /* Non-NULL event object is expected. */
+
+    MAPPING_END_EVENT_INIT(*event, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Destroy an event object.
+ */
+
+YAML_DECLARE(void)
+yaml_event_delete(yaml_event_t *event)
+{
+    yaml_tag_directive_t *tag_directive;
+
+    assert(event);  /* Non-NULL event object expected. */
+
+    switch (event->type)
+    {
+        case YAML_DOCUMENT_START_EVENT:
+            yaml_free(event->data.document_start.version_directive);
+            for (tag_directive = event->data.document_start.tag_directives.start;
+                    tag_directive != event->data.document_start.tag_directives.end;
+                    tag_directive++) {
+                yaml_free(tag_directive->handle);
+                yaml_free(tag_directive->prefix);
+            }
+            yaml_free(event->data.document_start.tag_directives.start);
+            break;
+
+        case YAML_ALIAS_EVENT:
+            yaml_free(event->data.alias.anchor);
+            break;
+
+        case YAML_SCALAR_EVENT:
+            yaml_free(event->data.scalar.anchor);
+            yaml_free(event->data.scalar.tag);
+            yaml_free(event->data.scalar.value);
+            break;
+
+        case YAML_SEQUENCE_START_EVENT:
+            yaml_free(event->data.sequence_start.anchor);
+            yaml_free(event->data.sequence_start.tag);
+            break;
+
+        case YAML_MAPPING_START_EVENT:
+            yaml_free(event->data.mapping_start.anchor);
+            yaml_free(event->data.mapping_start.tag);
+            break;
+
+        default:
+            break;
+    }
+
+    memset(event, 0, sizeof(yaml_event_t));
+}
+
+/*
+ * Create a document object.
+ */
+
+YAML_DECLARE(int)
+yaml_document_initialize(yaml_document_t *document,
+        yaml_version_directive_t *version_directive,
+        yaml_tag_directive_t *tag_directives_start,
+        yaml_tag_directive_t *tag_directives_end,
+        int start_implicit, int end_implicit)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+    struct {
+        yaml_node_t *start;
+        yaml_node_t *end;
+        yaml_node_t *top;
+    } nodes = { NULL, NULL, NULL };
+    yaml_version_directive_t *version_directive_copy = NULL;
+    struct {
+        yaml_tag_directive_t *start;
+        yaml_tag_directive_t *end;
+        yaml_tag_directive_t *top;
+    } tag_directives_copy = { NULL, NULL, NULL };
+    yaml_tag_directive_t value = { NULL, NULL };
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(document);       /* Non-NULL document object is expected. */
+    assert((tag_directives_start && tag_directives_end) ||
+            (tag_directives_start == tag_directives_end));
+                            /* Valid tag directives are expected. */
+
+    if (!STACK_INIT(&context, nodes, yaml_node_t*)) goto error;
+
+    if (version_directive) {
+        version_directive_copy = YAML_MALLOC_STATIC(yaml_version_directive_t);
+        if (!version_directive_copy) goto error;
+        version_directive_copy->major = version_directive->major;
+        version_directive_copy->minor = version_directive->minor;
+    }
+
+    if (tag_directives_start != tag_directives_end) {
+        yaml_tag_directive_t *tag_directive;
+        if (!STACK_INIT(&context, tag_directives_copy, yaml_tag_directive_t*))
+            goto error;
+        for (tag_directive = tag_directives_start;
+                tag_directive != tag_directives_end; tag_directive ++) {
+            assert(tag_directive->handle);
+            assert(tag_directive->prefix);
+            if (!yaml_check_utf8(tag_directive->handle,
+                        strlen((char *)tag_directive->handle)))
+                goto error;
+            if (!yaml_check_utf8(tag_directive->prefix,
+                        strlen((char *)tag_directive->prefix)))
+                goto error;
+            value.handle = yaml_strdup(tag_directive->handle);
+            value.prefix = yaml_strdup(tag_directive->prefix);
+            if (!value.handle || !value.prefix) goto error;
+            if (!PUSH(&context, tag_directives_copy, value))
+                goto error;
+            value.handle = NULL;
+            value.prefix = NULL;
+        }
+    }
+
+    DOCUMENT_INIT(*document, nodes.start, nodes.end, version_directive_copy,
+            tag_directives_copy.start, tag_directives_copy.top,
+            start_implicit, end_implicit, mark, mark);
+
+    return 1;
+
+error:
+    STACK_DEL(&context, nodes);
+    yaml_free(version_directive_copy);
+    while (!STACK_EMPTY(&context, tag_directives_copy)) {
+        yaml_tag_directive_t value = POP(&context, tag_directives_copy);
+        yaml_free(value.handle);
+        yaml_free(value.prefix);
+    }
+    STACK_DEL(&context, tag_directives_copy);
+    yaml_free(value.handle);
+    yaml_free(value.prefix);
+
+    return 0;
+}
+
+/*
+ * Destroy a document object.
+ */
+
+YAML_DECLARE(void)
+yaml_document_delete(yaml_document_t *document)
+{
+    yaml_tag_directive_t *tag_directive;
+
+    assert(document);   /* Non-NULL document object is expected. */
+
+    while (!STACK_EMPTY(&context, document->nodes)) {
+        yaml_node_t node = POP(&context, document->nodes);
+        yaml_free(node.tag);
+        switch (node.type) {
+            case YAML_SCALAR_NODE:
+                yaml_free(node.data.scalar.value);
+                break;
+            case YAML_SEQUENCE_NODE:
+                STACK_DEL(&context, node.data.sequence.items);
+                break;
+            case YAML_MAPPING_NODE:
+                STACK_DEL(&context, node.data.mapping.pairs);
+                break;
+            default:
+                assert(0);  /* Should not happen. */
+        }
+    }
+    STACK_DEL(&context, document->nodes);
+
+    yaml_free(document->version_directive);
+    for (tag_directive = document->tag_directives.start;
+            tag_directive != document->tag_directives.end;
+            tag_directive++) {
+        yaml_free(tag_directive->handle);
+        yaml_free(tag_directive->prefix);
+    }
+    yaml_free(document->tag_directives.start);
+
+    memset(document, 0, sizeof(yaml_document_t));
+}
+
+/**
+ * Get a document node.
+ */
+
+YAML_DECLARE(yaml_node_t *)
+yaml_document_get_node(yaml_document_t *document, int index)
+{
+    assert(document);   /* Non-NULL document object is expected. */
+
+    if (index > 0 && document->nodes.start + index <= document->nodes.top) {
+        return document->nodes.start + index - 1;
+    }
+    return NULL;
+}
+
+/**
+ * Get the root object.
+ */
+
+YAML_DECLARE(yaml_node_t *)
+yaml_document_get_root_node(yaml_document_t *document)
+{
+    assert(document);   /* Non-NULL document object is expected. */
+
+    if (document->nodes.top != document->nodes.start) {
+        return document->nodes.start;
+    }
+    return NULL;
+}
+
+/*
+ * Add a scalar node to a document.
+ */
+
+YAML_DECLARE(int)
+yaml_document_add_scalar(yaml_document_t *document,
+        const yaml_char_t *tag, const yaml_char_t *value, int length,
+        yaml_scalar_style_t style)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *tag_copy = NULL;
+    yaml_char_t *value_copy = NULL;
+    yaml_node_t node;
+
+    assert(document);   /* Non-NULL document object is expected. */
+    assert(value);      /* Non-NULL value is expected. */
+
+    if (!tag) {
+        tag = (yaml_char_t *)YAML_DEFAULT_SCALAR_TAG;
+    }
+
+    if (!yaml_check_utf8(tag, strlen((char *)tag))) goto error;
+    tag_copy = yaml_strdup(tag);
+    if (!tag_copy) goto error;
+
+    if (length < 0) {
+        length = strlen((char *)value);
+    }
+
+    if (!yaml_check_utf8(value, length)) goto error;
+    value_copy = YAML_MALLOC(length+1);
+    if (!value_copy) goto error;
+    memcpy(value_copy, value, length);
+    value_copy[length] = '\0';
+
+    SCALAR_NODE_INIT(node, tag_copy, value_copy, length, style, mark, mark);
+    if (!PUSH(&context, document->nodes, node)) goto error;
+
+    return document->nodes.top - document->nodes.start;
+
+error:
+    yaml_free(tag_copy);
+    yaml_free(value_copy);
+
+    return 0;
+}
+
+/*
+ * Add a sequence node to a document.
+ */
+
+YAML_DECLARE(int)
+yaml_document_add_sequence(yaml_document_t *document,
+        const yaml_char_t *tag, yaml_sequence_style_t style)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *tag_copy = NULL;
+    struct {
+        yaml_node_item_t *start;
+        yaml_node_item_t *end;
+        yaml_node_item_t *top;
+    } items = { NULL, NULL, NULL };
+    yaml_node_t node;
+
+    assert(document);   /* Non-NULL document object is expected. */
+
+    if (!tag) {
+        tag = (yaml_char_t *)YAML_DEFAULT_SEQUENCE_TAG;
+    }
+
+    if (!yaml_check_utf8(tag, strlen((char *)tag))) goto error;
+    tag_copy = yaml_strdup(tag);
+    if (!tag_copy) goto error;
+
+    if (!STACK_INIT(&context, items, yaml_node_item_t*)) goto error;
+
+    SEQUENCE_NODE_INIT(node, tag_copy, items.start, items.end,
+            style, mark, mark);
+    if (!PUSH(&context, document->nodes, node)) goto error;
+
+    return document->nodes.top - document->nodes.start;
+
+error:
+    STACK_DEL(&context, items);
+    yaml_free(tag_copy);
+
+    return 0;
+}
+
+/*
+ * Add a mapping node to a document.
+ */
+
+YAML_DECLARE(int)
+yaml_document_add_mapping(yaml_document_t *document,
+        const yaml_char_t *tag, yaml_mapping_style_t style)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+    yaml_mark_t mark = { 0, 0, 0 };
+    yaml_char_t *tag_copy = NULL;
+    struct {
+        yaml_node_pair_t *start;
+        yaml_node_pair_t *end;
+        yaml_node_pair_t *top;
+    } pairs = { NULL, NULL, NULL };
+    yaml_node_t node;
+
+    assert(document);   /* Non-NULL document object is expected. */
+
+    if (!tag) {
+        tag = (yaml_char_t *)YAML_DEFAULT_MAPPING_TAG;
+    }
+
+    if (!yaml_check_utf8(tag, strlen((char *)tag))) goto error;
+    tag_copy = yaml_strdup(tag);
+    if (!tag_copy) goto error;
+
+    if (!STACK_INIT(&context, pairs, yaml_node_pair_t*)) goto error;
+
+    MAPPING_NODE_INIT(node, tag_copy, pairs.start, pairs.end,
+            style, mark, mark);
+    if (!PUSH(&context, document->nodes, node)) goto error;
+
+    return document->nodes.top - document->nodes.start;
+
+error:
+    STACK_DEL(&context, pairs);
+    yaml_free(tag_copy);
+
+    return 0;
+}
+
+/*
+ * Append an item to a sequence node.
+ */
+
+YAML_DECLARE(int)
+yaml_document_append_sequence_item(yaml_document_t *document,
+        int sequence, int item)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+
+    assert(document);       /* Non-NULL document is required. */
+    assert(sequence > 0
+            && document->nodes.start + sequence <= document->nodes.top);
+                            /* Valid sequence id is required. */
+    assert(document->nodes.start[sequence-1].type == YAML_SEQUENCE_NODE);
+                            /* A sequence node is required. */
+    assert(item > 0 && document->nodes.start + item <= document->nodes.top);
+                            /* Valid item id is required. */
+
+    if (!PUSH(&context,
+                document->nodes.start[sequence-1].data.sequence.items, item))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Append a pair of a key and a value to a mapping node.
+ */
+
+YAML_DECLARE(int)
+yaml_document_append_mapping_pair(yaml_document_t *document,
+        int mapping, int key, int value)
+{
+    struct {
+        yaml_error_type_t error;
+    } context;
+
+    yaml_node_pair_t pair;
+
+    assert(document);       /* Non-NULL document is required. */
+    assert(mapping > 0
+            && document->nodes.start + mapping <= document->nodes.top);
+                            /* Valid mapping id is required. */
+    assert(document->nodes.start[mapping-1].type == YAML_MAPPING_NODE);
+                            /* A mapping node is required. */
+    assert(key > 0 && document->nodes.start + key <= document->nodes.top);
+                            /* Valid key id is required. */
+    assert(value > 0 && document->nodes.start + value <= document->nodes.top);
+                            /* Valid value id is required. */
+
+    pair.key = key;
+    pair.value = value;
+
+    if (!PUSH(&context,
+                document->nodes.start[mapping-1].data.mapping.pairs, pair))
+        return 0;
+
+    return 1;
+}
+
+
diff --git a/contrib/libs/yaml/src/config.h b/contrib/libs/yaml/src/config.h
new file mode 100644
index 0000000000..22a2296e5e
--- /dev/null
+++ b/contrib/libs/yaml/src/config.h
@@ -0,0 +1,82 @@
+/* include/config.h.  Generated from config.h.in by configure.  */
+/* include/config.h.in.  Generated from configure.ac by autoheader.  */
+
+/* Define to 1 if you have the <dlfcn.h> header file. */
+#define HAVE_DLFCN_H 1
+
+/* Define to 1 if you have the <inttypes.h> header file. */
+#define HAVE_INTTYPES_H 1
+
+/* Define to 1 if you have the <stdint.h> header file. */
+#define HAVE_STDINT_H 1
+
+/* Define to 1 if you have the <stdio.h> header file. */
+#define HAVE_STDIO_H 1
+
+/* Define to 1 if you have the <stdlib.h> header file. */
+#define HAVE_STDLIB_H 1
+
+/* Define to 1 if you have the <strings.h> header file. */
+#define HAVE_STRINGS_H 1
+
+/* Define to 1 if you have the <string.h> header file. */
+#define HAVE_STRING_H 1
+
+/* Define to 1 if you have the <sys/stat.h> header file. */
+#define HAVE_SYS_STAT_H 1
+
+/* Define to 1 if you have the <sys/types.h> header file. */
+#define HAVE_SYS_TYPES_H 1
+
+/* Define to 1 if you have the <unistd.h> header file. */
+#define HAVE_UNISTD_H 1
+
+/* Define to the sub-directory where libtool stores uninstalled libraries. */
+#define LT_OBJDIR ".libs/"
+
+/* Name of package */
+#define PACKAGE "yaml"
+
+/* Define to the address where bug reports for this package should be sent. */
+#define PACKAGE_BUGREPORT "https://github.com/yaml/libyaml/issues/new"
+
+/* Define to the full name of this package. */
+#define PACKAGE_NAME "yaml"
+
+/* Define to the full name and version of this package. */
+#define PACKAGE_STRING "yaml 0.2.5"
+
+/* Define to the one symbol short name of this package. */
+#define PACKAGE_TARNAME "yaml"
+
+/* Define to the home page for this package. */
+#define PACKAGE_URL ""
+
+/* Define to the version of this package. */
+#define PACKAGE_VERSION "0.2.5"
+
+/* Define to 1 if all of the C90 standard headers exist (not just the ones
+   required in a freestanding environment). This macro is provided for
+   backward compatibility; new code need not use it. */
+#define STDC_HEADERS 1
+
+/* Version number of package */
+#define VERSION "0.2.5"
+
+/* Define the major version number. */
+#define YAML_VERSION_MAJOR 0
+
+/* Define the minor version number. */
+#define YAML_VERSION_MINOR 2
+
+/* Define the patch version number. */
+#define YAML_VERSION_PATCH 5
+
+/* Define the version string. */
+#define YAML_VERSION_STRING "0.2.5"
+
+/* Define to empty if `const' does not conform to ANSI C. */
+/* #undef const */
+
+/* Define to `unsigned int' if <sys/types.h> does not define. */
+/* #undef size_t */
diff --git a/contrib/libs/yaml/src/dumper.c b/contrib/libs/yaml/src/dumper.c
new file mode 100644
index 0000000000..1fe940b674
--- /dev/null
+++ b/contrib/libs/yaml/src/dumper.c
@@ -0,0 +1,394 @@
+
+#include "yaml_private.h"
+
+/*
+ * API functions.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_open(yaml_emitter_t *emitter);
+
+YAML_DECLARE(int)
+yaml_emitter_close(yaml_emitter_t *emitter);
+
+YAML_DECLARE(int)
+yaml_emitter_dump(yaml_emitter_t *emitter, yaml_document_t *document);
+
+/*
+ * Clean up functions.
+ */
+
+static void
+yaml_emitter_delete_document_and_anchors(yaml_emitter_t *emitter);
+
+/*
+ * Anchor functions.
+ */
+
+static void
+yaml_emitter_anchor_node(yaml_emitter_t *emitter, int index);
+
+static yaml_char_t *
+yaml_emitter_generate_anchor(yaml_emitter_t *emitter, int anchor_id);
+
+
+/*
+ * Serialize functions.
+ */
+
+static int
+yaml_emitter_dump_node(yaml_emitter_t *emitter, int index);
+
+static int
+yaml_emitter_dump_alias(yaml_emitter_t *emitter, yaml_char_t *anchor);
+
+static int
+yaml_emitter_dump_scalar(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor);
+
+static int
+yaml_emitter_dump_sequence(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor);
+
+static int
+yaml_emitter_dump_mapping(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor);
+
+/*
+ * Issue a STREAM-START event.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_open(yaml_emitter_t *emitter)
+{
+    yaml_event_t event;
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(emitter);            /* Non-NULL emitter object is required. */
+    assert(!emitter->opened);   /* Emitter should not be opened yet. */
+
+    STREAM_START_EVENT_INIT(event, YAML_ANY_ENCODING, mark, mark);
+
+    if (!yaml_emitter_emit(emitter, &event)) {
+        return 0;
+    }
+
+    emitter->opened = 1;
+
+    return 1;
+}
+
+/*
+ * Issue a STREAM-END event.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_close(yaml_emitter_t *emitter)
+{
+    yaml_event_t event;
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(emitter);            /* Non-NULL emitter object is required. */
+    assert(emitter->opened);    /* Emitter should be opened. */
+
+    if (emitter->closed) return 1;
+
+    STREAM_END_EVENT_INIT(event, mark, mark);
+
+    if (!yaml_emitter_emit(emitter, &event)) {
+        return 0;
+    }
+
+    emitter->closed = 1;
+
+    return 1;
+}
+
+/*
+ * Dump a YAML document.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_dump(yaml_emitter_t *emitter, yaml_document_t *document)
+{
+    yaml_event_t event;
+    yaml_mark_t mark = { 0, 0, 0 };
+
+    assert(emitter);            /* Non-NULL emitter object is required. */
+    assert(document);           /* Non-NULL emitter object is expected. */
+
+    emitter->document = document;
+
+    if (!emitter->opened) {
+        if (!yaml_emitter_open(emitter)) goto error;
+    }
+
+    if (STACK_EMPTY(emitter, document->nodes)) {
+        if (!yaml_emitter_close(emitter)) goto error;
+        yaml_emitter_delete_document_and_anchors(emitter);
+        return 1;
+    }
+
+    assert(emitter->opened);    /* Emitter should be opened. */
+
+    emitter->anchors = (yaml_anchors_t*)yaml_malloc(sizeof(*(emitter->anchors))
+            * (document->nodes.top - document->nodes.start));
+    if (!emitter->anchors) goto error;
+    memset(emitter->anchors, 0, sizeof(*(emitter->anchors))
+            * (document->nodes.top - document->nodes.start));
+
+    DOCUMENT_START_EVENT_INIT(event, document->version_directive,
+            document->tag_directives.start, document->tag_directives.end,
+            document->start_implicit, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) goto error;
+
+    yaml_emitter_anchor_node(emitter, 1);
+    if (!yaml_emitter_dump_node(emitter, 1)) goto error;
+
+    DOCUMENT_END_EVENT_INIT(event, document->end_implicit, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) goto error;
+
+    yaml_emitter_delete_document_and_anchors(emitter);
+
+    return 1;
+
+error:
+
+    yaml_emitter_delete_document_and_anchors(emitter);
+
+    return 0;
+}
+
+/*
+ * Clean up the emitter object after a document is dumped.
+ */
+
+static void
+yaml_emitter_delete_document_and_anchors(yaml_emitter_t *emitter)
+{
+    int index;
+
+    if (!emitter->anchors) {
+        yaml_document_delete(emitter->document);
+        emitter->document = NULL;
+        return;
+    }
+
+    for (index = 0; emitter->document->nodes.start + index
+            < emitter->document->nodes.top; index ++) {
+        yaml_node_t node = emitter->document->nodes.start[index];
+        if (!emitter->anchors[index].serialized) {
+            yaml_free(node.tag);
+            if (node.type == YAML_SCALAR_NODE) {
+                yaml_free(node.data.scalar.value);
+            }
+        }
+        if (node.type == YAML_SEQUENCE_NODE) {
+            STACK_DEL(emitter, node.data.sequence.items);
+        }
+        if (node.type == YAML_MAPPING_NODE) {
+            STACK_DEL(emitter, node.data.mapping.pairs);
+        }
+    }
+
+    STACK_DEL(emitter, emitter->document->nodes);
+    yaml_free(emitter->anchors);
+
+    emitter->anchors = NULL;
+    emitter->last_anchor_id = 0;
+    emitter->document = NULL;
+}
+
+/*
+ * Check the references of a node and assign the anchor id if needed.
+ */
+
+static void
+yaml_emitter_anchor_node(yaml_emitter_t *emitter, int index)
+{
+    yaml_node_t *node = emitter->document->nodes.start + index - 1;
+    yaml_node_item_t *item;
+    yaml_node_pair_t *pair;
+
+    emitter->anchors[index-1].references ++;
+
+    if (emitter->anchors[index-1].references == 1) {
+        switch (node->type) {
+            case YAML_SEQUENCE_NODE:
+                for (item = node->data.sequence.items.start;
+                        item < node->data.sequence.items.top; item ++) {
+                    yaml_emitter_anchor_node(emitter, *item);
+                }
+                break;
+            case YAML_MAPPING_NODE:
+                for (pair = node->data.mapping.pairs.start;
+                        pair < node->data.mapping.pairs.top; pair ++) {
+                    yaml_emitter_anchor_node(emitter, pair->key);
+                    yaml_emitter_anchor_node(emitter, pair->value);
+                }
+                break;
+            default:
+                break;
+        }
+    }
+
+    else if (emitter->anchors[index-1].references == 2) {
+        emitter->anchors[index-1].anchor = (++ emitter->last_anchor_id);
+    }
+}
+
+/*
+ * Generate a textual representation for an anchor.
+ */
+
+#define ANCHOR_TEMPLATE         "id%03d"
+#define ANCHOR_TEMPLATE_LENGTH  16
+
+static yaml_char_t *
+yaml_emitter_generate_anchor(SHIM(yaml_emitter_t *emitter), int anchor_id)
+{
+    yaml_char_t *anchor = YAML_MALLOC(ANCHOR_TEMPLATE_LENGTH);
+
+    if (!anchor) return NULL;
+
+    sprintf((char *)anchor, ANCHOR_TEMPLATE, anchor_id);
+
+    return anchor;
+}
+
+/*
+ * Serialize a node.
+ */
+
+static int
+yaml_emitter_dump_node(yaml_emitter_t *emitter, int index)
+{
+    yaml_node_t *node = emitter->document->nodes.start + index - 1;
+    int anchor_id = emitter->anchors[index-1].anchor;
+    yaml_char_t *anchor = NULL;
+
+    if (anchor_id) {
+        anchor = yaml_emitter_generate_anchor(emitter, anchor_id);
+        if (!anchor) return 0;
+    }
+
+    if (emitter->anchors[index-1].serialized) {
+        return yaml_emitter_dump_alias(emitter, anchor);
+    }
+
+    emitter->anchors[index-1].serialized = 1;
+
+    switch (node->type) {
+        case YAML_SCALAR_NODE:
+            return yaml_emitter_dump_scalar(emitter, node, anchor);
+        case YAML_SEQUENCE_NODE:
+            return yaml_emitter_dump_sequence(emitter, node, anchor);
+        case YAML_MAPPING_NODE:
+            return yaml_emitter_dump_mapping(emitter, node, anchor);
+        default:
+            assert(0);      /* Could not happen. */
+            break;
+    }
+
+    return 0;       /* Could not happen. */
+}
+
+/*
+ * Serialize an alias.
+ */
+
+static int
+yaml_emitter_dump_alias(yaml_emitter_t *emitter, yaml_char_t *anchor)
+{
+    yaml_event_t event;
+    yaml_mark_t mark  = { 0, 0, 0 };
+
+    ALIAS_EVENT_INIT(event, anchor, mark, mark);
+
+    return yaml_emitter_emit(emitter, &event);
+}
+
+/*
+ * Serialize a scalar.
+ */
+
+static int
+yaml_emitter_dump_scalar(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor)
+{
+    yaml_event_t event;
+    yaml_mark_t mark  = { 0, 0, 0 };
+
+    int plain_implicit = (strcmp((char *)node->tag,
+                YAML_DEFAULT_SCALAR_TAG) == 0);
+    int quoted_implicit = (strcmp((char *)node->tag,
+                YAML_DEFAULT_SCALAR_TAG) == 0);
+
+    SCALAR_EVENT_INIT(event, anchor, node->tag, node->data.scalar.value,
+            node->data.scalar.length, plain_implicit, quoted_implicit,
+            node->data.scalar.style, mark, mark);
+
+    return yaml_emitter_emit(emitter, &event);
+}
+
+/*
+ * Serialize a sequence.
+ */
+
+static int
+yaml_emitter_dump_sequence(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor)
+{
+    yaml_event_t event;
+    yaml_mark_t mark  = { 0, 0, 0 };
+
+    int implicit = (strcmp((char *)node->tag, YAML_DEFAULT_SEQUENCE_TAG) == 0);
+
+    yaml_node_item_t *item;
+
+    SEQUENCE_START_EVENT_INIT(event, anchor, node->tag, implicit,
+            node->data.sequence.style, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) return 0;
+
+    for (item = node->data.sequence.items.start;
+            item < node->data.sequence.items.top; item ++) {
+        if (!yaml_emitter_dump_node(emitter, *item)) return 0;
+    }
+
+    SEQUENCE_END_EVENT_INIT(event, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) return 0;
+
+    return 1;
+}
+
+/*
+ * Serialize a mapping.
+ */
+
+static int
+yaml_emitter_dump_mapping(yaml_emitter_t *emitter, yaml_node_t *node,
+        yaml_char_t *anchor)
+{
+    yaml_event_t event;
+    yaml_mark_t mark  = { 0, 0, 0 };
+
+    int implicit = (strcmp((char *)node->tag, YAML_DEFAULT_MAPPING_TAG) == 0);
+
+    yaml_node_pair_t *pair;
+
+    MAPPING_START_EVENT_INIT(event, anchor, node->tag, implicit,
+            node->data.mapping.style, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) return 0;
+
+    for (pair = node->data.mapping.pairs.start;
+            pair < node->data.mapping.pairs.top; pair ++) {
+        if (!yaml_emitter_dump_node(emitter, pair->key)) return 0;
+        if (!yaml_emitter_dump_node(emitter, pair->value)) return 0;
+    }
+
+    MAPPING_END_EVENT_INIT(event, mark, mark);
+    if (!yaml_emitter_emit(emitter, &event)) return 0;
+
+    return 1;
+}
+
diff --git a/contrib/libs/yaml/src/emitter.c b/contrib/libs/yaml/src/emitter.c
new file mode 100644
index 0000000000..609b28a4c6
--- /dev/null
+++ b/contrib/libs/yaml/src/emitter.c
@@ -0,0 +1,2358 @@
+
+#include "yaml_private.h"
+
+/*
+ * Flush the buffer if needed.
+ */
+
+#define FLUSH(emitter)                                                          \
+    ((emitter->buffer.pointer+5 < emitter->buffer.end)                          \
+     || yaml_emitter_flush(emitter))
+
+/*
+ * Put a character to the output buffer.
+ */
+
+#define PUT(emitter,value)                                                      \
+    (FLUSH(emitter)                                                             \
+     && (*(emitter->buffer.pointer++) = (yaml_char_t)(value),                   \
+         emitter->column++,                                             	\
+         1))
+
+/*
+ * Put a line break to the output buffer.
+ */
+
+#define PUT_BREAK(emitter)                                                      \
+    (FLUSH(emitter)                                                             \
+     && ((emitter->line_break == YAML_CR_BREAK ?                                \
+             (*(emitter->buffer.pointer++) = (yaml_char_t) '\r') :              \
+          emitter->line_break == YAML_LN_BREAK ?                                \
+             (*(emitter->buffer.pointer++) = (yaml_char_t) '\n') :              \
+          emitter->line_break == YAML_CRLN_BREAK ?                              \
+             (*(emitter->buffer.pointer++) = (yaml_char_t) '\r',                \
+              *(emitter->buffer.pointer++) = (yaml_char_t) '\n') : 0),          \
+         emitter->column = 0,                                                   \
+         emitter->line ++,                                                      \
+         1))
+
+/*
+ * Copy a character from a string into buffer.
+ */
+
+#define WRITE(emitter,string)                                                   \
+    (FLUSH(emitter)                                                             \
+     && (COPY(emitter->buffer,string),                                          \
+         emitter->column ++,                                                    \
+         1))
+
+/*
+ * Copy a line break character from a string into buffer.
+ */
+
+#define WRITE_BREAK(emitter,string)                                             \
+    (FLUSH(emitter)                                                             \
+     && (CHECK(string,'\n') ?                                                   \
+         (PUT_BREAK(emitter),                                                   \
+          string.pointer ++,                                                    \
+          1) :                                                                  \
+         (COPY(emitter->buffer,string),                                         \
+          emitter->column = 0,                                                  \
+          emitter->line ++,                                                     \
+          1)))
+
+/*
+ * API functions.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_emit(yaml_emitter_t *emitter, yaml_event_t *event);
+
+/*
+ * Utility functions.
+ */
+
+static int
+yaml_emitter_set_emitter_error(yaml_emitter_t *emitter, const char *problem);
+
+static int
+yaml_emitter_need_more_events(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_append_tag_directive(yaml_emitter_t *emitter,
+        yaml_tag_directive_t value, int allow_duplicates);
+
+static int
+yaml_emitter_increase_indent(yaml_emitter_t *emitter,
+        int flow, int indentless);
+
+/*
+ * State functions.
+ */
+
+static int
+yaml_emitter_state_machine(yaml_emitter_t *emitter, yaml_event_t *event);
+
+static int
+yaml_emitter_emit_stream_start(yaml_emitter_t *emitter,
+        yaml_event_t *event);
+
+static int
+yaml_emitter_emit_document_start(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first);
+
+static int
+yaml_emitter_emit_document_content(yaml_emitter_t *emitter,
+        yaml_event_t *event);
+
+static int
+yaml_emitter_emit_document_end(yaml_emitter_t *emitter,
+        yaml_event_t *event);
+
+static int
+yaml_emitter_emit_flow_sequence_item(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first);
+
+static int
+yaml_emitter_emit_flow_mapping_key(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first);
+
+static int
+yaml_emitter_emit_flow_mapping_value(yaml_emitter_t *emitter,
+        yaml_event_t *event, int simple);
+
+static int
+yaml_emitter_emit_block_sequence_item(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first);
+
+static int
+yaml_emitter_emit_block_mapping_key(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first);
+
+static int
+yaml_emitter_emit_block_mapping_value(yaml_emitter_t *emitter,
+        yaml_event_t *event, int simple);
+
+static int
+yaml_emitter_emit_node(yaml_emitter_t *emitter, yaml_event_t *event,
+        int root, int sequence, int mapping, int simple_key);
+
+static int
+yaml_emitter_emit_alias(yaml_emitter_t *emitter, yaml_event_t *event);
+
+static int
+yaml_emitter_emit_scalar(yaml_emitter_t *emitter, yaml_event_t *event);
+
+static int
+yaml_emitter_emit_sequence_start(yaml_emitter_t *emitter, yaml_event_t *event);
+
+static int
+yaml_emitter_emit_mapping_start(yaml_emitter_t *emitter, yaml_event_t *event);
+
+/*
+ * Checkers.
+ */
+
+static int
+yaml_emitter_check_empty_document(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_check_empty_sequence(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_check_empty_mapping(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_check_simple_key(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_select_scalar_style(yaml_emitter_t *emitter, yaml_event_t *event);
+
+/*
+ * Processors.
+ */
+
+static int
+yaml_emitter_process_anchor(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_process_tag(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_process_scalar(yaml_emitter_t *emitter);
+
+/*
+ * Analyzers.
+ */
+
+static int
+yaml_emitter_analyze_version_directive(yaml_emitter_t *emitter,
+        yaml_version_directive_t version_directive);
+
+static int
+yaml_emitter_analyze_tag_directive(yaml_emitter_t *emitter,
+        yaml_tag_directive_t tag_directive);
+
+static int
+yaml_emitter_analyze_anchor(yaml_emitter_t *emitter,
+        yaml_char_t *anchor, int alias);
+
+static int
+yaml_emitter_analyze_tag(yaml_emitter_t *emitter,
+        yaml_char_t *tag);
+
+static int
+yaml_emitter_analyze_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length);
+
+static int
+yaml_emitter_analyze_event(yaml_emitter_t *emitter,
+        yaml_event_t *event);
+
+/*
+ * Writers.
+ */
+
+static int
+yaml_emitter_write_bom(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_write_indent(yaml_emitter_t *emitter);
+
+static int
+yaml_emitter_write_indicator(yaml_emitter_t *emitter,
+        const char *indicator, int need_whitespace,
+        int is_whitespace, int is_indention);
+
+static int
+yaml_emitter_write_anchor(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length);
+
+static int
+yaml_emitter_write_tag_handle(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length);
+
+static int
+yaml_emitter_write_tag_content(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int need_whitespace);
+
+static int
+yaml_emitter_write_plain_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks);
+
+static int
+yaml_emitter_write_single_quoted_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks);
+
+static int
+yaml_emitter_write_double_quoted_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks);
+
+static int
+yaml_emitter_write_block_scalar_hints(yaml_emitter_t *emitter,
+        yaml_string_t string);
+
+static int
+yaml_emitter_write_literal_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length);
+
+static int
+yaml_emitter_write_folded_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length);
+
+/*
+ * Set an emitter error and return 0.
+ */
+
+static int
+yaml_emitter_set_emitter_error(yaml_emitter_t *emitter, const char *problem)
+{
+    emitter->error = YAML_EMITTER_ERROR;
+    emitter->problem = problem;
+
+    return 0;
+}
+
+/*
+ * Emit an event.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_emit(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    if (!ENQUEUE(emitter, emitter->events, *event)) {
+        yaml_event_delete(event);
+        return 0;
+    }
+
+    while (!yaml_emitter_need_more_events(emitter)) {
+        if (!yaml_emitter_analyze_event(emitter, emitter->events.head))
+            return 0;
+        if (!yaml_emitter_state_machine(emitter, emitter->events.head))
+            return 0;
+        yaml_event_delete(&DEQUEUE(emitter, emitter->events));
+    }
+
+    return 1;
+}
+
+/*
+ * Check if we need to accumulate more events before emitting.
+ *
+ * We accumulate extra
+ *  - 1 event for DOCUMENT-START
+ *  - 2 events for SEQUENCE-START
+ *  - 3 events for MAPPING-START
+ */
+
+static int
+yaml_emitter_need_more_events(yaml_emitter_t *emitter)
+{
+    int level = 0;
+    int accumulate = 0;
+    yaml_event_t *event;
+
+    if (QUEUE_EMPTY(emitter, emitter->events))
+        return 1;
+
+    switch (emitter->events.head->type) {
+        case YAML_DOCUMENT_START_EVENT:
+            accumulate = 1;
+            break;
+        case YAML_SEQUENCE_START_EVENT:
+            accumulate = 2;
+            break;
+        case YAML_MAPPING_START_EVENT:
+            accumulate = 3;
+            break;
+        default:
+            return 0;
+    }
+
+    if (emitter->events.tail - emitter->events.head > accumulate)
+        return 0;
+
+    for (event = emitter->events.head; event != emitter->events.tail; event ++) {
+        switch (event->type) {
+            case YAML_STREAM_START_EVENT:
+            case YAML_DOCUMENT_START_EVENT:
+            case YAML_SEQUENCE_START_EVENT:
+            case YAML_MAPPING_START_EVENT:
+                level += 1;
+                break;
+            case YAML_STREAM_END_EVENT:
+            case YAML_DOCUMENT_END_EVENT:
+            case YAML_SEQUENCE_END_EVENT:
+            case YAML_MAPPING_END_EVENT:
+                level -= 1;
+                break;
+            default:
+                break;
+        }
+        if (!level)
+            return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Append a directive to the directives stack.
+ */
+
+static int
+yaml_emitter_append_tag_directive(yaml_emitter_t *emitter,
+        yaml_tag_directive_t value, int allow_duplicates)
+{
+    yaml_tag_directive_t *tag_directive;
+    yaml_tag_directive_t copy = { NULL, NULL };
+
+    for (tag_directive = emitter->tag_directives.start;
+            tag_directive != emitter->tag_directives.top; tag_directive ++) {
+        if (strcmp((char *)value.handle, (char *)tag_directive->handle) == 0) {
+            if (allow_duplicates)
+                return 1;
+            return yaml_emitter_set_emitter_error(emitter,
+                    "duplicate %TAG directive");
+        }
+    }
+
+    copy.handle = yaml_strdup(value.handle);
+    copy.prefix = yaml_strdup(value.prefix);
+    if (!copy.handle || !copy.prefix) {
+        emitter->error = YAML_MEMORY_ERROR;
+        goto error;
+    }
+
+    if (!PUSH(emitter, emitter->tag_directives, copy))
+        goto error;
+
+    return 1;
+
+error:
+    yaml_free(copy.handle);
+    yaml_free(copy.prefix);
+    return 0;
+}
+
+/*
+ * Increase the indentation level.
+ */
+
+static int
+yaml_emitter_increase_indent(yaml_emitter_t *emitter,
+        int flow, int indentless)
+{
+    if (!PUSH(emitter, emitter->indents, emitter->indent))
+        return 0;
+
+    if (emitter->indent < 0) {
+        emitter->indent = flow ? emitter->best_indent : 0;
+    }
+    else if (!indentless) {
+        emitter->indent += emitter->best_indent;
+    }
+
+    return 1;
+}
+
+/*
+ * State dispatcher.
+ */
+
+static int
+yaml_emitter_state_machine(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    switch (emitter->state)
+    {
+        case YAML_EMIT_STREAM_START_STATE:
+            return yaml_emitter_emit_stream_start(emitter, event);
+
+        case YAML_EMIT_FIRST_DOCUMENT_START_STATE:
+            return yaml_emitter_emit_document_start(emitter, event, 1);
+
+        case YAML_EMIT_DOCUMENT_START_STATE:
+            return yaml_emitter_emit_document_start(emitter, event, 0);
+
+        case YAML_EMIT_DOCUMENT_CONTENT_STATE:
+            return yaml_emitter_emit_document_content(emitter, event);
+
+        case YAML_EMIT_DOCUMENT_END_STATE:
+            return yaml_emitter_emit_document_end(emitter, event);
+
+        case YAML_EMIT_FLOW_SEQUENCE_FIRST_ITEM_STATE:
+            return yaml_emitter_emit_flow_sequence_item(emitter, event, 1);
+
+        case YAML_EMIT_FLOW_SEQUENCE_ITEM_STATE:
+            return yaml_emitter_emit_flow_sequence_item(emitter, event, 0);
+
+        case YAML_EMIT_FLOW_MAPPING_FIRST_KEY_STATE:
+            return yaml_emitter_emit_flow_mapping_key(emitter, event, 1);
+
+        case YAML_EMIT_FLOW_MAPPING_KEY_STATE:
+            return yaml_emitter_emit_flow_mapping_key(emitter, event, 0);
+
+        case YAML_EMIT_FLOW_MAPPING_SIMPLE_VALUE_STATE:
+            return yaml_emitter_emit_flow_mapping_value(emitter, event, 1);
+
+        case YAML_EMIT_FLOW_MAPPING_VALUE_STATE:
+            return yaml_emitter_emit_flow_mapping_value(emitter, event, 0);
+
+        case YAML_EMIT_BLOCK_SEQUENCE_FIRST_ITEM_STATE:
+            return yaml_emitter_emit_block_sequence_item(emitter, event, 1);
+
+        case YAML_EMIT_BLOCK_SEQUENCE_ITEM_STATE:
+            return yaml_emitter_emit_block_sequence_item(emitter, event, 0);
+
+        case YAML_EMIT_BLOCK_MAPPING_FIRST_KEY_STATE:
+            return yaml_emitter_emit_block_mapping_key(emitter, event, 1);
+
+        case YAML_EMIT_BLOCK_MAPPING_KEY_STATE:
+            return yaml_emitter_emit_block_mapping_key(emitter, event, 0);
+
+        case YAML_EMIT_BLOCK_MAPPING_SIMPLE_VALUE_STATE:
+            return yaml_emitter_emit_block_mapping_value(emitter, event, 1);
+
+        case YAML_EMIT_BLOCK_MAPPING_VALUE_STATE:
+            return yaml_emitter_emit_block_mapping_value(emitter, event, 0);
+
+        case YAML_EMIT_END_STATE:
+            return yaml_emitter_set_emitter_error(emitter,
+                    "expected nothing after STREAM-END");
+
+        default:
+            assert(1);      /* Invalid state. */
+    }
+
+    return 0;
+}
+
+/*
+ * Expect STREAM-START.
+ */
+
+static int
+yaml_emitter_emit_stream_start(yaml_emitter_t *emitter,
+        yaml_event_t *event)
+{
+    emitter->open_ended = 0;
+    if (event->type == YAML_STREAM_START_EVENT)
+    {
+        if (!emitter->encoding) {
+            emitter->encoding = event->data.stream_start.encoding;
+        }
+
+        if (!emitter->encoding) {
+            emitter->encoding = YAML_UTF8_ENCODING;
+        }
+
+        if (emitter->best_indent < 2 || emitter->best_indent > 9) {
+            emitter->best_indent  = 2;
+        }
+
+        if (emitter->best_width >= 0
+                && emitter->best_width <= emitter->best_indent*2) {
+            emitter->best_width = 80;
+        }
+
+        if (emitter->best_width < 0) {
+            emitter->best_width = INT_MAX;
+        }
+
+        if (!emitter->line_break) {
+            emitter->line_break = YAML_LN_BREAK;
+        }
+
+        emitter->indent = -1;
+
+        emitter->line = 0;
+        emitter->column = 0;
+        emitter->whitespace = 1;
+        emitter->indention = 1;
+
+        if (emitter->encoding != YAML_UTF8_ENCODING) {
+            if (!yaml_emitter_write_bom(emitter))
+                return 0;
+        }
+
+        emitter->state = YAML_EMIT_FIRST_DOCUMENT_START_STATE;
+
+        return 1;
+    }
+
+    return yaml_emitter_set_emitter_error(emitter,
+            "expected STREAM-START");
+}
+
+/*
+ * Expect DOCUMENT-START or STREAM-END.
+ */
+
+static int
+yaml_emitter_emit_document_start(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first)
+{
+    if (event->type == YAML_DOCUMENT_START_EVENT)
+    {
+        yaml_tag_directive_t default_tag_directives[] = {
+            {(yaml_char_t *)"!", (yaml_char_t *)"!"},
+            {(yaml_char_t *)"!!", (yaml_char_t *)"tag:yaml.org,2002:"},
+            {NULL, NULL}
+        };
+        yaml_tag_directive_t *tag_directive;
+        int implicit;
+
+        if (event->data.document_start.version_directive) {
+            if (!yaml_emitter_analyze_version_directive(emitter,
+                        *event->data.document_start.version_directive))
+                return 0;
+        }
+
+        for (tag_directive = event->data.document_start.tag_directives.start;
+                tag_directive != event->data.document_start.tag_directives.end;
+                tag_directive ++) {
+            if (!yaml_emitter_analyze_tag_directive(emitter, *tag_directive))
+                return 0;
+            if (!yaml_emitter_append_tag_directive(emitter, *tag_directive, 0))
+                return 0;
+        }
+
+        for (tag_directive = default_tag_directives;
+                tag_directive->handle; tag_directive ++) {
+            if (!yaml_emitter_append_tag_directive(emitter, *tag_directive, 1))
+                return 0;
+        }
+
+        implicit = event->data.document_start.implicit;
+        if (!first || emitter->canonical) {
+            implicit = 0;
+        }
+
+        if ((event->data.document_start.version_directive ||
+                    (event->data.document_start.tag_directives.start
+                     != event->data.document_start.tag_directives.end)) &&
+                emitter->open_ended)
+        {
+            if (!yaml_emitter_write_indicator(emitter, "...", 1, 0, 0))
+                return 0;
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+        emitter->open_ended = 0;
+
+        if (event->data.document_start.version_directive) {
+            implicit = 0;
+            if (!yaml_emitter_write_indicator(emitter, "%YAML", 1, 0, 0))
+                return 0;
+            if (event->data.document_start.version_directive->minor == 1) {
+                if (!yaml_emitter_write_indicator(emitter, "1.1", 1, 0, 0))
+                    return 0;
+            }
+            else {
+                if (!yaml_emitter_write_indicator(emitter, "1.2", 1, 0, 0))
+                    return 0;
+            }
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+
+        if (event->data.document_start.tag_directives.start
+                != event->data.document_start.tag_directives.end) {
+            implicit = 0;
+            for (tag_directive = event->data.document_start.tag_directives.start;
+                    tag_directive != event->data.document_start.tag_directives.end;
+                    tag_directive ++) {
+                if (!yaml_emitter_write_indicator(emitter, "%TAG", 1, 0, 0))
+                    return 0;
+                if (!yaml_emitter_write_tag_handle(emitter, tag_directive->handle,
+                            strlen((char *)tag_directive->handle)))
+                    return 0;
+                if (!yaml_emitter_write_tag_content(emitter, tag_directive->prefix,
+                            strlen((char *)tag_directive->prefix), 1))
+                    return 0;
+                if (!yaml_emitter_write_indent(emitter))
+                    return 0;
+            }
+        }
+
+        if (yaml_emitter_check_empty_document(emitter)) {
+            implicit = 0;
+        }
+
+        if (!implicit) {
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+            if (!yaml_emitter_write_indicator(emitter, "---", 1, 0, 0))
+                return 0;
+            if (emitter->canonical) {
+                if (!yaml_emitter_write_indent(emitter))
+                    return 0;
+            }
+        }
+
+        emitter->state = YAML_EMIT_DOCUMENT_CONTENT_STATE;
+
+        emitter->open_ended = 0;
+        return 1;
+    }
+
+    else if (event->type == YAML_STREAM_END_EVENT)
+    {
+
+        /**
+         * This can happen if a block scalar with trailing empty lines
+         * is at the end of the stream
+         */
+        if (emitter->open_ended == 2)
+        {
+            if (!yaml_emitter_write_indicator(emitter, "...", 1, 0, 0))
+                return 0;
+            emitter->open_ended = 0;
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+        if (!yaml_emitter_flush(emitter))
+            return 0;
+
+        emitter->state = YAML_EMIT_END_STATE;
+
+        return 1;
+    }
+
+    return yaml_emitter_set_emitter_error(emitter,
+            "expected DOCUMENT-START or STREAM-END");
+}
+
+/*
+ * Expect the root node.
+ */
+
+static int
+yaml_emitter_emit_document_content(yaml_emitter_t *emitter,
+        yaml_event_t *event)
+{
+    if (!PUSH(emitter, emitter->states, YAML_EMIT_DOCUMENT_END_STATE))
+        return 0;
+
+    return yaml_emitter_emit_node(emitter, event, 1, 0, 0, 0);
+}
+
+/*
+ * Expect DOCUMENT-END.
+ */
+
+static int
+yaml_emitter_emit_document_end(yaml_emitter_t *emitter,
+        yaml_event_t *event)
+{
+    if (event->type == YAML_DOCUMENT_END_EVENT)
+    {
+        if (!yaml_emitter_write_indent(emitter))
+            return 0;
+        if (!event->data.document_end.implicit) {
+            if (!yaml_emitter_write_indicator(emitter, "...", 1, 0, 0))
+                return 0;
+            emitter->open_ended = 0;
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+        else if (!emitter->open_ended)
+            emitter->open_ended = 1;
+        if (!yaml_emitter_flush(emitter))
+            return 0;
+
+        emitter->state = YAML_EMIT_DOCUMENT_START_STATE;
+
+        while (!STACK_EMPTY(emitter, emitter->tag_directives)) {
+            yaml_tag_directive_t tag_directive = POP(emitter,
+                    emitter->tag_directives);
+            yaml_free(tag_directive.handle);
+            yaml_free(tag_directive.prefix);
+        }
+
+        return 1;
+    }
+
+    return yaml_emitter_set_emitter_error(emitter,
+            "expected DOCUMENT-END");
+}
+
+/*
+ *
+ * Expect a flow item node.
+ */
+
+static int
+yaml_emitter_emit_flow_sequence_item(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first)
+{
+    if (first)
+    {
+        if (!yaml_emitter_write_indicator(emitter, "[", 1, 1, 0))
+            return 0;
+        if (!yaml_emitter_increase_indent(emitter, 1, 0))
+            return 0;
+        emitter->flow_level ++;
+    }
+
+    if (event->type == YAML_SEQUENCE_END_EVENT)
+    {
+        emitter->flow_level --;
+        emitter->indent = POP(emitter, emitter->indents);
+        if (emitter->canonical && !first) {
+            if (!yaml_emitter_write_indicator(emitter, ",", 0, 0, 0))
+                return 0;
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+        if (!yaml_emitter_write_indicator(emitter, "]", 0, 0, 0))
+            return 0;
+        emitter->state = POP(emitter, emitter->states);
+
+        return 1;
+    }
+
+    if (!first) {
+        if (!yaml_emitter_write_indicator(emitter, ",", 0, 0, 0))
+            return 0;
+    }
+
+    if (emitter->canonical || emitter->column > emitter->best_width) {
+        if (!yaml_emitter_write_indent(emitter))
+            return 0;
+    }
+    if (!PUSH(emitter, emitter->states, YAML_EMIT_FLOW_SEQUENCE_ITEM_STATE))
+        return 0;
+
+    return yaml_emitter_emit_node(emitter, event, 0, 1, 0, 0);
+}
+
+/*
+ * Expect a flow key node.
+ */
+
+static int
+yaml_emitter_emit_flow_mapping_key(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first)
+{
+    if (first)
+    {
+        if (!yaml_emitter_write_indicator(emitter, "{", 1, 1, 0))
+            return 0;
+        if (!yaml_emitter_increase_indent(emitter, 1, 0))
+            return 0;
+        emitter->flow_level ++;
+    }
+
+    if (event->type == YAML_MAPPING_END_EVENT)
+    {
+        emitter->flow_level --;
+        emitter->indent = POP(emitter, emitter->indents);
+        if (emitter->canonical && !first) {
+            if (!yaml_emitter_write_indicator(emitter, ",", 0, 0, 0))
+                return 0;
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+        if (!yaml_emitter_write_indicator(emitter, "}", 0, 0, 0))
+            return 0;
+        emitter->state = POP(emitter, emitter->states);
+
+        return 1;
+    }
+
+    if (!first) {
+        if (!yaml_emitter_write_indicator(emitter, ",", 0, 0, 0))
+            return 0;
+    }
+    if (emitter->canonical || emitter->column > emitter->best_width) {
+        if (!yaml_emitter_write_indent(emitter))
+            return 0;
+    }
+
+    if (!emitter->canonical && yaml_emitter_check_simple_key(emitter))
+    {
+        if (!PUSH(emitter, emitter->states,
+                    YAML_EMIT_FLOW_MAPPING_SIMPLE_VALUE_STATE))
+            return 0;
+
+        return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 1);
+    }
+    else
+    {
+        if (!yaml_emitter_write_indicator(emitter, "?", 1, 0, 0))
+            return 0;
+        if (!PUSH(emitter, emitter->states,
+                    YAML_EMIT_FLOW_MAPPING_VALUE_STATE))
+            return 0;
+
+        return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 0);
+    }
+}
+
+/*
+ * Expect a flow value node.
+ */
+
+static int
+yaml_emitter_emit_flow_mapping_value(yaml_emitter_t *emitter,
+        yaml_event_t *event, int simple)
+{
+    if (simple) {
+        if (!yaml_emitter_write_indicator(emitter, ":", 0, 0, 0))
+            return 0;
+    }
+    else {
+        if (emitter->canonical || emitter->column > emitter->best_width) {
+            if (!yaml_emitter_write_indent(emitter))
+                return 0;
+        }
+        if (!yaml_emitter_write_indicator(emitter, ":", 1, 0, 0))
+            return 0;
+    }
+    if (!PUSH(emitter, emitter->states, YAML_EMIT_FLOW_MAPPING_KEY_STATE))
+        return 0;
+    return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 0);
+}
+
+/*
+ * Expect a block item node.
+ */
+
+static int
+yaml_emitter_emit_block_sequence_item(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first)
+{
+    if (first)
+    {
+        if (!yaml_emitter_increase_indent(emitter, 0,
+                    (emitter->mapping_context && !emitter->indention)))
+            return 0;
+    }
+
+    if (event->type == YAML_SEQUENCE_END_EVENT)
+    {
+        emitter->indent = POP(emitter, emitter->indents);
+        emitter->state = POP(emitter, emitter->states);
+
+        return 1;
+    }
+
+    if (!yaml_emitter_write_indent(emitter))
+        return 0;
+    if (!yaml_emitter_write_indicator(emitter, "-", 1, 0, 1))
+        return 0;
+    if (!PUSH(emitter, emitter->states,
+                YAML_EMIT_BLOCK_SEQUENCE_ITEM_STATE))
+        return 0;
+
+    return yaml_emitter_emit_node(emitter, event, 0, 1, 0, 0);
+}
+
+/*
+ * Expect a block key node.
+ */
+
+static int
+yaml_emitter_emit_block_mapping_key(yaml_emitter_t *emitter,
+        yaml_event_t *event, int first)
+{
+    if (first)
+    {
+        if (!yaml_emitter_increase_indent(emitter, 0, 0))
+            return 0;
+    }
+
+    if (event->type == YAML_MAPPING_END_EVENT)
+    {
+        emitter->indent = POP(emitter, emitter->indents);
+        emitter->state = POP(emitter, emitter->states);
+
+        return 1;
+    }
+
+    if (!yaml_emitter_write_indent(emitter))
+        return 0;
+
+    if (yaml_emitter_check_simple_key(emitter))
+    {
+        if (!PUSH(emitter, emitter->states,
+                    YAML_EMIT_BLOCK_MAPPING_SIMPLE_VALUE_STATE))
+            return 0;
+
+        return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 1);
+    }
+    else
+    {
+        if (!yaml_emitter_write_indicator(emitter, "?", 1, 0, 1))
+            return 0;
+        if (!PUSH(emitter, emitter->states,
+                    YAML_EMIT_BLOCK_MAPPING_VALUE_STATE))
+            return 0;
+
+        return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 0);
+    }
+}
+
+/*
+ * Expect a block value node.
+ */
+
+static int
+yaml_emitter_emit_block_mapping_value(yaml_emitter_t *emitter,
+        yaml_event_t *event, int simple)
+{
+    if (simple) {
+        if (!yaml_emitter_write_indicator(emitter, ":", 0, 0, 0))
+            return 0;
+    }
+    else {
+        if (!yaml_emitter_write_indent(emitter))
+            return 0;
+        if (!yaml_emitter_write_indicator(emitter, ":", 1, 0, 1))
+            return 0;
+    }
+    if (!PUSH(emitter, emitter->states,
+                YAML_EMIT_BLOCK_MAPPING_KEY_STATE))
+        return 0;
+
+    return yaml_emitter_emit_node(emitter, event, 0, 0, 1, 0);
+}
+
+/*
+ * Expect a node.
+ */
+
+static int
+yaml_emitter_emit_node(yaml_emitter_t *emitter, yaml_event_t *event,
+        int root, int sequence, int mapping, int simple_key)
+{
+    emitter->root_context = root;
+    emitter->sequence_context = sequence;
+    emitter->mapping_context = mapping;
+    emitter->simple_key_context = simple_key;
+
+    switch (event->type)
+    {
+        case YAML_ALIAS_EVENT:
+            return yaml_emitter_emit_alias(emitter, event);
+
+        case YAML_SCALAR_EVENT:
+            return yaml_emitter_emit_scalar(emitter, event);
+
+        case YAML_SEQUENCE_START_EVENT:
+            return yaml_emitter_emit_sequence_start(emitter, event);
+
+        case YAML_MAPPING_START_EVENT:
+            return yaml_emitter_emit_mapping_start(emitter, event);
+
+        default:
+            return yaml_emitter_set_emitter_error(emitter,
+                    "expected SCALAR, SEQUENCE-START, MAPPING-START, or ALIAS");
+    }
+
+    return 0;
+}
+
+/*
+ * Expect ALIAS.
+ */
+
+static int
+yaml_emitter_emit_alias(yaml_emitter_t *emitter, SHIM(yaml_event_t *event))
+{
+    if (!yaml_emitter_process_anchor(emitter))
+        return 0;
+    if (emitter->simple_key_context)
+        if (!PUT(emitter, ' ')) return 0;
+    emitter->state = POP(emitter, emitter->states);
+
+    return 1;
+}
+
+/*
+ * Expect SCALAR.
+ */
+
+static int
+yaml_emitter_emit_scalar(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    if (!yaml_emitter_select_scalar_style(emitter, event))
+        return 0;
+    if (!yaml_emitter_process_anchor(emitter))
+        return 0;
+    if (!yaml_emitter_process_tag(emitter))
+        return 0;
+    if (!yaml_emitter_increase_indent(emitter, 1, 0))
+        return 0;
+    if (!yaml_emitter_process_scalar(emitter))
+        return 0;
+    emitter->indent = POP(emitter, emitter->indents);
+    emitter->state = POP(emitter, emitter->states);
+
+    return 1;
+}
+
+/*
+ * Expect SEQUENCE-START.
+ */
+
+static int
+yaml_emitter_emit_sequence_start(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    if (!yaml_emitter_process_anchor(emitter))
+        return 0;
+    if (!yaml_emitter_process_tag(emitter))
+        return 0;
+
+    if (emitter->flow_level || emitter->canonical
+            || event->data.sequence_start.style == YAML_FLOW_SEQUENCE_STYLE
+            || yaml_emitter_check_empty_sequence(emitter)) {
+        emitter->state = YAML_EMIT_FLOW_SEQUENCE_FIRST_ITEM_STATE;
+    }
+    else {
+        emitter->state = YAML_EMIT_BLOCK_SEQUENCE_FIRST_ITEM_STATE;
+    }
+
+    return 1;
+}
+
+/*
+ * Expect MAPPING-START.
+ */
+
+static int
+yaml_emitter_emit_mapping_start(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    if (!yaml_emitter_process_anchor(emitter))
+        return 0;
+    if (!yaml_emitter_process_tag(emitter))
+        return 0;
+
+    if (emitter->flow_level || emitter->canonical
+            || event->data.mapping_start.style == YAML_FLOW_MAPPING_STYLE
+            || yaml_emitter_check_empty_mapping(emitter)) {
+        emitter->state = YAML_EMIT_FLOW_MAPPING_FIRST_KEY_STATE;
+    }
+    else {
+        emitter->state = YAML_EMIT_BLOCK_MAPPING_FIRST_KEY_STATE;
+    }
+
+    return 1;
+}
+
+/*
+ * Check if the document content is an empty scalar.
+ */
+
+static int
+yaml_emitter_check_empty_document(SHIM(yaml_emitter_t *emitter))
+{
+    return 0;
+}
+
+/*
+ * Check if the next events represent an empty sequence.
+ */
+
+static int
+yaml_emitter_check_empty_sequence(yaml_emitter_t *emitter)
+{
+    if (emitter->events.tail - emitter->events.head < 2)
+        return 0;
+
+    return (emitter->events.head[0].type == YAML_SEQUENCE_START_EVENT
+            && emitter->events.head[1].type == YAML_SEQUENCE_END_EVENT);
+}
+
+/*
+ * Check if the next events represent an empty mapping.
+ */
+
+static int
+yaml_emitter_check_empty_mapping(yaml_emitter_t *emitter)
+{
+    if (emitter->events.tail - emitter->events.head < 2)
+        return 0;
+
+    return (emitter->events.head[0].type == YAML_MAPPING_START_EVENT
+            && emitter->events.head[1].type == YAML_MAPPING_END_EVENT);
+}
+
+/*
+ * Check if the next node can be expressed as a simple key.
+ */
+
+static int
+yaml_emitter_check_simple_key(yaml_emitter_t *emitter)
+{
+    yaml_event_t *event = emitter->events.head;
+    size_t length = 0;
+
+    switch (event->type)
+    {
+        case YAML_ALIAS_EVENT:
+            length += emitter->anchor_data.anchor_length;
+            break;
+
+        case YAML_SCALAR_EVENT:
+            if (emitter->scalar_data.multiline)
+                return 0;
+            length += emitter->anchor_data.anchor_length
+                + emitter->tag_data.handle_length
+                + emitter->tag_data.suffix_length
+                + emitter->scalar_data.length;
+            break;
+
+        case YAML_SEQUENCE_START_EVENT:
+            if (!yaml_emitter_check_empty_sequence(emitter))
+                return 0;
+            length += emitter->anchor_data.anchor_length
+                + emitter->tag_data.handle_length
+                + emitter->tag_data.suffix_length;
+            break;
+
+        case YAML_MAPPING_START_EVENT:
+            if (!yaml_emitter_check_empty_mapping(emitter))
+                return 0;
+            length += emitter->anchor_data.anchor_length
+                + emitter->tag_data.handle_length
+                + emitter->tag_data.suffix_length;
+            break;
+
+        default:
+            return 0;
+    }
+
+    if (length > 128)
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Determine an acceptable scalar style.
+ */
+
+static int
+yaml_emitter_select_scalar_style(yaml_emitter_t *emitter, yaml_event_t *event)
+{
+    yaml_scalar_style_t style = event->data.scalar.style;
+    int no_tag = (!emitter->tag_data.handle && !emitter->tag_data.suffix);
+
+    if (no_tag && !event->data.scalar.plain_implicit
+            && !event->data.scalar.quoted_implicit) {
+        return yaml_emitter_set_emitter_error(emitter,
+                "neither tag nor implicit flags are specified");
+    }
+
+    if (style == YAML_ANY_SCALAR_STYLE)
+        style = YAML_PLAIN_SCALAR_STYLE;
+
+    if (emitter->canonical)
+        style = YAML_DOUBLE_QUOTED_SCALAR_STYLE;
+
+    if (emitter->simple_key_context && emitter->scalar_data.multiline)
+        style = YAML_DOUBLE_QUOTED_SCALAR_STYLE;
+
+    if (style == YAML_PLAIN_SCALAR_STYLE)
+    {
+        if ((emitter->flow_level && !emitter->scalar_data.flow_plain_allowed)
+                || (!emitter->flow_level && !emitter->scalar_data.block_plain_allowed))
+            style = YAML_SINGLE_QUOTED_SCALAR_STYLE;
+        if (!emitter->scalar_data.length
+                && (emitter->flow_level || emitter->simple_key_context))
+            style = YAML_SINGLE_QUOTED_SCALAR_STYLE;
+        if (no_tag && !event->data.scalar.plain_implicit)
+            style = YAML_SINGLE_QUOTED_SCALAR_STYLE;
+    }
+
+    if (style == YAML_SINGLE_QUOTED_SCALAR_STYLE)
+    {
+        if (!emitter->scalar_data.single_quoted_allowed)
+            style = YAML_DOUBLE_QUOTED_SCALAR_STYLE;
+    }
+
+    if (style == YAML_LITERAL_SCALAR_STYLE || style == YAML_FOLDED_SCALAR_STYLE)
+    {
+        if (!emitter->scalar_data.block_allowed
+                || emitter->flow_level || emitter->simple_key_context)
+            style = YAML_DOUBLE_QUOTED_SCALAR_STYLE;
+    }
+
+    if (no_tag && !event->data.scalar.quoted_implicit
+            && style != YAML_PLAIN_SCALAR_STYLE)
+    {
+        emitter->tag_data.handle = (yaml_char_t *)"!";
+        emitter->tag_data.handle_length = 1;
+    }
+
+    emitter->scalar_data.style = style;
+
+    return 1;
+}
+
+/*
+ * Write an anchor.
+ */
+
+static int
+yaml_emitter_process_anchor(yaml_emitter_t *emitter)
+{
+    if (!emitter->anchor_data.anchor)
+        return 1;
+
+    if (!yaml_emitter_write_indicator(emitter,
+                (emitter->anchor_data.alias ? "*" : "&"), 1, 0, 0))
+        return 0;
+
+    return yaml_emitter_write_anchor(emitter,
+            emitter->anchor_data.anchor, emitter->anchor_data.anchor_length);
+}
+
+/*
+ * Write a tag.
+ */
+
+static int
+yaml_emitter_process_tag(yaml_emitter_t *emitter)
+{
+    if (!emitter->tag_data.handle && !emitter->tag_data.suffix)
+        return 1;
+
+    if (emitter->tag_data.handle)
+    {
+        if (!yaml_emitter_write_tag_handle(emitter, emitter->tag_data.handle,
+                    emitter->tag_data.handle_length))
+            return 0;
+        if (emitter->tag_data.suffix) {
+            if (!yaml_emitter_write_tag_content(emitter, emitter->tag_data.suffix,
+                        emitter->tag_data.suffix_length, 0))
+                return 0;
+        }
+    }
+    else
+    {
+        if (!yaml_emitter_write_indicator(emitter, "!<", 1, 0, 0))
+            return 0;
+        if (!yaml_emitter_write_tag_content(emitter, emitter->tag_data.suffix,
+                    emitter->tag_data.suffix_length, 0))
+            return 0;
+        if (!yaml_emitter_write_indicator(emitter, ">", 0, 0, 0))
+            return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Write a scalar.
+ */
+
+static int
+yaml_emitter_process_scalar(yaml_emitter_t *emitter)
+{
+    switch (emitter->scalar_data.style)
+    {
+        case YAML_PLAIN_SCALAR_STYLE:
+            return yaml_emitter_write_plain_scalar(emitter,
+                    emitter->scalar_data.value, emitter->scalar_data.length,
+                    !emitter->simple_key_context);
+
+        case YAML_SINGLE_QUOTED_SCALAR_STYLE:
+            return yaml_emitter_write_single_quoted_scalar(emitter,
+                    emitter->scalar_data.value, emitter->scalar_data.length,
+                    !emitter->simple_key_context);
+
+        case YAML_DOUBLE_QUOTED_SCALAR_STYLE:
+            return yaml_emitter_write_double_quoted_scalar(emitter,
+                    emitter->scalar_data.value, emitter->scalar_data.length,
+                    !emitter->simple_key_context);
+
+        case YAML_LITERAL_SCALAR_STYLE:
+            return yaml_emitter_write_literal_scalar(emitter,
+                    emitter->scalar_data.value, emitter->scalar_data.length);
+
+        case YAML_FOLDED_SCALAR_STYLE:
+            return yaml_emitter_write_folded_scalar(emitter,
+                    emitter->scalar_data.value, emitter->scalar_data.length);
+
+        default:
+            assert(1);      /* Impossible. */
+    }
+
+    return 0;
+}
+
+/*
+ * Check if a %YAML directive is valid.
+ */
+
+static int
+yaml_emitter_analyze_version_directive(yaml_emitter_t *emitter,
+        yaml_version_directive_t version_directive)
+{
+    if (version_directive.major != 1 || (
+        version_directive.minor != 1
+        && version_directive.minor != 2
+        )) {
+        return yaml_emitter_set_emitter_error(emitter,
+                "incompatible %YAML directive");
+    }
+
+    return 1;
+}
+
+/*
+ * Check if a %TAG directive is valid.
+ */
+
+static int
+yaml_emitter_analyze_tag_directive(yaml_emitter_t *emitter,
+        yaml_tag_directive_t tag_directive)
+{
+    yaml_string_t handle;
+    yaml_string_t prefix;
+    size_t handle_length;
+    size_t prefix_length;
+
+    handle_length = strlen((char *)tag_directive.handle);
+    prefix_length = strlen((char *)tag_directive.prefix);
+    STRING_ASSIGN(handle, tag_directive.handle, handle_length);
+    STRING_ASSIGN(prefix, tag_directive.prefix, prefix_length);
+
+    if (handle.start == handle.end) {
+        return yaml_emitter_set_emitter_error(emitter,
+                "tag handle must not be empty");
+    }
+
+    if (handle.start[0] != '!') {
+        return yaml_emitter_set_emitter_error(emitter,
+                "tag handle must start with '!'");
+    }
+
+    if (handle.end[-1] != '!') {
+        return yaml_emitter_set_emitter_error(emitter,
+                "tag handle must end with '!'");
+    }
+
+    handle.pointer ++;
+
+    while (handle.pointer < handle.end-1) {
+        if (!IS_ALPHA(handle)) {
+            return yaml_emitter_set_emitter_error(emitter,
+                    "tag handle must contain alphanumerical characters only");
+        }
+        MOVE(handle);
+    }
+
+    if (prefix.start == prefix.end) {
+        return yaml_emitter_set_emitter_error(emitter,
+                "tag prefix must not be empty");
+    }
+
+    return 1;
+}
+
+/*
+ * Check if an anchor is valid.
+ */
+
+static int
+yaml_emitter_analyze_anchor(yaml_emitter_t *emitter,
+        yaml_char_t *anchor, int alias)
+{
+    size_t anchor_length;
+    yaml_string_t string;
+
+    anchor_length = strlen((char *)anchor);
+    STRING_ASSIGN(string, anchor, anchor_length);
+
+    if (string.start == string.end) {
+        return yaml_emitter_set_emitter_error(emitter, alias ?
+                "alias value must not be empty" :
+                "anchor value must not be empty");
+    }
+
+    while (string.pointer != string.end) {
+        if (!IS_ALPHA(string)) {
+            return yaml_emitter_set_emitter_error(emitter, alias ?
+                    "alias value must contain alphanumerical characters only" :
+                    "anchor value must contain alphanumerical characters only");
+        }
+        MOVE(string);
+    }
+
+    emitter->anchor_data.anchor = string.start;
+    emitter->anchor_data.anchor_length = string.end - string.start;
+    emitter->anchor_data.alias = alias;
+
+    return 1;
+}
+
+/*
+ * Check if a tag is valid.
+ */
+
+static int
+yaml_emitter_analyze_tag(yaml_emitter_t *emitter,
+        yaml_char_t *tag)
+{
+    size_t tag_length;
+    yaml_string_t string;
+    yaml_tag_directive_t *tag_directive;
+
+    tag_length = strlen((char *)tag);
+    STRING_ASSIGN(string, tag, tag_length);
+
+    if (string.start == string.end) {
+        return yaml_emitter_set_emitter_error(emitter,
+                "tag value must not be empty");
+    }
+
+    for (tag_directive = emitter->tag_directives.start;
+            tag_directive != emitter->tag_directives.top; tag_directive ++) {
+        size_t prefix_length = strlen((char *)tag_directive->prefix);
+        if (prefix_length < (size_t)(string.end - string.start)
+                && strncmp((char *)tag_directive->prefix, (char *)string.start,
+                    prefix_length) == 0)
+        {
+            emitter->tag_data.handle = tag_directive->handle;
+            emitter->tag_data.handle_length =
+                strlen((char *)tag_directive->handle);
+            emitter->tag_data.suffix = string.start + prefix_length;
+            emitter->tag_data.suffix_length =
+                (string.end - string.start) - prefix_length;
+            return 1;
+        }
+    }
+
+    emitter->tag_data.suffix = string.start;
+    emitter->tag_data.suffix_length = string.end - string.start;
+
+    return 1;
+}
+
+/*
+ * Check if a scalar is valid.
+ */
+
+static int
+yaml_emitter_analyze_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length)
+{
+    yaml_string_t string;
+
+    int block_indicators = 0;
+    int flow_indicators = 0;
+    int line_breaks = 0;
+    int special_characters = 0;
+
+    int leading_space = 0;
+    int leading_break = 0;
+    int trailing_space = 0;
+    int trailing_break = 0;
+    int break_space = 0;
+    int space_break = 0;
+
+    int preceded_by_whitespace = 0;
+    int followed_by_whitespace = 0;
+    int previous_space = 0;
+    int previous_break = 0;
+
+    STRING_ASSIGN(string, value, length);
+
+    emitter->scalar_data.value = value;
+    emitter->scalar_data.length = length;
+
+    if (string.start == string.end)
+    {
+        emitter->scalar_data.multiline = 0;
+        emitter->scalar_data.flow_plain_allowed = 0;
+        emitter->scalar_data.block_plain_allowed = 1;
+        emitter->scalar_data.single_quoted_allowed = 1;
+        emitter->scalar_data.block_allowed = 0;
+
+        return 1;
+    }
+
+    if ((CHECK_AT(string, '-', 0)
+                && CHECK_AT(string, '-', 1)
+                && CHECK_AT(string, '-', 2))
+            || (CHECK_AT(string, '.', 0)
+                && CHECK_AT(string, '.', 1)
+                && CHECK_AT(string, '.', 2))) {
+        block_indicators = 1;
+        flow_indicators = 1;
+    }
+
+    preceded_by_whitespace = 1;
+    followed_by_whitespace = IS_BLANKZ_AT(string, WIDTH(string));
+
+    while (string.pointer != string.end)
+    {
+        if (string.start == string.pointer)
+        {
+            if (CHECK(string, '#') || CHECK(string, ',')
+                    || CHECK(string, '[') || CHECK(string, ']')
+                    || CHECK(string, '{') || CHECK(string, '}')
+                    || CHECK(string, '&') || CHECK(string, '*')
+                    || CHECK(string, '!') || CHECK(string, '|')
+                    || CHECK(string, '>') || CHECK(string, '\'')
+                    || CHECK(string, '"') || CHECK(string, '%')
+                    || CHECK(string, '@') || CHECK(string, '`')) {
+                flow_indicators = 1;
+                block_indicators = 1;
+            }
+
+            if (CHECK(string, '?') || CHECK(string, ':')) {
+                flow_indicators = 1;
+                if (followed_by_whitespace) {
+                    block_indicators = 1;
+                }
+            }
+
+            if (CHECK(string, '-') && followed_by_whitespace) {
+                flow_indicators = 1;
+                block_indicators = 1;
+            }
+        }
+        else
+        {
+            if (CHECK(string, ',') || CHECK(string, '?')
+                    || CHECK(string, '[') || CHECK(string, ']')
+                    || CHECK(string, '{') || CHECK(string, '}')) {
+                flow_indicators = 1;
+            }
+
+            if (CHECK(string, ':')) {
+                flow_indicators = 1;
+                if (followed_by_whitespace) {
+                    block_indicators = 1;
+                }
+            }
+
+            if (CHECK(string, '#') && preceded_by_whitespace) {
+                flow_indicators = 1;
+                block_indicators = 1;
+            }
+        }
+
+        if (!IS_PRINTABLE(string)
+                || (!IS_ASCII(string) && !emitter->unicode)) {
+            special_characters = 1;
+        }
+
+        if (IS_BREAK(string)) {
+            line_breaks = 1;
+        }
+
+        if (IS_SPACE(string))
+        {
+            if (string.start == string.pointer) {
+                leading_space = 1;
+            }
+            if (string.pointer+WIDTH(string) == string.end) {
+                trailing_space = 1;
+            }
+            if (previous_break) {
+                break_space = 1;
+            }
+            previous_space = 1;
+            previous_break = 0;
+        }
+        else if (IS_BREAK(string))
+        {
+            if (string.start == string.pointer) {
+                leading_break = 1;
+            }
+            if (string.pointer+WIDTH(string) == string.end) {
+                trailing_break = 1;
+            }
+            if (previous_space) {
+                space_break = 1;
+            }
+            previous_space = 0;
+            previous_break = 1;
+        }
+        else
+        {
+            previous_space = 0;
+            previous_break = 0;
+        }
+
+        preceded_by_whitespace = IS_BLANKZ(string);
+        MOVE(string);
+        if (string.pointer != string.end) {
+            followed_by_whitespace = IS_BLANKZ_AT(string, WIDTH(string));
+        }
+    }
+
+    emitter->scalar_data.multiline = line_breaks;
+
+    emitter->scalar_data.flow_plain_allowed = 1;
+    emitter->scalar_data.block_plain_allowed = 1;
+    emitter->scalar_data.single_quoted_allowed = 1;
+    emitter->scalar_data.block_allowed = 1;
+
+    if (leading_space || leading_break || trailing_space || trailing_break) {
+        emitter->scalar_data.flow_plain_allowed = 0;
+        emitter->scalar_data.block_plain_allowed = 0;
+    }
+
+    if (trailing_space) {
+        emitter->scalar_data.block_allowed = 0;
+    }
+
+    if (break_space) {
+        emitter->scalar_data.flow_plain_allowed = 0;
+        emitter->scalar_data.block_plain_allowed = 0;
+        emitter->scalar_data.single_quoted_allowed = 0;
+    }
+
+    if (space_break || special_characters) {
+        emitter->scalar_data.flow_plain_allowed = 0;
+        emitter->scalar_data.block_plain_allowed = 0;
+        emitter->scalar_data.single_quoted_allowed = 0;
+        emitter->scalar_data.block_allowed = 0;
+    }
+
+    if (line_breaks) {
+        emitter->scalar_data.flow_plain_allowed = 0;
+        emitter->scalar_data.block_plain_allowed = 0;
+    }
+
+    if (flow_indicators) {
+        emitter->scalar_data.flow_plain_allowed = 0;
+    }
+
+    if (block_indicators) {
+        emitter->scalar_data.block_plain_allowed = 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Check if the event data is valid.
+ */
+
+static int
+yaml_emitter_analyze_event(yaml_emitter_t *emitter,
+        yaml_event_t *event)
+{
+    emitter->anchor_data.anchor = NULL;
+    emitter->anchor_data.anchor_length = 0;
+    emitter->tag_data.handle = NULL;
+    emitter->tag_data.handle_length = 0;
+    emitter->tag_data.suffix = NULL;
+    emitter->tag_data.suffix_length = 0;
+    emitter->scalar_data.value = NULL;
+    emitter->scalar_data.length = 0;
+
+    switch (event->type)
+    {
+        case YAML_ALIAS_EVENT:
+            if (!yaml_emitter_analyze_anchor(emitter,
+                        event->data.alias.anchor, 1))
+                return 0;
+            return 1;
+
+        case YAML_SCALAR_EVENT:
+            if (event->data.scalar.anchor) {
+                if (!yaml_emitter_analyze_anchor(emitter,
+                            event->data.scalar.anchor, 0))
+                    return 0;
+            }
+            if (event->data.scalar.tag && (emitter->canonical ||
+                        (!event->data.scalar.plain_implicit
+                         && !event->data.scalar.quoted_implicit))) {
+                if (!yaml_emitter_analyze_tag(emitter, event->data.scalar.tag))
+                    return 0;
+            }
+            if (!yaml_emitter_analyze_scalar(emitter,
+                        event->data.scalar.value, event->data.scalar.length))
+                return 0;
+            return 1;
+
+        case YAML_SEQUENCE_START_EVENT:
+            if (event->data.sequence_start.anchor) {
+                if (!yaml_emitter_analyze_anchor(emitter,
+                            event->data.sequence_start.anchor, 0))
+                    return 0;
+            }
+            if (event->data.sequence_start.tag && (emitter->canonical ||
+                        !event->data.sequence_start.implicit)) {
+                if (!yaml_emitter_analyze_tag(emitter,
+                            event->data.sequence_start.tag))
+                    return 0;
+            }
+            return 1;
+
+        case YAML_MAPPING_START_EVENT:
+            if (event->data.mapping_start.anchor) {
+                if (!yaml_emitter_analyze_anchor(emitter,
+                            event->data.mapping_start.anchor, 0))
+                    return 0;
+            }
+            if (event->data.mapping_start.tag && (emitter->canonical ||
+                        !event->data.mapping_start.implicit)) {
+                if (!yaml_emitter_analyze_tag(emitter,
+                            event->data.mapping_start.tag))
+                    return 0;
+            }
+            return 1;
+
+        default:
+            return 1;
+    }
+}
+
+/*
+ * Write the BOM character.
+ */
+
+static int
+yaml_emitter_write_bom(yaml_emitter_t *emitter)
+{
+    if (!FLUSH(emitter)) return 0;
+
+    *(emitter->buffer.pointer++) = (yaml_char_t) '\xEF';
+    *(emitter->buffer.pointer++) = (yaml_char_t) '\xBB';
+    *(emitter->buffer.pointer++) = (yaml_char_t) '\xBF';
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_indent(yaml_emitter_t *emitter)
+{
+    int indent = (emitter->indent >= 0) ? emitter->indent : 0;
+
+    if (!emitter->indention || emitter->column > indent
+            || (emitter->column == indent && !emitter->whitespace)) {
+        if (!PUT_BREAK(emitter)) return 0;
+    }
+
+    while (emitter->column < indent) {
+        if (!PUT(emitter, ' ')) return 0;
+    }
+
+    emitter->whitespace = 1;
+    emitter->indention = 1;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_indicator(yaml_emitter_t *emitter,
+        const char *indicator, int need_whitespace,
+        int is_whitespace, int is_indention)
+{
+    size_t indicator_length;
+    yaml_string_t string;
+
+    indicator_length = strlen(indicator);
+    STRING_ASSIGN(string, (yaml_char_t *)indicator, indicator_length);
+
+    if (need_whitespace && !emitter->whitespace) {
+        if (!PUT(emitter, ' ')) return 0;
+    }
+
+    while (string.pointer != string.end) {
+        if (!WRITE(emitter, string)) return 0;
+    }
+
+    emitter->whitespace = is_whitespace;
+    emitter->indention = (emitter->indention && is_indention);
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_anchor(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length)
+{
+    yaml_string_t string;
+    STRING_ASSIGN(string, value, length);
+
+    while (string.pointer != string.end) {
+        if (!WRITE(emitter, string)) return 0;
+    }
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_tag_handle(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length)
+{
+    yaml_string_t string;
+    STRING_ASSIGN(string, value, length);
+
+    if (!emitter->whitespace) {
+        if (!PUT(emitter, ' ')) return 0;
+    }
+
+    while (string.pointer != string.end) {
+        if (!WRITE(emitter, string)) return 0;
+    }
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_tag_content(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length,
+        int need_whitespace)
+{
+    yaml_string_t string;
+    STRING_ASSIGN(string, value, length);
+
+    if (need_whitespace && !emitter->whitespace) {
+        if (!PUT(emitter, ' ')) return 0;
+    }
+
+    while (string.pointer != string.end) {
+        if (IS_ALPHA(string)
+                || CHECK(string, ';') || CHECK(string, '/')
+                || CHECK(string, '?') || CHECK(string, ':')
+                || CHECK(string, '@') || CHECK(string, '&')
+                || CHECK(string, '=') || CHECK(string, '+')
+                || CHECK(string, '$') || CHECK(string, ',')
+                || CHECK(string, '_') || CHECK(string, '.')
+                || CHECK(string, '~') || CHECK(string, '*')
+                || CHECK(string, '\'') || CHECK(string, '(')
+                || CHECK(string, ')') || CHECK(string, '[')
+                || CHECK(string, ']')) {
+            if (!WRITE(emitter, string)) return 0;
+        }
+        else {
+            int width = WIDTH(string);
+            unsigned int value;
+            while (width --) {
+                value = *(string.pointer++);
+                if (!PUT(emitter, '%')) return 0;
+                if (!PUT(emitter, (value >> 4)
+                            + ((value >> 4) < 10 ? '0' : 'A' - 10)))
+                    return 0;
+                if (!PUT(emitter, (value & 0x0F)
+                            + ((value & 0x0F) < 10 ? '0' : 'A' - 10)))
+                    return 0;
+            }
+        }
+    }
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_plain_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks)
+{
+    yaml_string_t string;
+    int spaces = 0;
+    int breaks = 0;
+
+    STRING_ASSIGN(string, value, length);
+
+    /**
+     * Avoid trailing spaces for empty values in block mode.
+     * In flow mode, we still want the space to prevent ambiguous things
+     * like {a:}.
+     * Currently, the emitter forbids any plain empty scalar in flow mode
+     * (e.g. it outputs {a: ''} instead), so emitter->flow_level will
+     * never be true here.
+     * But if the emitter is ever changed to allow emitting empty values,
+     * the check for flow_level is already here.
+     */
+    if (!emitter->whitespace && (length || emitter->flow_level)) {
+        if (!PUT(emitter, ' ')) return 0;
+    }
+
+    while (string.pointer != string.end)
+    {
+        if (IS_SPACE(string))
+        {
+            if (allow_breaks && !spaces
+                    && emitter->column > emitter->best_width
+                    && !IS_SPACE_AT(string, 1)) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+                MOVE(string);
+            }
+            else {
+                if (!WRITE(emitter, string)) return 0;
+            }
+            spaces = 1;
+        }
+        else if (IS_BREAK(string))
+        {
+            if (!breaks && CHECK(string, '\n')) {
+                if (!PUT_BREAK(emitter)) return 0;
+            }
+            if (!WRITE_BREAK(emitter, string)) return 0;
+            emitter->indention = 1;
+            breaks = 1;
+        }
+        else
+        {
+            if (breaks) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+            }
+            if (!WRITE(emitter, string)) return 0;
+            emitter->indention = 0;
+            spaces = 0;
+            breaks = 0;
+        }
+    }
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_single_quoted_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks)
+{
+    yaml_string_t string;
+    int spaces = 0;
+    int breaks = 0;
+
+    STRING_ASSIGN(string, value, length);
+
+    if (!yaml_emitter_write_indicator(emitter, "'", 1, 0, 0))
+        return 0;
+
+    while (string.pointer != string.end)
+    {
+        if (IS_SPACE(string))
+        {
+            if (allow_breaks && !spaces
+                    && emitter->column > emitter->best_width
+                    && string.pointer != string.start
+                    && string.pointer != string.end - 1
+                    && !IS_SPACE_AT(string, 1)) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+                MOVE(string);
+            }
+            else {
+                if (!WRITE(emitter, string)) return 0;
+            }
+            spaces = 1;
+        }
+        else if (IS_BREAK(string))
+        {
+            if (!breaks && CHECK(string, '\n')) {
+                if (!PUT_BREAK(emitter)) return 0;
+            }
+            if (!WRITE_BREAK(emitter, string)) return 0;
+            emitter->indention = 1;
+            breaks = 1;
+        }
+        else
+        {
+            if (breaks) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+            }
+            if (CHECK(string, '\'')) {
+                if (!PUT(emitter, '\'')) return 0;
+            }
+            if (!WRITE(emitter, string)) return 0;
+            emitter->indention = 0;
+            spaces = 0;
+            breaks = 0;
+        }
+    }
+
+    if (breaks)
+        if (!yaml_emitter_write_indent(emitter)) return 0;
+
+    if (!yaml_emitter_write_indicator(emitter, "'", 0, 0, 0))
+        return 0;
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_double_quoted_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length, int allow_breaks)
+{
+    yaml_string_t string;
+    int spaces = 0;
+
+    STRING_ASSIGN(string, value, length);
+
+    if (!yaml_emitter_write_indicator(emitter, "\"", 1, 0, 0))
+        return 0;
+
+    while (string.pointer != string.end)
+    {
+        if (!IS_PRINTABLE(string) || (!emitter->unicode && !IS_ASCII(string))
+                || IS_BOM(string) || IS_BREAK(string)
+                || CHECK(string, '"') || CHECK(string, '\\'))
+        {
+            unsigned char octet;
+            unsigned int width;
+            unsigned int value;
+            int k;
+
+            octet = string.pointer[0];
+            width = (octet & 0x80) == 0x00 ? 1 :
+                    (octet & 0xE0) == 0xC0 ? 2 :
+                    (octet & 0xF0) == 0xE0 ? 3 :
+                    (octet & 0xF8) == 0xF0 ? 4 : 0;
+            value = (octet & 0x80) == 0x00 ? octet & 0x7F :
+                    (octet & 0xE0) == 0xC0 ? octet & 0x1F :
+                    (octet & 0xF0) == 0xE0 ? octet & 0x0F :
+                    (octet & 0xF8) == 0xF0 ? octet & 0x07 : 0;
+            for (k = 1; k < (int)width; k ++) {
+                octet = string.pointer[k];
+                value = (value << 6) + (octet & 0x3F);
+            }
+            string.pointer += width;
+
+            if (!PUT(emitter, '\\')) return 0;
+
+            switch (value)
+            {
+                case 0x00:
+                    if (!PUT(emitter, '0')) return 0;
+                    break;
+
+                case 0x07:
+                    if (!PUT(emitter, 'a')) return 0;
+                    break;
+
+                case 0x08:
+                    if (!PUT(emitter, 'b')) return 0;
+                    break;
+
+                case 0x09:
+                    if (!PUT(emitter, 't')) return 0;
+                    break;
+
+                case 0x0A:
+                    if (!PUT(emitter, 'n')) return 0;
+                    break;
+
+                case 0x0B:
+                    if (!PUT(emitter, 'v')) return 0;
+                    break;
+
+                case 0x0C:
+                    if (!PUT(emitter, 'f')) return 0;
+                    break;
+
+                case 0x0D:
+                    if (!PUT(emitter, 'r')) return 0;
+                    break;
+
+                case 0x1B:
+                    if (!PUT(emitter, 'e')) return 0;
+                    break;
+
+                case 0x22:
+                    if (!PUT(emitter, '\"')) return 0;
+                    break;
+
+                case 0x5C:
+                    if (!PUT(emitter, '\\')) return 0;
+                    break;
+
+                case 0x85:
+                    if (!PUT(emitter, 'N')) return 0;
+                    break;
+
+                case 0xA0:
+                    if (!PUT(emitter, '_')) return 0;
+                    break;
+
+                case 0x2028:
+                    if (!PUT(emitter, 'L')) return 0;
+                    break;
+
+                case 0x2029:
+                    if (!PUT(emitter, 'P')) return 0;
+                    break;
+
+                default:
+                    if (value <= 0xFF) {
+                        if (!PUT(emitter, 'x')) return 0;
+                        width = 2;
+                    }
+                    else if (value <= 0xFFFF) {
+                        if (!PUT(emitter, 'u')) return 0;
+                        width = 4;
+                    }
+                    else {
+                        if (!PUT(emitter, 'U')) return 0;
+                        width = 8;
+                    }
+                    for (k = (width-1)*4; k >= 0; k -= 4) {
+                        int digit = (value >> k) & 0x0F;
+                        if (!PUT(emitter, digit + (digit < 10 ? '0' : 'A'-10)))
+                            return 0;
+                    }
+            }
+            spaces = 0;
+        }
+        else if (IS_SPACE(string))
+        {
+            if (allow_breaks && !spaces
+                    && emitter->column > emitter->best_width
+                    && string.pointer != string.start
+                    && string.pointer != string.end - 1) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+                if (IS_SPACE_AT(string, 1)) {
+                    if (!PUT(emitter, '\\')) return 0;
+                }
+                MOVE(string);
+            }
+            else {
+                if (!WRITE(emitter, string)) return 0;
+            }
+            spaces = 1;
+        }
+        else
+        {
+            if (!WRITE(emitter, string)) return 0;
+            spaces = 0;
+        }
+    }
+
+    if (!yaml_emitter_write_indicator(emitter, "\"", 0, 0, 0))
+        return 0;
+
+    emitter->whitespace = 0;
+    emitter->indention = 0;
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_block_scalar_hints(yaml_emitter_t *emitter,
+        yaml_string_t string)
+{
+    char indent_hint[2];
+    const char *chomp_hint = NULL;
+
+    if (IS_SPACE(string) || IS_BREAK(string))
+    {
+        indent_hint[0] = '0' + (char)emitter->best_indent;
+        indent_hint[1] = '\0';
+        if (!yaml_emitter_write_indicator(emitter, indent_hint, 0, 0, 0))
+            return 0;
+    }
+
+    emitter->open_ended = 0;
+
+    string.pointer = string.end;
+    if (string.start == string.pointer)
+    {
+        chomp_hint = "-";
+    }
+    else
+    {
+        do {
+            string.pointer --;
+        } while ((*string.pointer & 0xC0) == 0x80);
+        if (!IS_BREAK(string))
+        {
+            chomp_hint = "-";
+        }
+        else if (string.start == string.pointer)
+        {
+            chomp_hint = "+";
+            emitter->open_ended = 2;
+        }
+        else
+        {
+            do {
+                string.pointer --;
+            } while ((*string.pointer & 0xC0) == 0x80);
+            if (IS_BREAK(string))
+            {
+                chomp_hint = "+";
+                emitter->open_ended = 2;
+            }
+        }
+    }
+
+    if (chomp_hint)
+    {
+        if (!yaml_emitter_write_indicator(emitter, chomp_hint, 0, 0, 0))
+            return 0;
+    }
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_literal_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length)
+{
+    yaml_string_t string;
+    int breaks = 1;
+
+    STRING_ASSIGN(string, value, length);
+
+    if (!yaml_emitter_write_indicator(emitter, "|", 1, 0, 0))
+        return 0;
+    if (!yaml_emitter_write_block_scalar_hints(emitter, string))
+        return 0;
+    if (!PUT_BREAK(emitter)) return 0;
+    emitter->indention = 1;
+    emitter->whitespace = 1;
+
+    while (string.pointer != string.end)
+    {
+        if (IS_BREAK(string))
+        {
+            if (!WRITE_BREAK(emitter, string)) return 0;
+            emitter->indention = 1;
+            breaks = 1;
+        }
+        else
+        {
+            if (breaks) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+            }
+            if (!WRITE(emitter, string)) return 0;
+            emitter->indention = 0;
+            breaks = 0;
+        }
+    }
+
+    return 1;
+}
+
+static int
+yaml_emitter_write_folded_scalar(yaml_emitter_t *emitter,
+        yaml_char_t *value, size_t length)
+{
+    yaml_string_t string;
+    int breaks = 1;
+    int leading_spaces = 1;
+
+    STRING_ASSIGN(string, value, length);
+
+    if (!yaml_emitter_write_indicator(emitter, ">", 1, 0, 0))
+        return 0;
+    if (!yaml_emitter_write_block_scalar_hints(emitter, string))
+        return 0;
+    if (!PUT_BREAK(emitter)) return 0;
+    emitter->indention = 1;
+    emitter->whitespace = 1;
+
+    while (string.pointer != string.end)
+    {
+        if (IS_BREAK(string))
+        {
+            if (!breaks && !leading_spaces && CHECK(string, '\n')) {
+                int k = 0;
+                while (IS_BREAK_AT(string, k)) {
+                    k += WIDTH_AT(string, k);
+                }
+                if (!IS_BLANKZ_AT(string, k)) {
+                    if (!PUT_BREAK(emitter)) return 0;
+                }
+            }
+            if (!WRITE_BREAK(emitter, string)) return 0;
+            emitter->indention = 1;
+            breaks = 1;
+        }
+        else
+        {
+            if (breaks) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+                leading_spaces = IS_BLANK(string);
+            }
+            if (!breaks && IS_SPACE(string) && !IS_SPACE_AT(string, 1)
+                    && emitter->column > emitter->best_width) {
+                if (!yaml_emitter_write_indent(emitter)) return 0;
+                MOVE(string);
+            }
+            else {
+                if (!WRITE(emitter, string)) return 0;
+            }
+            emitter->indention = 0;
+            breaks = 0;
+        }
+    }
+
+    return 1;
+}
diff --git a/contrib/libs/yaml/src/loader.c b/contrib/libs/yaml/src/loader.c
new file mode 100644
index 0000000000..dea8ac428c
--- /dev/null
+++ b/contrib/libs/yaml/src/loader.c
@@ -0,0 +1,544 @@
+
+#include "yaml_private.h"
+
+/*
+ * API functions.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_load(yaml_parser_t *parser, yaml_document_t *document);
+
+/*
+ * Error handling.
+ */
+
+static int
+yaml_parser_set_composer_error(yaml_parser_t *parser,
+        const char *problem, yaml_mark_t problem_mark);
+
+static int
+yaml_parser_set_composer_error_context(yaml_parser_t *parser,
+        const char *context, yaml_mark_t context_mark,
+        const char *problem, yaml_mark_t problem_mark);
+
+
+/*
+ * Alias handling.
+ */
+
+static int
+yaml_parser_register_anchor(yaml_parser_t *parser,
+        int index, yaml_char_t *anchor);
+
+/*
+ * Clean up functions.
+ */
+
+static void
+yaml_parser_delete_aliases(yaml_parser_t *parser);
+
+/*
+ * Document loading context.
+ */
+struct loader_ctx {
+    int *start;
+    int *end;
+    int *top;
+};
+
+/*
+ * Composer functions.
+ */
+static int
+yaml_parser_load_nodes(yaml_parser_t *parser, struct loader_ctx *ctx);
+
+static int
+yaml_parser_load_document(yaml_parser_t *parser, yaml_event_t *event);
+
+static int
+yaml_parser_load_alias(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx);
+
+static int
+yaml_parser_load_scalar(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx);
+
+static int
+yaml_parser_load_sequence(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx);
+
+static int
+yaml_parser_load_mapping(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx);
+
+static int
+yaml_parser_load_sequence_end(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx);
+
+static int
+yaml_parser_load_mapping_end(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx);
+
+/*
+ * Load the next document of the stream.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_load(yaml_parser_t *parser, yaml_document_t *document)
+{
+    yaml_event_t event;
+
+    assert(parser);     /* Non-NULL parser object is expected. */
+    assert(document);   /* Non-NULL document object is expected. */
+
+    memset(document, 0, sizeof(yaml_document_t));
+    if (!STACK_INIT(parser, document->nodes, yaml_node_t*))
+        goto error;
+
+    if (!parser->stream_start_produced) {
+        if (!yaml_parser_parse(parser, &event)) goto error;
+        assert(event.type == YAML_STREAM_START_EVENT);
+                        /* STREAM-START is expected. */
+    }
+
+    if (parser->stream_end_produced) {
+        return 1;
+    }
+
+    if (!yaml_parser_parse(parser, &event)) goto error;
+    if (event.type == YAML_STREAM_END_EVENT) {
+        return 1;
+    }
+
+    if (!STACK_INIT(parser, parser->aliases, yaml_alias_data_t*))
+        goto error;
+
+    parser->document = document;
+
+    if (!yaml_parser_load_document(parser, &event)) goto error;
+
+    yaml_parser_delete_aliases(parser);
+    parser->document = NULL;
+
+    return 1;
+
+error:
+
+    yaml_parser_delete_aliases(parser);
+    yaml_document_delete(document);
+    parser->document = NULL;
+
+    return 0;
+}
+
+/*
+ * Set composer error.
+ */
+
+static int
+yaml_parser_set_composer_error(yaml_parser_t *parser,
+        const char *problem, yaml_mark_t problem_mark)
+{
+    parser->error = YAML_COMPOSER_ERROR;
+    parser->problem = problem;
+    parser->problem_mark = problem_mark;
+
+    return 0;
+}
+
+/*
+ * Set composer error with context.
+ */
+
+static int
+yaml_parser_set_composer_error_context(yaml_parser_t *parser,
+        const char *context, yaml_mark_t context_mark,
+        const char *problem, yaml_mark_t problem_mark)
+{
+    parser->error = YAML_COMPOSER_ERROR;
+    parser->context = context;
+    parser->context_mark = context_mark;
+    parser->problem = problem;
+    parser->problem_mark = problem_mark;
+
+    return 0;
+}
+
+/*
+ * Delete the stack of aliases.
+ */
+
+static void
+yaml_parser_delete_aliases(yaml_parser_t *parser)
+{
+    while (!STACK_EMPTY(parser, parser->aliases)) {
+        yaml_free(POP(parser, parser->aliases).anchor);
+    }
+    STACK_DEL(parser, parser->aliases);
+}
+
+/*
+ * Compose a document object.
+ */
+
+static int
+yaml_parser_load_document(yaml_parser_t *parser, yaml_event_t *event)
+{
+    struct loader_ctx ctx = { NULL, NULL, NULL };
+
+    assert(event->type == YAML_DOCUMENT_START_EVENT);
+                        /* DOCUMENT-START is expected. */
+
+    parser->document->version_directive
+        = event->data.document_start.version_directive;
+    parser->document->tag_directives.start
+        = event->data.document_start.tag_directives.start;
+    parser->document->tag_directives.end
+        = event->data.document_start.tag_directives.end;
+    parser->document->start_implicit
+        = event->data.document_start.implicit;
+    parser->document->start_mark = event->start_mark;
+
+    if (!STACK_INIT(parser, ctx, int*)) return 0;
+    if (!yaml_parser_load_nodes(parser, &ctx)) {
+        STACK_DEL(parser, ctx);
+        return 0;
+    }
+    STACK_DEL(parser, ctx);
+
+    return 1;
+}
+
+/*
+ * Compose a node tree.
+ */
+
+static int
+yaml_parser_load_nodes(yaml_parser_t *parser, struct loader_ctx *ctx)
+{
+    yaml_event_t event;
+
+    do {
+        if (!yaml_parser_parse(parser, &event)) return 0;
+
+        switch (event.type) {
+            case YAML_ALIAS_EVENT:
+                if (!yaml_parser_load_alias(parser, &event, ctx)) return 0;
+                break;
+            case YAML_SCALAR_EVENT:
+                if (!yaml_parser_load_scalar(parser, &event, ctx)) return 0;
+                break;
+            case YAML_SEQUENCE_START_EVENT:
+                if (!yaml_parser_load_sequence(parser, &event, ctx)) return 0;
+                break;
+            case YAML_SEQUENCE_END_EVENT:
+                if (!yaml_parser_load_sequence_end(parser, &event, ctx))
+                    return 0;
+                break;
+            case YAML_MAPPING_START_EVENT:
+                if (!yaml_parser_load_mapping(parser, &event, ctx)) return 0;
+                break;
+            case YAML_MAPPING_END_EVENT:
+                if (!yaml_parser_load_mapping_end(parser, &event, ctx))
+                    return 0;
+                break;
+            default:
+                assert(0);  /* Could not happen. */
+                return 0;
+            case YAML_DOCUMENT_END_EVENT:
+                break;
+        }
+    } while (event.type != YAML_DOCUMENT_END_EVENT);
+
+    parser->document->end_implicit = event.data.document_end.implicit;
+    parser->document->end_mark = event.end_mark;
+
+    return 1;
+}
+
+/*
+ * Add an anchor.
+ */
+
+static int
+yaml_parser_register_anchor(yaml_parser_t *parser,
+        int index, yaml_char_t *anchor)
+{
+    yaml_alias_data_t data;
+    yaml_alias_data_t *alias_data;
+
+    if (!anchor) return 1;
+
+    data.anchor = anchor;
+    data.index = index;
+    data.mark = parser->document->nodes.start[index-1].start_mark;
+
+    for (alias_data = parser->aliases.start;
+            alias_data != parser->aliases.top; alias_data ++) {
+        if (strcmp((char *)alias_data->anchor, (char *)anchor) == 0) {
+            yaml_free(anchor);
+            return yaml_parser_set_composer_error_context(parser,
+                    "found duplicate anchor; first occurrence",
+                    alias_data->mark, "second occurrence", data.mark);
+        }
+    }
+
+    if (!PUSH(parser, parser->aliases, data)) {
+        yaml_free(anchor);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Compose node into its parent in the stree.
+ */
+
+static int
+yaml_parser_load_node_add(yaml_parser_t *parser, struct loader_ctx *ctx,
+        int index)
+{
+    struct yaml_node_s *parent;
+    int parent_index;
+
+    if (STACK_EMPTY(parser, *ctx)) {
+        /* This is the root node, there's no tree to add it to. */
+        return 1;
+    }
+
+    parent_index = *((*ctx).top - 1);
+    parent = &parser->document->nodes.start[parent_index-1];
+
+    switch (parent->type) {
+        case YAML_SEQUENCE_NODE:
+            if (!STACK_LIMIT(parser, parent->data.sequence.items, INT_MAX-1))
+                return 0;
+            if (!PUSH(parser, parent->data.sequence.items, index))
+                return 0;
+            break;
+        case YAML_MAPPING_NODE: {
+            yaml_node_pair_t pair;
+            if (!STACK_EMPTY(parser, parent->data.mapping.pairs)) {
+                yaml_node_pair_t *p = parent->data.mapping.pairs.top - 1;
+                if (p->key != 0 && p->value == 0) {
+                    p->value = index;
+                    break;
+                }
+            }
+
+            pair.key = index;
+            pair.value = 0;
+            if (!STACK_LIMIT(parser, parent->data.mapping.pairs, INT_MAX-1))
+                return 0;
+            if (!PUSH(parser, parent->data.mapping.pairs, pair))
+                return 0;
+
+            break;
+        }
+        default:
+            assert(0); /* Could not happen. */
+            return 0;
+    }
+    return 1;
+}
+
+/*
+ * Compose a node corresponding to an alias.
+ */
+
+static int
+yaml_parser_load_alias(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx)
+{
+    yaml_char_t *anchor = event->data.alias.anchor;
+    yaml_alias_data_t *alias_data;
+
+    for (alias_data = parser->aliases.start;
+            alias_data != parser->aliases.top; alias_data ++) {
+        if (strcmp((char *)alias_data->anchor, (char *)anchor) == 0) {
+            yaml_free(anchor);
+            return yaml_parser_load_node_add(parser, ctx, alias_data->index);
+        }
+    }
+
+    yaml_free(anchor);
+    return yaml_parser_set_composer_error(parser, "found undefined alias",
+            event->start_mark);
+}
+
+/*
+ * Compose a scalar node.
+ */
+
+static int
+yaml_parser_load_scalar(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx)
+{
+    yaml_node_t node;
+    int index;
+    yaml_char_t *tag = event->data.scalar.tag;
+
+    if (!STACK_LIMIT(parser, parser->document->nodes, INT_MAX-1)) goto error;
+
+    if (!tag || strcmp((char *)tag, "!") == 0) {
+        yaml_free(tag);
+        tag = yaml_strdup((yaml_char_t *)YAML_DEFAULT_SCALAR_TAG);
+        if (!tag) goto error;
+    }
+
+    SCALAR_NODE_INIT(node, tag, event->data.scalar.value,
+            event->data.scalar.length, event->data.scalar.style,
+            event->start_mark, event->end_mark);
+
+    if (!PUSH(parser, parser->document->nodes, node)) goto error;
+
+    index = parser->document->nodes.top - parser->document->nodes.start;
+
+    if (!yaml_parser_register_anchor(parser, index,
+                event->data.scalar.anchor)) return 0;
+
+    return yaml_parser_load_node_add(parser, ctx, index);
+
+error:
+    yaml_free(tag);
+    yaml_free(event->data.scalar.anchor);
+    yaml_free(event->data.scalar.value);
+    return 0;
+}
+
+/*
+ * Compose a sequence node.
+ */
+
+static int
+yaml_parser_load_sequence(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx)
+{
+    yaml_node_t node;
+    struct {
+        yaml_node_item_t *start;
+        yaml_node_item_t *end;
+        yaml_node_item_t *top;
+    } items = { NULL, NULL, NULL };
+    int index;
+    yaml_char_t *tag = event->data.sequence_start.tag;
+
+    if (!STACK_LIMIT(parser, parser->document->nodes, INT_MAX-1)) goto error;
+
+    if (!tag || strcmp((char *)tag, "!") == 0) {
+        yaml_free(tag);
+        tag = yaml_strdup((yaml_char_t *)YAML_DEFAULT_SEQUENCE_TAG);
+        if (!tag) goto error;
+    }
+
+    if (!STACK_INIT(parser, items, yaml_node_item_t*)) goto error;
+
+    SEQUENCE_NODE_INIT(node, tag, items.start, items.end,
+            event->data.sequence_start.style,
+            event->start_mark, event->end_mark);
+
+    if (!PUSH(parser, parser->document->nodes, node)) goto error;
+
+    index = parser->document->nodes.top - parser->document->nodes.start;
+
+    if (!yaml_parser_register_anchor(parser, index,
+                event->data.sequence_start.anchor)) return 0;
+
+    if (!yaml_parser_load_node_add(parser, ctx, index)) return 0;
+
+    if (!STACK_LIMIT(parser, *ctx, INT_MAX-1)) return 0;
+    if (!PUSH(parser, *ctx, index)) return 0;
+
+    return 1;
+
+error:
+    yaml_free(tag);
+    yaml_free(event->data.sequence_start.anchor);
+    return 0;
+}
+
+static int
+yaml_parser_load_sequence_end(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx)
+{
+    int index;
+
+    assert(((*ctx).top - (*ctx).start) > 0);
+
+    index = *((*ctx).top - 1);
+    assert(parser->document->nodes.start[index-1].type == YAML_SEQUENCE_NODE);
+    parser->document->nodes.start[index-1].end_mark = event->end_mark;
+
+    (void)POP(parser, *ctx);
+
+    return 1;
+}
+
+/*
+ * Compose a mapping node.
+ */
+
+static int
+yaml_parser_load_mapping(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx)
+{
+    yaml_node_t node;
+    struct {
+        yaml_node_pair_t *start;
+        yaml_node_pair_t *end;
+        yaml_node_pair_t *top;
+    } pairs = { NULL, NULL, NULL };
+    int index;
+    yaml_char_t *tag = event->data.mapping_start.tag;
+
+    if (!STACK_LIMIT(parser, parser->document->nodes, INT_MAX-1)) goto error;
+
+    if (!tag || strcmp((char *)tag, "!") == 0) {
+        yaml_free(tag);
+        tag = yaml_strdup((yaml_char_t *)YAML_DEFAULT_MAPPING_TAG);
+        if (!tag) goto error;
+    }
+
+    if (!STACK_INIT(parser, pairs, yaml_node_pair_t*)) goto error;
+
+    MAPPING_NODE_INIT(node, tag, pairs.start, pairs.end,
+            event->data.mapping_start.style,
+            event->start_mark, event->end_mark);
+
+    if (!PUSH(parser, parser->document->nodes, node)) goto error;
+
+    index = parser->document->nodes.top - parser->document->nodes.start;
+
+    if (!yaml_parser_register_anchor(parser, index,
+                event->data.mapping_start.anchor)) return 0;
+
+    if (!yaml_parser_load_node_add(parser, ctx, index)) return 0;
+
+    if (!STACK_LIMIT(parser, *ctx, INT_MAX-1)) return 0;
+    if (!PUSH(parser, *ctx, index)) return 0;
+
+    return 1;
+
+error:
+    yaml_free(tag);
+    yaml_free(event->data.mapping_start.anchor);
+    return 0;
+}
+
+static int
+yaml_parser_load_mapping_end(yaml_parser_t *parser, yaml_event_t *event,
+        struct loader_ctx *ctx)
+{
+    int index;
+
+    assert(((*ctx).top - (*ctx).start) > 0);
+
+    index = *((*ctx).top - 1);
+    assert(parser->document->nodes.start[index-1].type == YAML_MAPPING_NODE);
+    parser->document->nodes.start[index-1].end_mark = event->end_mark;
+
+    (void)POP(parser, *ctx);
+
+    return 1;
+}
\ No newline at end of file
diff --git a/contrib/libs/yaml/src/parser.c b/contrib/libs/yaml/src/parser.c
new file mode 100644
index 0000000000..ec2f8d3e05
--- /dev/null
+++ b/contrib/libs/yaml/src/parser.c
@@ -0,0 +1,1375 @@
+
+/*
+ * The parser implements the following grammar:
+ *
+ * stream               ::= STREAM-START implicit_document? explicit_document* STREAM-END
+ * implicit_document    ::= block_node DOCUMENT-END*
+ * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+ * block_node_or_indentless_sequence    ::=
+ *                          ALIAS
+ *                          | properties (block_content | indentless_block_sequence)?
+ *                          | block_content
+ *                          | indentless_block_sequence
+ * block_node           ::= ALIAS
+ *                          | properties block_content?
+ *                          | block_content
+ * flow_node            ::= ALIAS
+ *                          | properties flow_content?
+ *                          | flow_content
+ * properties           ::= TAG ANCHOR? | ANCHOR TAG?
+ * block_content        ::= block_collection | flow_collection | SCALAR
+ * flow_content         ::= flow_collection | SCALAR
+ * block_collection     ::= block_sequence | block_mapping
+ * flow_collection      ::= flow_sequence | flow_mapping
+ * block_sequence       ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
+ * indentless_sequence  ::= (BLOCK-ENTRY block_node?)+
+ * block_mapping        ::= BLOCK-MAPPING_START
+ *                          ((KEY block_node_or_indentless_sequence?)?
+ *                          (VALUE block_node_or_indentless_sequence?)?)*
+ *                          BLOCK-END
+ * flow_sequence        ::= FLOW-SEQUENCE-START
+ *                          (flow_sequence_entry FLOW-ENTRY)*
+ *                          flow_sequence_entry?
+ *                          FLOW-SEQUENCE-END
+ * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+ * flow_mapping         ::= FLOW-MAPPING-START
+ *                          (flow_mapping_entry FLOW-ENTRY)*
+ *                          flow_mapping_entry?
+ *                          FLOW-MAPPING-END
+ * flow_mapping_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+ */
+
+#include "yaml_private.h"
+
+/*
+ * Peek the next token in the token queue.
+ */
+
+#define PEEK_TOKEN(parser)                                                      \
+    ((parser->token_available || yaml_parser_fetch_more_tokens(parser)) ?       \
+        parser->tokens.head : NULL)
+
+/*
+ * Remove the next token from the queue (must be called after PEEK_TOKEN).
+ */
+
+#define SKIP_TOKEN(parser)                                                      \
+    (parser->token_available = 0,                                               \
+     parser->tokens_parsed ++,                                                  \
+     parser->stream_end_produced =                                              \
+        (parser->tokens.head->type == YAML_STREAM_END_TOKEN),                   \
+     parser->tokens.head ++)
+
+/*
+ * Public API declarations.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_parse(yaml_parser_t *parser, yaml_event_t *event);
+
+/*
+ * Error handling.
+ */
+
+static int
+yaml_parser_set_parser_error(yaml_parser_t *parser,
+        const char *problem, yaml_mark_t problem_mark);
+
+static int
+yaml_parser_set_parser_error_context(yaml_parser_t *parser,
+        const char *context, yaml_mark_t context_mark,
+        const char *problem, yaml_mark_t problem_mark);
+
+/*
+ * State functions.
+ */
+
+static int
+yaml_parser_state_machine(yaml_parser_t *parser, yaml_event_t *event);
+
+static int
+yaml_parser_parse_stream_start(yaml_parser_t *parser, yaml_event_t *event);
+
+static int
+yaml_parser_parse_document_start(yaml_parser_t *parser, yaml_event_t *event,
+        int implicit);
+
+static int
+yaml_parser_parse_document_content(yaml_parser_t *parser, yaml_event_t *event);
+
+static int
+yaml_parser_parse_document_end(yaml_parser_t *parser, yaml_event_t *event);
+
+static int
+yaml_parser_parse_node(yaml_parser_t *parser, yaml_event_t *event,
+        int block, int indentless_sequence);
+
+static int
+yaml_parser_parse_block_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event, int first);
+
+static int
+yaml_parser_parse_indentless_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event);
+
+static int
+yaml_parser_parse_block_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event, int first);
+
+static int
+yaml_parser_parse_block_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event);
+
+static int
+yaml_parser_parse_flow_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event, int first);
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event);
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event);
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_end(yaml_parser_t *parser,
+        yaml_event_t *event);
+
+static int
+yaml_parser_parse_flow_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event, int first);
+
+static int
+yaml_parser_parse_flow_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event, int empty);
+
+/*
+ * Utility functions.
+ */
+
+static int
+yaml_parser_process_empty_scalar(yaml_parser_t *parser,
+        yaml_event_t *event, yaml_mark_t mark);
+
+static int
+yaml_parser_process_directives(yaml_parser_t *parser,
+        yaml_version_directive_t **version_directive_ref,
+        yaml_tag_directive_t **tag_directives_start_ref,
+        yaml_tag_directive_t **tag_directives_end_ref);
+
+static int
+yaml_parser_append_tag_directive(yaml_parser_t *parser,
+        yaml_tag_directive_t value, int allow_duplicates, yaml_mark_t mark);
+
+/*
+ * Get the next event.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_parse(yaml_parser_t *parser, yaml_event_t *event)
+{
+    assert(parser);     /* Non-NULL parser object is expected. */
+    assert(event);      /* Non-NULL event object is expected. */
+
+    /* Erase the event object. */
+
+    memset(event, 0, sizeof(yaml_event_t));
+
+    /* No events after the end of the stream or error. */
+
+    if (parser->stream_end_produced || parser->error ||
+            parser->state == YAML_PARSE_END_STATE) {
+        return 1;
+    }
+
+    /* Generate the next event. */
+
+    return yaml_parser_state_machine(parser, event);
+}
+
+/*
+ * Set parser error.
+ */
+
+static int
+yaml_parser_set_parser_error(yaml_parser_t *parser,
+        const char *problem, yaml_mark_t problem_mark)
+{
+    parser->error = YAML_PARSER_ERROR;
+    parser->problem = problem;
+    parser->problem_mark = problem_mark;
+
+    return 0;
+}
+
+static int
+yaml_parser_set_parser_error_context(yaml_parser_t *parser,
+        const char *context, yaml_mark_t context_mark,
+        const char *problem, yaml_mark_t problem_mark)
+{
+    parser->error = YAML_PARSER_ERROR;
+    parser->context = context;
+    parser->context_mark = context_mark;
+    parser->problem = problem;
+    parser->problem_mark = problem_mark;
+
+    return 0;
+}
+
+
+/*
+ * State dispatcher.
+ */
+
+static int
+yaml_parser_state_machine(yaml_parser_t *parser, yaml_event_t *event)
+{
+    switch (parser->state)
+    {
+        case YAML_PARSE_STREAM_START_STATE:
+            return yaml_parser_parse_stream_start(parser, event);
+
+        case YAML_PARSE_IMPLICIT_DOCUMENT_START_STATE:
+            return yaml_parser_parse_document_start(parser, event, 1);
+
+        case YAML_PARSE_DOCUMENT_START_STATE:
+            return yaml_parser_parse_document_start(parser, event, 0);
+
+        case YAML_PARSE_DOCUMENT_CONTENT_STATE:
+            return yaml_parser_parse_document_content(parser, event);
+
+        case YAML_PARSE_DOCUMENT_END_STATE:
+            return yaml_parser_parse_document_end(parser, event);
+
+        case YAML_PARSE_BLOCK_NODE_STATE:
+            return yaml_parser_parse_node(parser, event, 1, 0);
+
+        case YAML_PARSE_BLOCK_NODE_OR_INDENTLESS_SEQUENCE_STATE:
+            return yaml_parser_parse_node(parser, event, 1, 1);
+
+        case YAML_PARSE_FLOW_NODE_STATE:
+            return yaml_parser_parse_node(parser, event, 0, 0);
+
+        case YAML_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE:
+            return yaml_parser_parse_block_sequence_entry(parser, event, 1);
+
+        case YAML_PARSE_BLOCK_SEQUENCE_ENTRY_STATE:
+            return yaml_parser_parse_block_sequence_entry(parser, event, 0);
+
+        case YAML_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE:
+            return yaml_parser_parse_indentless_sequence_entry(parser, event);
+
+        case YAML_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE:
+            return yaml_parser_parse_block_mapping_key(parser, event, 1);
+
+        case YAML_PARSE_BLOCK_MAPPING_KEY_STATE:
+            return yaml_parser_parse_block_mapping_key(parser, event, 0);
+
+        case YAML_PARSE_BLOCK_MAPPING_VALUE_STATE:
+            return yaml_parser_parse_block_mapping_value(parser, event);
+
+        case YAML_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE:
+            return yaml_parser_parse_flow_sequence_entry(parser, event, 1);
+
+        case YAML_PARSE_FLOW_SEQUENCE_ENTRY_STATE:
+            return yaml_parser_parse_flow_sequence_entry(parser, event, 0);
+
+        case YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE:
+            return yaml_parser_parse_flow_sequence_entry_mapping_key(parser, event);
+
+        case YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE:
+            return yaml_parser_parse_flow_sequence_entry_mapping_value(parser, event);
+
+        case YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE:
+            return yaml_parser_parse_flow_sequence_entry_mapping_end(parser, event);
+
+        case YAML_PARSE_FLOW_MAPPING_FIRST_KEY_STATE:
+            return yaml_parser_parse_flow_mapping_key(parser, event, 1);
+
+        case YAML_PARSE_FLOW_MAPPING_KEY_STATE:
+            return yaml_parser_parse_flow_mapping_key(parser, event, 0);
+
+        case YAML_PARSE_FLOW_MAPPING_VALUE_STATE:
+            return yaml_parser_parse_flow_mapping_value(parser, event, 0);
+
+        case YAML_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE:
+            return yaml_parser_parse_flow_mapping_value(parser, event, 1);
+
+        default:
+            assert(1);      /* Invalid state. */
+    }
+
+    return 0;
+}
+
+/*
+ * Parse the production:
+ * stream   ::= STREAM-START implicit_document? explicit_document* STREAM-END
+ *              ************
+ */
+
+static int
+yaml_parser_parse_stream_start(yaml_parser_t *parser, yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type != YAML_STREAM_START_TOKEN) {
+        return yaml_parser_set_parser_error(parser,
+                "did not find expected <stream-start>", token->start_mark);
+    }
+
+    parser->state = YAML_PARSE_IMPLICIT_DOCUMENT_START_STATE;
+    STREAM_START_EVENT_INIT(*event, token->data.stream_start.encoding,
+            token->start_mark, token->start_mark);
+    SKIP_TOKEN(parser);
+
+    return 1;
+}
+
+/*
+ * Parse the productions:
+ * implicit_document    ::= block_node DOCUMENT-END*
+ *                          *
+ * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+ *                          *************************
+ */
+
+static int
+yaml_parser_parse_document_start(yaml_parser_t *parser, yaml_event_t *event,
+        int implicit)
+{
+    yaml_token_t *token;
+    yaml_version_directive_t *version_directive = NULL;
+    struct {
+        yaml_tag_directive_t *start;
+        yaml_tag_directive_t *end;
+    } tag_directives = { NULL, NULL };
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    /* Parse extra document end indicators. */
+
+    if (!implicit)
+    {
+        while (token->type == YAML_DOCUMENT_END_TOKEN) {
+            SKIP_TOKEN(parser);
+            token = PEEK_TOKEN(parser);
+            if (!token) return 0;
+        }
+    }
+
+    /* Parse an implicit document. */
+
+    if (implicit && token->type != YAML_VERSION_DIRECTIVE_TOKEN &&
+            token->type != YAML_TAG_DIRECTIVE_TOKEN &&
+            token->type != YAML_DOCUMENT_START_TOKEN &&
+            token->type != YAML_STREAM_END_TOKEN)
+    {
+        if (!yaml_parser_process_directives(parser, NULL, NULL, NULL))
+            return 0;
+        if (!PUSH(parser, parser->states, YAML_PARSE_DOCUMENT_END_STATE))
+            return 0;
+        parser->state = YAML_PARSE_BLOCK_NODE_STATE;
+        DOCUMENT_START_EVENT_INIT(*event, NULL, NULL, NULL, 1,
+                token->start_mark, token->start_mark);
+        return 1;
+    }
+
+    /* Parse an explicit document. */
+
+    else if (token->type != YAML_STREAM_END_TOKEN)
+    {
+        yaml_mark_t start_mark, end_mark;
+        start_mark = token->start_mark;
+        if (!yaml_parser_process_directives(parser, &version_directive,
+                    &tag_directives.start, &tag_directives.end))
+            return 0;
+        token = PEEK_TOKEN(parser);
+        if (!token) goto error;
+        if (token->type != YAML_DOCUMENT_START_TOKEN) {
+            yaml_parser_set_parser_error(parser,
+                    "did not find expected <document start>", token->start_mark);
+            goto error;
+        }
+        if (!PUSH(parser, parser->states, YAML_PARSE_DOCUMENT_END_STATE))
+            goto error;
+        parser->state = YAML_PARSE_DOCUMENT_CONTENT_STATE;
+        end_mark = token->end_mark;
+        DOCUMENT_START_EVENT_INIT(*event, version_directive,
+                tag_directives.start, tag_directives.end, 0,
+                start_mark, end_mark);
+        SKIP_TOKEN(parser);
+        version_directive = NULL;
+        tag_directives.start = tag_directives.end = NULL;
+        return 1;
+    }
+
+    /* Parse the stream end. */
+
+    else
+    {
+        parser->state = YAML_PARSE_END_STATE;
+        STREAM_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
+        SKIP_TOKEN(parser);
+        return 1;
+    }
+
+error:
+    yaml_free(version_directive);
+    while (tag_directives.start != tag_directives.end) {
+        yaml_free(tag_directives.end[-1].handle);
+        yaml_free(tag_directives.end[-1].prefix);
+        tag_directives.end --;
+    }
+    yaml_free(tag_directives.start);
+    return 0;
+}
+
+/*
+ * Parse the productions:
+ * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+ *                                                    ***********
+ */
+
+static int
+yaml_parser_parse_document_content(yaml_parser_t *parser, yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_VERSION_DIRECTIVE_TOKEN ||
+            token->type == YAML_TAG_DIRECTIVE_TOKEN ||
+            token->type == YAML_DOCUMENT_START_TOKEN ||
+            token->type == YAML_DOCUMENT_END_TOKEN ||
+            token->type == YAML_STREAM_END_TOKEN) {
+        parser->state = POP(parser, parser->states);
+        return yaml_parser_process_empty_scalar(parser, event,
+                token->start_mark);
+    }
+    else {
+        return yaml_parser_parse_node(parser, event, 1, 0);
+    }
+}
+
+/*
+ * Parse the productions:
+ * implicit_document    ::= block_node DOCUMENT-END*
+ *                                     *************
+ * explicit_document    ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+ *                                                                *************
+ */
+
+static int
+yaml_parser_parse_document_end(yaml_parser_t *parser, yaml_event_t *event)
+{
+    yaml_token_t *token;
+    yaml_mark_t start_mark, end_mark;
+    int implicit = 1;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    start_mark = end_mark = token->start_mark;
+
+    if (token->type == YAML_DOCUMENT_END_TOKEN) {
+        end_mark = token->end_mark;
+        SKIP_TOKEN(parser);
+        implicit = 0;
+    }
+
+    while (!STACK_EMPTY(parser, parser->tag_directives)) {
+        yaml_tag_directive_t tag_directive = POP(parser, parser->tag_directives);
+        yaml_free(tag_directive.handle);
+        yaml_free(tag_directive.prefix);
+    }
+
+    parser->state = YAML_PARSE_DOCUMENT_START_STATE;
+    DOCUMENT_END_EVENT_INIT(*event, implicit, start_mark, end_mark);
+
+    return 1;
+}
+
+/*
+ * Parse the productions:
+ * block_node_or_indentless_sequence    ::=
+ *                          ALIAS
+ *                          *****
+ *                          | properties (block_content | indentless_block_sequence)?
+ *                            **********  *
+ *                          | block_content | indentless_block_sequence
+ *                            *
+ * block_node           ::= ALIAS
+ *                          *****
+ *                          | properties block_content?
+ *                            ********** *
+ *                          | block_content
+ *                            *
+ * flow_node            ::= ALIAS
+ *                          *****
+ *                          | properties flow_content?
+ *                            ********** *
+ *                          | flow_content
+ *                            *
+ * properties           ::= TAG ANCHOR? | ANCHOR TAG?
+ *                          *************************
+ * block_content        ::= block_collection | flow_collection | SCALAR
+ *                                                               ******
+ * flow_content         ::= flow_collection | SCALAR
+ *                                            ******
+ */
+
+static int
+yaml_parser_parse_node(yaml_parser_t *parser, yaml_event_t *event,
+        int block, int indentless_sequence)
+{
+    yaml_token_t *token;
+    yaml_char_t *anchor = NULL;
+    yaml_char_t *tag_handle = NULL;
+    yaml_char_t *tag_suffix = NULL;
+    yaml_char_t *tag = NULL;
+    yaml_mark_t start_mark, end_mark, tag_mark;
+    int implicit;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_ALIAS_TOKEN)
+    {
+        parser->state = POP(parser, parser->states);
+        ALIAS_EVENT_INIT(*event, token->data.alias.value,
+                token->start_mark, token->end_mark);
+        SKIP_TOKEN(parser);
+        return 1;
+    }
+
+    else
+    {
+        start_mark = end_mark = token->start_mark;
+
+        if (token->type == YAML_ANCHOR_TOKEN)
+        {
+            anchor = token->data.anchor.value;
+            start_mark = token->start_mark;
+            end_mark = token->end_mark;
+            SKIP_TOKEN(parser);
+            token = PEEK_TOKEN(parser);
+            if (!token) goto error;
+            if (token->type == YAML_TAG_TOKEN)
+            {
+                tag_handle = token->data.tag.handle;
+                tag_suffix = token->data.tag.suffix;
+                tag_mark = token->start_mark;
+                end_mark = token->end_mark;
+                SKIP_TOKEN(parser);
+                token = PEEK_TOKEN(parser);
+                if (!token) goto error;
+            }
+        }
+        else if (token->type == YAML_TAG_TOKEN)
+        {
+            tag_handle = token->data.tag.handle;
+            tag_suffix = token->data.tag.suffix;
+            start_mark = tag_mark = token->start_mark;
+            end_mark = token->end_mark;
+            SKIP_TOKEN(parser);
+            token = PEEK_TOKEN(parser);
+            if (!token) goto error;
+            if (token->type == YAML_ANCHOR_TOKEN)
+            {
+                anchor = token->data.anchor.value;
+                end_mark = token->end_mark;
+                SKIP_TOKEN(parser);
+                token = PEEK_TOKEN(parser);
+                if (!token) goto error;
+            }
+        }
+
+        if (tag_handle) {
+            if (!*tag_handle) {
+                tag = tag_suffix;
+                yaml_free(tag_handle);
+                tag_handle = tag_suffix = NULL;
+            }
+            else {
+                yaml_tag_directive_t *tag_directive;
+                for (tag_directive = parser->tag_directives.start;
+                        tag_directive != parser->tag_directives.top;
+                        tag_directive ++) {
+                    if (strcmp((char *)tag_directive->handle, (char *)tag_handle) == 0) {
+                        size_t prefix_len = strlen((char *)tag_directive->prefix);
+                        size_t suffix_len = strlen((char *)tag_suffix);
+                        tag = YAML_MALLOC(prefix_len+suffix_len+1);
+                        if (!tag) {
+                            parser->error = YAML_MEMORY_ERROR;
+                            goto error;
+                        }
+                        memcpy(tag, tag_directive->prefix, prefix_len);
+                        memcpy(tag+prefix_len, tag_suffix, suffix_len);
+                        tag[prefix_len+suffix_len] = '\0';
+                        yaml_free(tag_handle);
+                        yaml_free(tag_suffix);
+                        tag_handle = tag_suffix = NULL;
+                        break;
+                    }
+                }
+                if (!tag) {
+                    yaml_parser_set_parser_error_context(parser,
+                            "while parsing a node", start_mark,
+                            "found undefined tag handle", tag_mark);
+                    goto error;
+                }
+            }
+        }
+
+        implicit = (!tag || !*tag);
+        if (indentless_sequence && token->type == YAML_BLOCK_ENTRY_TOKEN) {
+            end_mark = token->end_mark;
+            parser->state = YAML_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE;
+            SEQUENCE_START_EVENT_INIT(*event, anchor, tag, implicit,
+                    YAML_BLOCK_SEQUENCE_STYLE, start_mark, end_mark);
+            return 1;
+        }
+        else {
+            if (token->type == YAML_SCALAR_TOKEN) {
+                int plain_implicit = 0;
+                int quoted_implicit = 0;
+                end_mark = token->end_mark;
+                if ((token->data.scalar.style == YAML_PLAIN_SCALAR_STYLE && !tag)
+                        || (tag && strcmp((char *)tag, "!") == 0)) {
+                    plain_implicit = 1;
+                }
+                else if (!tag) {
+                    quoted_implicit = 1;
+                }
+                parser->state = POP(parser, parser->states);
+                SCALAR_EVENT_INIT(*event, anchor, tag,
+                        token->data.scalar.value, token->data.scalar.length,
+                        plain_implicit, quoted_implicit,
+                        token->data.scalar.style, start_mark, end_mark);
+                SKIP_TOKEN(parser);
+                return 1;
+            }
+            else if (token->type == YAML_FLOW_SEQUENCE_START_TOKEN) {
+                end_mark = token->end_mark;
+                parser->state = YAML_PARSE_FLOW_SEQUENCE_FIRST_ENTRY_STATE;
+                SEQUENCE_START_EVENT_INIT(*event, anchor, tag, implicit,
+                        YAML_FLOW_SEQUENCE_STYLE, start_mark, end_mark);
+                return 1;
+            }
+            else if (token->type == YAML_FLOW_MAPPING_START_TOKEN) {
+                end_mark = token->end_mark;
+                parser->state = YAML_PARSE_FLOW_MAPPING_FIRST_KEY_STATE;
+                MAPPING_START_EVENT_INIT(*event, anchor, tag, implicit,
+                        YAML_FLOW_MAPPING_STYLE, start_mark, end_mark);
+                return 1;
+            }
+            else if (block && token->type == YAML_BLOCK_SEQUENCE_START_TOKEN) {
+                end_mark = token->end_mark;
+                parser->state = YAML_PARSE_BLOCK_SEQUENCE_FIRST_ENTRY_STATE;
+                SEQUENCE_START_EVENT_INIT(*event, anchor, tag, implicit,
+                        YAML_BLOCK_SEQUENCE_STYLE, start_mark, end_mark);
+                return 1;
+            }
+            else if (block && token->type == YAML_BLOCK_MAPPING_START_TOKEN) {
+                end_mark = token->end_mark;
+                parser->state = YAML_PARSE_BLOCK_MAPPING_FIRST_KEY_STATE;
+                MAPPING_START_EVENT_INIT(*event, anchor, tag, implicit,
+                        YAML_BLOCK_MAPPING_STYLE, start_mark, end_mark);
+                return 1;
+            }
+            else if (anchor || tag) {
+                yaml_char_t *value = YAML_MALLOC(1);
+                if (!value) {
+                    parser->error = YAML_MEMORY_ERROR;
+                    goto error;
+                }
+                value[0] = '\0';
+                parser->state = POP(parser, parser->states);
+                SCALAR_EVENT_INIT(*event, anchor, tag, value, 0,
+                        implicit, 0, YAML_PLAIN_SCALAR_STYLE,
+                        start_mark, end_mark);
+                return 1;
+            }
+            else {
+                yaml_parser_set_parser_error_context(parser,
+                        (block ? "while parsing a block node"
+                         : "while parsing a flow node"), start_mark,
+                        "did not find expected node content", token->start_mark);
+                goto error;
+            }
+        }
+    }
+
+error:
+    yaml_free(anchor);
+    yaml_free(tag_handle);
+    yaml_free(tag_suffix);
+    yaml_free(tag);
+
+    return 0;
+}
+
+/*
+ * Parse the productions:
+ * block_sequence ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
+ *                    ********************  *********** *             *********
+ */
+
+static int
+yaml_parser_parse_block_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event, int first)
+{
+    yaml_token_t *token;
+
+    if (first) {
+        token = PEEK_TOKEN(parser);
+        if (!PUSH(parser, parser->marks, token->start_mark))
+            return 0;
+        SKIP_TOKEN(parser);
+    }
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_BLOCK_ENTRY_TOKEN)
+    {
+        yaml_mark_t mark = token->end_mark;
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_BLOCK_ENTRY_TOKEN &&
+                token->type != YAML_BLOCK_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_BLOCK_SEQUENCE_ENTRY_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 1, 0);
+        }
+        else {
+            parser->state = YAML_PARSE_BLOCK_SEQUENCE_ENTRY_STATE;
+            return yaml_parser_process_empty_scalar(parser, event, mark);
+        }
+    }
+
+    else if (token->type == YAML_BLOCK_END_TOKEN)
+    {
+        parser->state = POP(parser, parser->states);
+        (void)POP(parser, parser->marks);
+        SEQUENCE_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
+        SKIP_TOKEN(parser);
+        return 1;
+    }
+
+    else
+    {
+        return yaml_parser_set_parser_error_context(parser,
+                "while parsing a block collection", POP(parser, parser->marks),
+                "did not find expected '-' indicator", token->start_mark);
+    }
+}
+
+/*
+ * Parse the productions:
+ * indentless_sequence  ::= (BLOCK-ENTRY block_node?)+
+ *                           *********** *
+ */
+
+static int
+yaml_parser_parse_indentless_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_BLOCK_ENTRY_TOKEN)
+    {
+        yaml_mark_t mark = token->end_mark;
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_BLOCK_ENTRY_TOKEN &&
+                token->type != YAML_KEY_TOKEN &&
+                token->type != YAML_VALUE_TOKEN &&
+                token->type != YAML_BLOCK_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 1, 0);
+        }
+        else {
+            parser->state = YAML_PARSE_INDENTLESS_SEQUENCE_ENTRY_STATE;
+            return yaml_parser_process_empty_scalar(parser, event, mark);
+        }
+    }
+
+    else
+    {
+        parser->state = POP(parser, parser->states);
+        SEQUENCE_END_EVENT_INIT(*event, token->start_mark, token->start_mark);
+        return 1;
+    }
+}
+
+/*
+ * Parse the productions:
+ * block_mapping        ::= BLOCK-MAPPING_START
+ *                          *******************
+ *                          ((KEY block_node_or_indentless_sequence?)?
+ *                            *** *
+ *                          (VALUE block_node_or_indentless_sequence?)?)*
+ *
+ *                          BLOCK-END
+ *                          *********
+ */
+
+static int
+yaml_parser_parse_block_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event, int first)
+{
+    yaml_token_t *token;
+
+    if (first) {
+        token = PEEK_TOKEN(parser);
+        if (!PUSH(parser, parser->marks, token->start_mark))
+            return 0;
+        SKIP_TOKEN(parser);
+    }
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_KEY_TOKEN)
+    {
+        yaml_mark_t mark = token->end_mark;
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_KEY_TOKEN &&
+                token->type != YAML_VALUE_TOKEN &&
+                token->type != YAML_BLOCK_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_BLOCK_MAPPING_VALUE_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 1, 1);
+        }
+        else {
+            parser->state = YAML_PARSE_BLOCK_MAPPING_VALUE_STATE;
+            return yaml_parser_process_empty_scalar(parser, event, mark);
+        }
+    }
+
+    else if (token->type == YAML_BLOCK_END_TOKEN)
+    {
+        parser->state = POP(parser, parser->states);
+        (void)POP(parser, parser->marks);
+        MAPPING_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
+        SKIP_TOKEN(parser);
+        return 1;
+    }
+
+    else
+    {
+        return yaml_parser_set_parser_error_context(parser,
+                "while parsing a block mapping", POP(parser, parser->marks),
+                "did not find expected key", token->start_mark);
+    }
+}
+
+/*
+ * Parse the productions:
+ * block_mapping        ::= BLOCK-MAPPING_START
+ *
+ *                          ((KEY block_node_or_indentless_sequence?)?
+ *
+ *                          (VALUE block_node_or_indentless_sequence?)?)*
+ *                           ***** *
+ *                          BLOCK-END
+ *
+ */
+
+static int
+yaml_parser_parse_block_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_VALUE_TOKEN)
+    {
+        yaml_mark_t mark = token->end_mark;
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_KEY_TOKEN &&
+                token->type != YAML_VALUE_TOKEN &&
+                token->type != YAML_BLOCK_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_BLOCK_MAPPING_KEY_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 1, 1);
+        }
+        else {
+            parser->state = YAML_PARSE_BLOCK_MAPPING_KEY_STATE;
+            return yaml_parser_process_empty_scalar(parser, event, mark);
+        }
+    }
+
+    else
+    {
+        parser->state = YAML_PARSE_BLOCK_MAPPING_KEY_STATE;
+        return yaml_parser_process_empty_scalar(parser, event, token->start_mark);
+    }
+}
+
+/*
+ * Parse the productions:
+ * flow_sequence        ::= FLOW-SEQUENCE-START
+ *                          *******************
+ *                          (flow_sequence_entry FLOW-ENTRY)*
+ *                           *                   **********
+ *                          flow_sequence_entry?
+ *                          *
+ *                          FLOW-SEQUENCE-END
+ *                          *****************
+ * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+ *                          *
+ */
+
+static int
+yaml_parser_parse_flow_sequence_entry(yaml_parser_t *parser,
+        yaml_event_t *event, int first)
+{
+    yaml_token_t *token;
+
+    if (first) {
+        token = PEEK_TOKEN(parser);
+        if (!PUSH(parser, parser->marks, token->start_mark))
+            return 0;
+        SKIP_TOKEN(parser);
+    }
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type != YAML_FLOW_SEQUENCE_END_TOKEN)
+    {
+        if (!first) {
+            if (token->type == YAML_FLOW_ENTRY_TOKEN) {
+                SKIP_TOKEN(parser);
+                token = PEEK_TOKEN(parser);
+                if (!token) return 0;
+            }
+            else {
+                return yaml_parser_set_parser_error_context(parser,
+                        "while parsing a flow sequence", POP(parser, parser->marks),
+                        "did not find expected ',' or ']'", token->start_mark);
+            }
+        }
+
+        if (token->type == YAML_KEY_TOKEN) {
+            parser->state = YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_KEY_STATE;
+            MAPPING_START_EVENT_INIT(*event, NULL, NULL,
+                    1, YAML_FLOW_MAPPING_STYLE,
+                    token->start_mark, token->end_mark);
+            SKIP_TOKEN(parser);
+            return 1;
+        }
+
+        else if (token->type != YAML_FLOW_SEQUENCE_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_FLOW_SEQUENCE_ENTRY_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 0, 0);
+        }
+    }
+
+    parser->state = POP(parser, parser->states);
+    (void)POP(parser, parser->marks);
+    SEQUENCE_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
+    SKIP_TOKEN(parser);
+    return 1;
+}
+
+/*
+ * Parse the productions:
+ * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+ *                                      *** *
+ */
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type != YAML_VALUE_TOKEN && token->type != YAML_FLOW_ENTRY_TOKEN
+            && token->type != YAML_FLOW_SEQUENCE_END_TOKEN) {
+        if (!PUSH(parser, parser->states,
+                    YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE))
+            return 0;
+        return yaml_parser_parse_node(parser, event, 0, 0);
+    }
+    else {
+        yaml_mark_t mark = token->end_mark;
+        SKIP_TOKEN(parser);
+        parser->state = YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_VALUE_STATE;
+        return yaml_parser_process_empty_scalar(parser, event, mark);
+    }
+}
+
+/*
+ * Parse the productions:
+ * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+ *                                                      ***** *
+ */
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type == YAML_VALUE_TOKEN) {
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_FLOW_ENTRY_TOKEN
+                && token->type != YAML_FLOW_SEQUENCE_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 0, 0);
+        }
+    }
+    parser->state = YAML_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE;
+    return yaml_parser_process_empty_scalar(parser, event, token->start_mark);
+}
+
+/*
+ * Parse the productions:
+ * flow_sequence_entry  ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+ *                                                                      *
+ */
+
+static int
+yaml_parser_parse_flow_sequence_entry_mapping_end(yaml_parser_t *parser,
+        yaml_event_t *event)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    parser->state = YAML_PARSE_FLOW_SEQUENCE_ENTRY_STATE;
+
+    MAPPING_END_EVENT_INIT(*event, token->start_mark, token->start_mark);
+    return 1;
+}
+
+/*
+ * Parse the productions:
+ * flow_mapping         ::= FLOW-MAPPING-START
+ *                          ******************
+ *                          (flow_mapping_entry FLOW-ENTRY)*
+ *                           *                  **********
+ *                          flow_mapping_entry?
+ *                          ******************
+ *                          FLOW-MAPPING-END
+ *                          ****************
+ * flow_mapping_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+ *                          *           *** *
+ */
+
+static int
+yaml_parser_parse_flow_mapping_key(yaml_parser_t *parser,
+        yaml_event_t *event, int first)
+{
+    yaml_token_t *token;
+
+    if (first) {
+        token = PEEK_TOKEN(parser);
+        if (!PUSH(parser, parser->marks, token->start_mark))
+            return 0;
+        SKIP_TOKEN(parser);
+    }
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (token->type != YAML_FLOW_MAPPING_END_TOKEN)
+    {
+        if (!first) {
+            if (token->type == YAML_FLOW_ENTRY_TOKEN) {
+                SKIP_TOKEN(parser);
+                token = PEEK_TOKEN(parser);
+                if (!token) return 0;
+            }
+            else {
+                return yaml_parser_set_parser_error_context(parser,
+                        "while parsing a flow mapping", POP(parser, parser->marks),
+                        "did not find expected ',' or '}'", token->start_mark);
+            }
+        }
+
+        if (token->type == YAML_KEY_TOKEN) {
+            SKIP_TOKEN(parser);
+            token = PEEK_TOKEN(parser);
+            if (!token) return 0;
+            if (token->type != YAML_VALUE_TOKEN
+                    && token->type != YAML_FLOW_ENTRY_TOKEN
+                    && token->type != YAML_FLOW_MAPPING_END_TOKEN) {
+                if (!PUSH(parser, parser->states,
+                            YAML_PARSE_FLOW_MAPPING_VALUE_STATE))
+                    return 0;
+                return yaml_parser_parse_node(parser, event, 0, 0);
+            }
+            else {
+                parser->state = YAML_PARSE_FLOW_MAPPING_VALUE_STATE;
+                return yaml_parser_process_empty_scalar(parser, event,
+                        token->start_mark);
+            }
+        }
+        else if (token->type != YAML_FLOW_MAPPING_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_FLOW_MAPPING_EMPTY_VALUE_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 0, 0);
+        }
+    }
+
+    parser->state = POP(parser, parser->states);
+    (void)POP(parser, parser->marks);
+    MAPPING_END_EVENT_INIT(*event, token->start_mark, token->end_mark);
+    SKIP_TOKEN(parser);
+    return 1;
+}
+
+/*
+ * Parse the productions:
+ * flow_mapping_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+ *                                   *                  ***** *
+ */
+
+static int
+yaml_parser_parse_flow_mapping_value(yaml_parser_t *parser,
+        yaml_event_t *event, int empty)
+{
+    yaml_token_t *token;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) return 0;
+
+    if (empty) {
+        parser->state = YAML_PARSE_FLOW_MAPPING_KEY_STATE;
+        return yaml_parser_process_empty_scalar(parser, event,
+                token->start_mark);
+    }
+
+    if (token->type == YAML_VALUE_TOKEN) {
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) return 0;
+        if (token->type != YAML_FLOW_ENTRY_TOKEN
+                && token->type != YAML_FLOW_MAPPING_END_TOKEN) {
+            if (!PUSH(parser, parser->states,
+                        YAML_PARSE_FLOW_MAPPING_KEY_STATE))
+                return 0;
+            return yaml_parser_parse_node(parser, event, 0, 0);
+        }
+    }
+
+    parser->state = YAML_PARSE_FLOW_MAPPING_KEY_STATE;
+    return yaml_parser_process_empty_scalar(parser, event, token->start_mark);
+}
+
+/*
+ * Generate an empty scalar event.
+ */
+
+static int
+yaml_parser_process_empty_scalar(yaml_parser_t *parser, yaml_event_t *event,
+        yaml_mark_t mark)
+{
+    yaml_char_t *value;
+
+    value = YAML_MALLOC(1);
+    if (!value) {
+        parser->error = YAML_MEMORY_ERROR;
+        return 0;
+    }
+    value[0] = '\0';
+
+    SCALAR_EVENT_INIT(*event, NULL, NULL, value, 0,
+            1, 0, YAML_PLAIN_SCALAR_STYLE, mark, mark);
+
+    return 1;
+}
+
+/*
+ * Parse directives.
+ */
+
+static int
+yaml_parser_process_directives(yaml_parser_t *parser,
+        yaml_version_directive_t **version_directive_ref,
+        yaml_tag_directive_t **tag_directives_start_ref,
+        yaml_tag_directive_t **tag_directives_end_ref)
+{
+    yaml_tag_directive_t default_tag_directives[] = {
+        {(yaml_char_t *)"!", (yaml_char_t *)"!"},
+        {(yaml_char_t *)"!!", (yaml_char_t *)"tag:yaml.org,2002:"},
+        {NULL, NULL}
+    };
+    yaml_tag_directive_t *default_tag_directive;
+    yaml_version_directive_t *version_directive = NULL;
+    struct {
+        yaml_tag_directive_t *start;
+        yaml_tag_directive_t *end;
+        yaml_tag_directive_t *top;
+    } tag_directives = { NULL, NULL, NULL };
+    yaml_token_t *token;
+
+    if (!STACK_INIT(parser, tag_directives, yaml_tag_directive_t*))
+        goto error;
+
+    token = PEEK_TOKEN(parser);
+    if (!token) goto error;
+
+    while (token->type == YAML_VERSION_DIRECTIVE_TOKEN ||
+            token->type == YAML_TAG_DIRECTIVE_TOKEN)
+    {
+        if (token->type == YAML_VERSION_DIRECTIVE_TOKEN) {
+            if (version_directive) {
+                yaml_parser_set_parser_error(parser,
+                        "found duplicate %YAML directive", token->start_mark);
+                goto error;
+            }
+            if (token->data.version_directive.major != 1
+                    || (
+                        token->data.version_directive.minor != 1
+                        && token->data.version_directive.minor != 2
+                    )) {
+                yaml_parser_set_parser_error(parser,
+                        "found incompatible YAML document", token->start_mark);
+                goto error;
+            }
+            version_directive = YAML_MALLOC_STATIC(yaml_version_directive_t);
+            if (!version_directive) {
+                parser->error = YAML_MEMORY_ERROR;
+                goto error;
+            }
+            version_directive->major = token->data.version_directive.major;
+            version_directive->minor = token->data.version_directive.minor;
+        }
+
+        else if (token->type == YAML_TAG_DIRECTIVE_TOKEN) {
+            yaml_tag_directive_t value;
+            value.handle = token->data.tag_directive.handle;
+            value.prefix = token->data.tag_directive.prefix;
+
+            if (!yaml_parser_append_tag_directive(parser, value, 0,
+                        token->start_mark))
+                goto error;
+            if (!PUSH(parser, tag_directives, value))
+                goto error;
+        }
+
+        SKIP_TOKEN(parser);
+        token = PEEK_TOKEN(parser);
+        if (!token) goto error;
+    }
+
+    for (default_tag_directive = default_tag_directives;
+            default_tag_directive->handle; default_tag_directive++) {
+        if (!yaml_parser_append_tag_directive(parser, *default_tag_directive, 1,
+                    token->start_mark))
+            goto error;
+    }
+
+    if (version_directive_ref) {
+        *version_directive_ref = version_directive;
+    }
+    if (tag_directives_start_ref) {
+        if (STACK_EMPTY(parser, tag_directives)) {
+            *tag_directives_start_ref = *tag_directives_end_ref = NULL;
+            STACK_DEL(parser, tag_directives);
+        }
+        else {
+            *tag_directives_start_ref = tag_directives.start;
+            *tag_directives_end_ref = tag_directives.top;
+        }
+    }
+    else {
+        STACK_DEL(parser, tag_directives);
+    }
+
+    if (!version_directive_ref)
+        yaml_free(version_directive);
+    return 1;
+
+error:
+    yaml_free(version_directive);
+    while (!STACK_EMPTY(parser, tag_directives)) {
+        yaml_tag_directive_t tag_directive = POP(parser, tag_directives);
+        yaml_free(tag_directive.handle);
+        yaml_free(tag_directive.prefix);
+    }
+    STACK_DEL(parser, tag_directives);
+    return 0;
+}
+
+/*
+ * Append a tag directive to the directives stack.
+ */
+
+static int
+yaml_parser_append_tag_directive(yaml_parser_t *parser,
+        yaml_tag_directive_t value, int allow_duplicates, yaml_mark_t mark)
+{
+    yaml_tag_directive_t *tag_directive;
+    yaml_tag_directive_t copy = { NULL, NULL };
+
+    for (tag_directive = parser->tag_directives.start;
+            tag_directive != parser->tag_directives.top; tag_directive ++) {
+        if (strcmp((char *)value.handle, (char *)tag_directive->handle) == 0) {
+            if (allow_duplicates)
+                return 1;
+            return yaml_parser_set_parser_error(parser,
+                    "found duplicate %TAG directive", mark);
+        }
+    }
+
+    copy.handle = yaml_strdup(value.handle);
+    copy.prefix = yaml_strdup(value.prefix);
+    if (!copy.handle || !copy.prefix) {
+        parser->error = YAML_MEMORY_ERROR;
+        goto error;
+    }
+
+    if (!PUSH(parser, parser->tag_directives, copy))
+        goto error;
+
+    return 1;
+
+error:
+    yaml_free(copy.handle);
+    yaml_free(copy.prefix);
+    return 0;
+}
+
diff --git a/contrib/libs/yaml/src/reader.c b/contrib/libs/yaml/src/reader.c
new file mode 100644
index 0000000000..f3ac54c251
--- /dev/null
+++ b/contrib/libs/yaml/src/reader.c
@@ -0,0 +1,469 @@
+
+#include "yaml_private.h"
+
+/*
+ * Declarations.
+ */
+
+static int
+yaml_parser_set_reader_error(yaml_parser_t *parser, const char *problem,
+        size_t offset, int value);
+
+static int
+yaml_parser_update_raw_buffer(yaml_parser_t *parser);
+
+static int
+yaml_parser_determine_encoding(yaml_parser_t *parser);
+
+YAML_DECLARE(int)
+yaml_parser_update_buffer(yaml_parser_t *parser, size_t length);
+
+/*
+ * Set the reader error and return 0.
+ */
+
+static int
+yaml_parser_set_reader_error(yaml_parser_t *parser, const char *problem,
+        size_t offset, int value)
+{
+    parser->error = YAML_READER_ERROR;
+    parser->problem = problem;
+    parser->problem_offset = offset;
+    parser->problem_value = value;
+
+    return 0;
+}
+
+/*
+ * Byte order marks.
+ */
+
+#define BOM_UTF8    "\xef\xbb\xbf"
+#define BOM_UTF16LE "\xff\xfe"
+#define BOM_UTF16BE "\xfe\xff"
+
+/*
+ * Determine the input stream encoding by checking the BOM symbol. If no BOM is
+ * found, the UTF-8 encoding is assumed. Return 1 on success, 0 on failure.
+ */
+
+static int
+yaml_parser_determine_encoding(yaml_parser_t *parser)
+{
+    /* Ensure that we had enough bytes in the raw buffer. */
+
+    while (!parser->eof
+            && parser->raw_buffer.last - parser->raw_buffer.pointer < 3) {
+        if (!yaml_parser_update_raw_buffer(parser)) {
+            return 0;
+        }
+    }
+
+    /* Determine the encoding. */
+
+    if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 2
+            && !memcmp(parser->raw_buffer.pointer, BOM_UTF16LE, 2)) {
+        parser->encoding = YAML_UTF16LE_ENCODING;
+        parser->raw_buffer.pointer += 2;
+        parser->offset += 2;
+    }
+    else if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 2
+            && !memcmp(parser->raw_buffer.pointer, BOM_UTF16BE, 2)) {
+        parser->encoding = YAML_UTF16BE_ENCODING;
+        parser->raw_buffer.pointer += 2;
+        parser->offset += 2;
+    }
+    else if (parser->raw_buffer.last - parser->raw_buffer.pointer >= 3
+            && !memcmp(parser->raw_buffer.pointer, BOM_UTF8, 3)) {
+        parser->encoding = YAML_UTF8_ENCODING;
+        parser->raw_buffer.pointer += 3;
+        parser->offset += 3;
+    }
+    else {
+        parser->encoding = YAML_UTF8_ENCODING;
+    }
+
+    return 1;
+}
+
+/*
+ * Update the raw buffer.
+ */
+
+static int
+yaml_parser_update_raw_buffer(yaml_parser_t *parser)
+{
+    size_t size_read = 0;
+
+    /* Return if the raw buffer is full. */
+
+    if (parser->raw_buffer.start == parser->raw_buffer.pointer
+            && parser->raw_buffer.last == parser->raw_buffer.end)
+        return 1;
+
+    /* Return on EOF. */
+
+    if (parser->eof) return 1;
+
+    /* Move the remaining bytes in the raw buffer to the beginning. */
+
+    if (parser->raw_buffer.start < parser->raw_buffer.pointer
+            && parser->raw_buffer.pointer < parser->raw_buffer.last) {
+        memmove(parser->raw_buffer.start, parser->raw_buffer.pointer,
+                parser->raw_buffer.last - parser->raw_buffer.pointer);
+    }
+    parser->raw_buffer.last -=
+        parser->raw_buffer.pointer - parser->raw_buffer.start;
+    parser->raw_buffer.pointer = parser->raw_buffer.start;
+
+    /* Call the read handler to fill the buffer. */
+
+    if (!parser->read_handler(parser->read_handler_data, parser->raw_buffer.last,
+                parser->raw_buffer.end - parser->raw_buffer.last, &size_read)) {
+        return yaml_parser_set_reader_error(parser, "input error",
+                parser->offset, -1);
+    }
+    parser->raw_buffer.last += size_read;
+    if (!size_read) {
+        parser->eof = 1;
+    }
+
+    return 1;
+}
+
+/*
+ * Ensure that the buffer contains at least `length` characters.
+ * Return 1 on success, 0 on failure.
+ *
+ * The length is supposed to be significantly less that the buffer size.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_update_buffer(yaml_parser_t *parser, size_t length)
+{
+    int first = 1;
+
+    assert(parser->read_handler);   /* Read handler must be set. */
+
+    /* If the EOF flag is set and the raw buffer is empty, do nothing. */
+
+    if (parser->eof && parser->raw_buffer.pointer == parser->raw_buffer.last)
+        return 1;
+
+    /* Return if the buffer contains enough characters. */
+
+    if (parser->unread >= length)
+        return 1;
+
+    /* Determine the input encoding if it is not known yet. */
+
+    if (!parser->encoding) {
+        if (!yaml_parser_determine_encoding(parser))
+            return 0;
+    }
+
+    /* Move the unread characters to the beginning of the buffer. */
+
+    if (parser->buffer.start < parser->buffer.pointer
+            && parser->buffer.pointer < parser->buffer.last) {
+        size_t size = parser->buffer.last - parser->buffer.pointer;
+        memmove(parser->buffer.start, parser->buffer.pointer, size);
+        parser->buffer.pointer = parser->buffer.start;
+        parser->buffer.last = parser->buffer.start + size;
+    }
+    else if (parser->buffer.pointer == parser->buffer.last) {
+        parser->buffer.pointer = parser->buffer.start;
+        parser->buffer.last = parser->buffer.start;
+    }
+
+    /* Fill the buffer until it has enough characters. */
+
+    while (parser->unread < length)
+    {
+        /* Fill the raw buffer if necessary. */
+
+        if (!first || parser->raw_buffer.pointer == parser->raw_buffer.last) {
+            if (!yaml_parser_update_raw_buffer(parser)) return 0;
+        }
+        first = 0;
+
+        /* Decode the raw buffer. */
+
+        while (parser->raw_buffer.pointer != parser->raw_buffer.last)
+        {
+            unsigned int value = 0, value2 = 0;
+            int incomplete = 0;
+            unsigned char octet;
+            unsigned int width = 0;
+            int low, high;
+            size_t k;
+            size_t raw_unread = parser->raw_buffer.last - parser->raw_buffer.pointer;
+
+            /* Decode the next character. */
+
+            switch (parser->encoding)
+            {
+                case YAML_UTF8_ENCODING:
+
+                    /*
+                     * Decode a UTF-8 character.  Check RFC 3629
+                     * (http://www.ietf.org/rfc/rfc3629.txt) for more details.
+                     *
+                     * The following table (taken from the RFC) is used for
+                     * decoding.
+                     *
+                     *    Char. number range |        UTF-8 octet sequence
+                     *      (hexadecimal)    |              (binary)
+                     *   --------------------+------------------------------------
+                     *   0000 0000-0000 007F | 0xxxxxxx
+                     *   0000 0080-0000 07FF | 110xxxxx 10xxxxxx
+                     *   0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
+                     *   0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+                     *
+                     * Additionally, the characters in the range 0xD800-0xDFFF
+                     * are prohibited as they are reserved for use with UTF-16
+                     * surrogate pairs.
+                     */
+
+                    /* Determine the length of the UTF-8 sequence. */
+
+                    octet = parser->raw_buffer.pointer[0];
+                    width = (octet & 0x80) == 0x00 ? 1 :
+                            (octet & 0xE0) == 0xC0 ? 2 :
+                            (octet & 0xF0) == 0xE0 ? 3 :
+                            (octet & 0xF8) == 0xF0 ? 4 : 0;
+
+                    /* Check if the leading octet is valid. */
+
+                    if (!width)
+                        return yaml_parser_set_reader_error(parser,
+                                "invalid leading UTF-8 octet",
+                                parser->offset, octet);
+
+                    /* Check if the raw buffer contains an incomplete character. */
+
+                    if (width > raw_unread) {
+                        if (parser->eof) {
+                            return yaml_parser_set_reader_error(parser,
+                                    "incomplete UTF-8 octet sequence",
+                                    parser->offset, -1);
+                        }
+                        incomplete = 1;
+                        break;
+                    }
+
+                    /* Decode the leading octet. */
+
+                    value = (octet & 0x80) == 0x00 ? octet & 0x7F :
+                            (octet & 0xE0) == 0xC0 ? octet & 0x1F :
+                            (octet & 0xF0) == 0xE0 ? octet & 0x0F :
+                            (octet & 0xF8) == 0xF0 ? octet & 0x07 : 0;
+
+                    /* Check and decode the trailing octets. */
+
+                    for (k = 1; k < width; k ++)
+                    {
+                        octet = parser->raw_buffer.pointer[k];
+
+                        /* Check if the octet is valid. */
+
+                        if ((octet & 0xC0) != 0x80)
+                            return yaml_parser_set_reader_error(parser,
+                                    "invalid trailing UTF-8 octet",
+                                    parser->offset+k, octet);
+
+                        /* Decode the octet. */
+
+                        value = (value << 6) + (octet & 0x3F);
+                    }
+
+                    /* Check the length of the sequence against the value. */
+
+                    if (!((width == 1) ||
+                            (width == 2 && value >= 0x80) ||
+                            (width == 3 && value >= 0x800) ||
+                            (width == 4 && value >= 0x10000)))
+                        return yaml_parser_set_reader_error(parser,
+                                "invalid length of a UTF-8 sequence",
+                                parser->offset, -1);
+
+                    /* Check the range of the value. */
+
+                    if ((value >= 0xD800 && value <= 0xDFFF) || value > 0x10FFFF)
+                        return yaml_parser_set_reader_error(parser,
+                                "invalid Unicode character",
+                                parser->offset, value);
+
+                    break;
+
+                case YAML_UTF16LE_ENCODING:
+                case YAML_UTF16BE_ENCODING:
+
+                    low = (parser->encoding == YAML_UTF16LE_ENCODING ? 0 : 1);
+                    high = (parser->encoding == YAML_UTF16LE_ENCODING ? 1 : 0);
+
+                    /*
+                     * The UTF-16 encoding is not as simple as one might
+                     * naively think.  Check RFC 2781
+                     * (http://www.ietf.org/rfc/rfc2781.txt).
+                     *
+                     * Normally, two subsequent bytes describe a Unicode
+                     * character.  However a special technique (called a
+                     * surrogate pair) is used for specifying character
+                     * values larger than 0xFFFF.
+                     *
+                     * A surrogate pair consists of two pseudo-characters:
+                     *      high surrogate area (0xD800-0xDBFF)
+                     *      low surrogate area (0xDC00-0xDFFF)
+                     *
+                     * The following formulas are used for decoding
+                     * and encoding characters using surrogate pairs:
+                     *
+                     *  U  = U' + 0x10000   (0x01 00 00 <= U <= 0x10 FF FF)
+                     *  U' = yyyyyyyyyyxxxxxxxxxx   (0 <= U' <= 0x0F FF FF)
+                     *  W1 = 110110yyyyyyyyyy
+                     *  W2 = 110111xxxxxxxxxx
+                     *
+                     * where U is the character value, W1 is the high surrogate
+                     * area, W2 is the low surrogate area.
+                     */
+
+                    /* Check for incomplete UTF-16 character. */
+
+                    if (raw_unread < 2) {
+                        if (parser->eof) {
+                            return yaml_parser_set_reader_error(parser,
+                                    "incomplete UTF-16 character",
+                                    parser->offset, -1);
+                        }
+                        incomplete = 1;
+                        break;
+                    }
+
+                    /* Get the character. */
+
+                    value = parser->raw_buffer.pointer[low]
+                        + (parser->raw_buffer.pointer[high] << 8);
+
+                    /* Check for unexpected low surrogate area. */
+
+                    if ((value & 0xFC00) == 0xDC00)
+                        return yaml_parser_set_reader_error(parser,
+                                "unexpected low surrogate area",
+                                parser->offset, value);
+
+                    /* Check for a high surrogate area. */
+
+                    if ((value & 0xFC00) == 0xD800) {
+
+                        width = 4;
+
+                        /* Check for incomplete surrogate pair. */
+
+                        if (raw_unread < 4) {
+                            if (parser->eof) {
+                                return yaml_parser_set_reader_error(parser,
+                                        "incomplete UTF-16 surrogate pair",
+                                        parser->offset, -1);
+                            }
+                            incomplete = 1;
+                            break;
+                        }
+
+                        /* Get the next character. */
+
+                        value2 = parser->raw_buffer.pointer[low+2]
+                            + (parser->raw_buffer.pointer[high+2] << 8);
+
+                        /* Check for a low surrogate area. */
+
+                        if ((value2 & 0xFC00) != 0xDC00)
+                            return yaml_parser_set_reader_error(parser,
+                                    "expected low surrogate area",
+                                    parser->offset+2, value2);
+
+                        /* Generate the value of the surrogate pair. */
+
+                        value = 0x10000 + ((value & 0x3FF) << 10) + (value2 & 0x3FF);
+                    }
+
+                    else {
+                        width = 2;
+                    }
+
+                    break;
+
+                default:
+                    assert(1);      /* Impossible. */
+            }
+
+            /* Check if the raw buffer contains enough bytes to form a character. */
+
+            if (incomplete) break;
+
+            /*
+             * Check if the character is in the allowed range:
+             *      #x9 | #xA | #xD | [#x20-#x7E]               (8 bit)
+             *      | #x85 | [#xA0-#xD7FF] | [#xE000-#xFFFD]    (16 bit)
+             *      | [#x10000-#x10FFFF]                        (32 bit)
+             */
+
+            if (! (value == 0x09 || value == 0x0A || value == 0x0D
+                        || (value >= 0x20 && value <= 0x7E)
+                        || (value == 0x85) || (value >= 0xA0 && value <= 0xD7FF)
+                        || (value >= 0xE000 && value <= 0xFFFD)
+                        || (value >= 0x10000 && value <= 0x10FFFF)))
+                return yaml_parser_set_reader_error(parser,
+                        "control characters are not allowed",
+                        parser->offset, value);
+
+            /* Move the raw pointers. */
+
+            parser->raw_buffer.pointer += width;
+            parser->offset += width;
+
+            /* Finally put the character into the buffer. */
+
+            /* 0000 0000-0000 007F -> 0xxxxxxx */
+            if (value <= 0x7F) {
+                *(parser->buffer.last++) = value;
+            }
+            /* 0000 0080-0000 07FF -> 110xxxxx 10xxxxxx */
+            else if (value <= 0x7FF) {
+                *(parser->buffer.last++) = 0xC0 + (value >> 6);
+                *(parser->buffer.last++) = 0x80 + (value & 0x3F);
+            }
+            /* 0000 0800-0000 FFFF -> 1110xxxx 10xxxxxx 10xxxxxx */
+            else if (value <= 0xFFFF) {
+                *(parser->buffer.last++) = 0xE0 + (value >> 12);
+                *(parser->buffer.last++) = 0x80 + ((value >> 6) & 0x3F);
+                *(parser->buffer.last++) = 0x80 + (value & 0x3F);
+            }
+            /* 0001 0000-0010 FFFF -> 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */
+            else {
+                *(parser->buffer.last++) = 0xF0 + (value >> 18);
+                *(parser->buffer.last++) = 0x80 + ((value >> 12) & 0x3F);
+                *(parser->buffer.last++) = 0x80 + ((value >> 6) & 0x3F);
+                *(parser->buffer.last++) = 0x80 + (value & 0x3F);
+            }
+
+            parser->unread ++;
+        }
+
+        /* On EOF, put NUL into the buffer and return. */
+
+        if (parser->eof) {
+            *(parser->buffer.last++) = '\0';
+            parser->unread ++;
+            return 1;
+        }
+
+    }
+
+    if (parser->offset >= MAX_FILE_SIZE) {
+        return yaml_parser_set_reader_error(parser, "input is too long",
+            parser->offset, -1);
+    }
+
+    return 1;
+}
diff --git a/contrib/libs/yaml/src/scanner.c b/contrib/libs/yaml/src/scanner.c
new file mode 100644
index 0000000000..c6b4987656
--- /dev/null
+++ b/contrib/libs/yaml/src/scanner.c
@@ -0,0 +1,3598 @@
+
+/*
+ * Introduction
+ * ************
+ *
+ * The following notes assume that you are familiar with the YAML specification
+ * (http://yaml.org/spec/cvs/current.html).  We mostly follow it, although in
+ * some cases we are less restrictive that it requires.
+ *
+ * The process of transforming a YAML stream into a sequence of events is
+ * divided on two steps: Scanning and Parsing.
+ *
+ * The Scanner transforms the input stream into a sequence of tokens, while the
+ * parser transform the sequence of tokens produced by the Scanner into a
+ * sequence of parsing events.
+ *
+ * The Scanner is rather clever and complicated. The Parser, on the contrary,
+ * is a straightforward implementation of a recursive-descendant parser (or,
+ * LL(1) parser, as it is usually called).
+ *
+ * Actually there are two issues of Scanning that might be called "clever", the
+ * rest is quite straightforward.  The issues are "block collection start" and
+ * "simple keys".  Both issues are explained below in details.
+ *
+ * Here the Scanning step is explained and implemented.  We start with the list
+ * of all the tokens produced by the Scanner together with short descriptions.
+ *
+ * Now, tokens:
+ *
+ *      STREAM-START(encoding)          # The stream start.
+ *      STREAM-END                      # The stream end.
+ *      VERSION-DIRECTIVE(major,minor)  # The '%YAML' directive.
+ *      TAG-DIRECTIVE(handle,prefix)    # The '%TAG' directive.
+ *      DOCUMENT-START                  # '---'
+ *      DOCUMENT-END                    # '...'
+ *      BLOCK-SEQUENCE-START            # Indentation increase denoting a block
+ *      BLOCK-MAPPING-START             # sequence or a block mapping.
+ *      BLOCK-END                       # Indentation decrease.
+ *      FLOW-SEQUENCE-START             # '['
+ *      FLOW-SEQUENCE-END               # ']'
+ *      FLOW-MAPPING-START              # '{'
+ *      FLOW-MAPPING-END                # '}'
+ *      BLOCK-ENTRY                     # '-'
+ *      FLOW-ENTRY                      # ','
+ *      KEY                             # '?' or nothing (simple keys).
+ *      VALUE                           # ':'
+ *      ALIAS(anchor)                   # '*anchor'
+ *      ANCHOR(anchor)                  # '&anchor'
+ *      TAG(handle,suffix)              # '!handle!suffix'
+ *      SCALAR(value,style)             # A scalar.
+ *
+ * The following two tokens are "virtual" tokens denoting the beginning and the
+ * end of the stream:
+ *
+ *      STREAM-START(encoding)
+ *      STREAM-END
+ *
+ * We pass the information about the input stream encoding with the
+ * STREAM-START token.
+ *
+ * The next two tokens are responsible for tags:
+ *
+ *      VERSION-DIRECTIVE(major,minor)
+ *      TAG-DIRECTIVE(handle,prefix)
+ *
+ * Example:
+ *
+ *      %YAML   1.1
+ *      %TAG    !   !foo
+ *      %TAG    !yaml!  tag:yaml.org,2002:
+ *      ---
+ *
+ * The corresponding sequence of tokens:
+ *
+ *      STREAM-START(utf-8)
+ *      VERSION-DIRECTIVE(1,1)
+ *      TAG-DIRECTIVE("!","!foo")
+ *      TAG-DIRECTIVE("!yaml","tag:yaml.org,2002:")
+ *      DOCUMENT-START
+ *      STREAM-END
+ *
+ * Note that the VERSION-DIRECTIVE and TAG-DIRECTIVE tokens occupy a whole
+ * line.
+ *
+ * The document start and end indicators are represented by:
+ *
+ *      DOCUMENT-START
+ *      DOCUMENT-END
+ *
+ * Note that if a YAML stream contains an implicit document (without '---'
+ * and '...' indicators), no DOCUMENT-START and DOCUMENT-END tokens will be
+ * produced.
+ *
+ * In the following examples, we present whole documents together with the
+ * produced tokens.
+ *
+ *      1. An implicit document:
+ *
+ *          'a scalar'
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          SCALAR("a scalar",single-quoted)
+ *          STREAM-END
+ *
+ *      2. An explicit document:
+ *
+ *          ---
+ *          'a scalar'
+ *          ...
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          DOCUMENT-START
+ *          SCALAR("a scalar",single-quoted)
+ *          DOCUMENT-END
+ *          STREAM-END
+ *
+ *      3. Several documents in a stream:
+ *
+ *          'a scalar'
+ *          ---
+ *          'another scalar'
+ *          ---
+ *          'yet another scalar'
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          SCALAR("a scalar",single-quoted)
+ *          DOCUMENT-START
+ *          SCALAR("another scalar",single-quoted)
+ *          DOCUMENT-START
+ *          SCALAR("yet another scalar",single-quoted)
+ *          STREAM-END
+ *
+ * We have already introduced the SCALAR token above.  The following tokens are
+ * used to describe aliases, anchors, tag, and scalars:
+ *
+ *      ALIAS(anchor)
+ *      ANCHOR(anchor)
+ *      TAG(handle,suffix)
+ *      SCALAR(value,style)
+ *
+ * The following series of examples illustrate the usage of these tokens:
+ *
+ *      1. A recursive sequence:
+ *
+ *          &A [ *A ]
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          ANCHOR("A")
+ *          FLOW-SEQUENCE-START
+ *          ALIAS("A")
+ *          FLOW-SEQUENCE-END
+ *          STREAM-END
+ *
+ *      2. A tagged scalar:
+ *
+ *          !!float "3.14"  # A good approximation.
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          TAG("!!","float")
+ *          SCALAR("3.14",double-quoted)
+ *          STREAM-END
+ *
+ *      3. Various scalar styles:
+ *
+ *          --- # Implicit empty plain scalars do not produce tokens.
+ *          --- a plain scalar
+ *          --- 'a single-quoted scalar'
+ *          --- "a double-quoted scalar"
+ *          --- |-
+ *            a literal scalar
+ *          --- >-
+ *            a folded
+ *            scalar
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          DOCUMENT-START
+ *          DOCUMENT-START
+ *          SCALAR("a plain scalar",plain)
+ *          DOCUMENT-START
+ *          SCALAR("a single-quoted scalar",single-quoted)
+ *          DOCUMENT-START
+ *          SCALAR("a double-quoted scalar",double-quoted)
+ *          DOCUMENT-START
+ *          SCALAR("a literal scalar",literal)
+ *          DOCUMENT-START
+ *          SCALAR("a folded scalar",folded)
+ *          STREAM-END
+ *
+ * Now it's time to review collection-related tokens. We will start with
+ * flow collections:
+ *
+ *      FLOW-SEQUENCE-START
+ *      FLOW-SEQUENCE-END
+ *      FLOW-MAPPING-START
+ *      FLOW-MAPPING-END
+ *      FLOW-ENTRY
+ *      KEY
+ *      VALUE
+ *
+ * The tokens FLOW-SEQUENCE-START, FLOW-SEQUENCE-END, FLOW-MAPPING-START, and
+ * FLOW-MAPPING-END represent the indicators '[', ']', '{', and '}'
+ * correspondingly.  FLOW-ENTRY represent the ',' indicator.  Finally the
+ * indicators '?' and ':', which are used for denoting mapping keys and values,
+ * are represented by the KEY and VALUE tokens.
+ *
+ * The following examples show flow collections:
+ *
+ *      1. A flow sequence:
+ *
+ *          [item 1, item 2, item 3]
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          FLOW-SEQUENCE-START
+ *          SCALAR("item 1",plain)
+ *          FLOW-ENTRY
+ *          SCALAR("item 2",plain)
+ *          FLOW-ENTRY
+ *          SCALAR("item 3",plain)
+ *          FLOW-SEQUENCE-END
+ *          STREAM-END
+ *
+ *      2. A flow mapping:
+ *
+ *          {
+ *              a simple key: a value,  # Note that the KEY token is produced.
+ *              ? a complex key: another value,
+ *          }
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          FLOW-MAPPING-START
+ *          KEY
+ *          SCALAR("a simple key",plain)
+ *          VALUE
+ *          SCALAR("a value",plain)
+ *          FLOW-ENTRY
+ *          KEY
+ *          SCALAR("a complex key",plain)
+ *          VALUE
+ *          SCALAR("another value",plain)
+ *          FLOW-ENTRY
+ *          FLOW-MAPPING-END
+ *          STREAM-END
+ *
+ * A simple key is a key which is not denoted by the '?' indicator.  Note that
+ * the Scanner still produce the KEY token whenever it encounters a simple key.
+ *
+ * For scanning block collections, the following tokens are used (note that we
+ * repeat KEY and VALUE here):
+ *
+ *      BLOCK-SEQUENCE-START
+ *      BLOCK-MAPPING-START
+ *      BLOCK-END
+ *      BLOCK-ENTRY
+ *      KEY
+ *      VALUE
+ *
+ * The tokens BLOCK-SEQUENCE-START and BLOCK-MAPPING-START denote indentation
+ * increase that precedes a block collection (cf. the INDENT token in Python).
+ * The token BLOCK-END denote indentation decrease that ends a block collection
+ * (cf. the DEDENT token in Python).  However YAML has some syntax pecularities
+ * that makes detections of these tokens more complex.
+ *
+ * The tokens BLOCK-ENTRY, KEY, and VALUE are used to represent the indicators
+ * '-', '?', and ':' correspondingly.
+ *
+ * The following examples show how the tokens BLOCK-SEQUENCE-START,
+ * BLOCK-MAPPING-START, and BLOCK-END are emitted by the Scanner:
+ *
+ *      1. Block sequences:
+ *
+ *          - item 1
+ *          - item 2
+ *          -
+ *            - item 3.1
+ *            - item 3.2
+ *          -
+ *            key 1: value 1
+ *            key 2: value 2
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          BLOCK-SEQUENCE-START
+ *          BLOCK-ENTRY
+ *          SCALAR("item 1",plain)
+ *          BLOCK-ENTRY
+ *          SCALAR("item 2",plain)
+ *          BLOCK-ENTRY
+ *          BLOCK-SEQUENCE-START
+ *          BLOCK-ENTRY
+ *          SCALAR("item 3.1",plain)
+ *          BLOCK-ENTRY
+ *          SCALAR("item 3.2",plain)
+ *          BLOCK-END
+ *          BLOCK-ENTRY
+ *          BLOCK-MAPPING-START
+ *          KEY
+ *          SCALAR("key 1",plain)
+ *          VALUE
+ *          SCALAR("value 1",plain)
+ *          KEY
+ *          SCALAR("key 2",plain)
+ *          VALUE
+ *          SCALAR("value 2",plain)
+ *          BLOCK-END
+ *          BLOCK-END
+ *          STREAM-END
+ *
+ *      2. Block mappings:
+ *
+ *          a simple key: a value   # The KEY token is produced here.
+ *          ? a complex key
+ *          : another value
+ *          a mapping:
+ *            key 1: value 1
+ *            key 2: value 2
+ *          a sequence:
+ *            - item 1
+ *            - item 2
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          BLOCK-MAPPING-START
+ *          KEY
+ *          SCALAR("a simple key",plain)
+ *          VALUE
+ *          SCALAR("a value",plain)
+ *          KEY
+ *          SCALAR("a complex key",plain)
+ *          VALUE
+ *          SCALAR("another value",plain)
+ *          KEY
+ *          SCALAR("a mapping",plain)
+ *          VALUE
+ *          BLOCK-MAPPING-START
+ *          KEY
+ *          SCALAR("key 1",plain)
+ *          VALUE
+ *          SCALAR("value 1",plain)
+ *          KEY
+ *          SCALAR("key 2",plain)
+ *          VALUE
+ *          SCALAR("value 2",plain)
+ *          BLOCK-END
+ *          KEY
+ *          SCALAR("a sequence",plain)
+ *          VALUE
+ *          BLOCK-SEQUENCE-START
+ *          BLOCK-ENTRY
+ *          SCALAR("item 1",plain)
+ *          BLOCK-ENTRY
+ *          SCALAR("item 2",plain)
+ *          BLOCK-END
+ *          BLOCK-END
+ *          STREAM-END
+ *
+ * YAML does not always require to start a new block collection from a new
+ * line.  If the current line contains only '-', '?', and ':' indicators, a new
+ * block collection may start at the current line.  The following examples
+ * illustrate this case:
+ *
+ *      1. Collections in a sequence:
+ *
+ *          - - item 1
+ *            - item 2
+ *          - key 1: value 1
+ *            key 2: value 2
+ *          - ? complex key
+ *            : complex value
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          BLOCK-SEQUENCE-START
+ *          BLOCK-ENTRY
+ *          BLOCK-SEQUENCE-START
+ *          BLOCK-ENTRY
+ *          SCALAR("item 1",plain)
+ *          BLOCK-ENTRY
+ *          SCALAR("item 2",plain)
+ *          BLOCK-END
+ *          BLOCK-ENTRY
+ *          BLOCK-MAPPING-START
+ *          KEY
+ *          SCALAR("key 1",plain)
+ *          VALUE
+ *          SCALAR("value 1",plain)
+ *          KEY
+ *          SCALAR("key 2",plain)
+ *          VALUE
+ *          SCALAR("value 2",plain)
+ *          BLOCK-END
+ *          BLOCK-ENTRY
+ *          BLOCK-MAPPING-START
+ *          KEY
+ *          SCALAR("complex key")
+ *          VALUE
+ *          SCALAR("complex value")
+ *          BLOCK-END
+ *          BLOCK-END
+ *          STREAM-END
+ *
+ *      2. Collections in a mapping:
+ *
+ *          ? a sequence
+ *          : - item 1
+ *            - item 2
+ *          ? a mapping
+ *          : key 1: value 1
+ *            key 2: value 2
+ *
+ *      Tokens:
+ *
+ *          STREAM-START(utf-8)
+ *          BLOCK-MAPPING-START
+ *          KEY
+ *          SCALAR("a sequence",plain)
+ *          VALUE
+ *          BLOCK-SEQUENCE-START
+ *          BLOCK-ENTRY
+ *          SCALAR("item 1",plain)
+ *          BLOCK-ENTRY
+ *          SCALAR("item 2",plain)
+ *          BLOCK-END
+ *          KEY
+ *          SCALAR("a mapping",plain)
+ *          VALUE
+ *          BLOCK-MAPPING-START
+ *          KEY
+ *          SCALAR("key 1",plain)
+ *          VALUE
+ *          SCALAR("value 1",plain)
+ *          KEY
+ *          SCALAR("key 2",plain)
+ *          VALUE
+ *          SCALAR("value 2",plain)
+ *          BLOCK-END
+ *          BLOCK-END
+ *          STREAM-END
+ *
+ * YAML also permits non-indented sequences if they are included into a block
+ * mapping.  In this case, the token BLOCK-SEQUENCE-START is not produced:
+ *
+ *      key:
+ *      - item 1    # BLOCK-SEQUENCE-START is NOT produced here.
+ *      - item 2
+ *
+ * Tokens:
+ *
+ *      STREAM-START(utf-8)
+ *      BLOCK-MAPPING-START
+ *      KEY
+ *      SCALAR("key",plain)
+ *      VALUE
+ *      BLOCK-ENTRY
+ *      SCALAR("item 1",plain)
+ *      BLOCK-ENTRY
+ *      SCALAR("item 2",plain)
+ *      BLOCK-END
+ */
+
+#include "yaml_private.h"
+
+/*
+ * Ensure that the buffer contains the required number of characters.
+ * Return 1 on success, 0 on failure (reader error or memory error).
+ */
+
+#define CACHE(parser,length)                                                    \
+    (parser->unread >= (length)                                                 \
+        ? 1                                                                     \
+        : yaml_parser_update_buffer(parser, (length)))
+
+/*
+ * Advance the buffer pointer.
+ */
+
+#define SKIP(parser)                                                            \
+     (parser->mark.index ++,                                                    \
+      parser->mark.column ++,                                                   \
+      parser->unread --,                                                        \
+      parser->buffer.pointer += WIDTH(parser->buffer))
+
+#define SKIP_LINE(parser)                                                       \
+     (IS_CRLF(parser->buffer) ?                                                 \
+      (parser->mark.index += 2,                                                 \
+       parser->mark.column = 0,                                                 \
+       parser->mark.line ++,                                                    \
+       parser->unread -= 2,                                                     \
+       parser->buffer.pointer += 2) :                                           \
+      IS_BREAK(parser->buffer) ?                                                \
+      (parser->mark.index ++,                                                   \
+       parser->mark.column = 0,                                                 \
+       parser->mark.line ++,                                                    \
+       parser->unread --,                                                       \
+       parser->buffer.pointer += WIDTH(parser->buffer)) : 0)
+
+/*
+ * Copy a character to a string buffer and advance pointers.
+ */
+
+#define READ(parser,string)                                                     \
+     (STRING_EXTEND(parser,string) ?                                            \
+         (COPY(string,parser->buffer),                                          \
+          parser->mark.index ++,                                                \
+          parser->mark.column ++,                                               \
+          parser->unread --,                                                    \
+          1) : 0)
+
+/*
+ * Copy a line break character to a string buffer and advance pointers.
+ */
+
+#define READ_LINE(parser,string)                                                \
+    (STRING_EXTEND(parser,string) ?                                             \
+    (((CHECK_AT(parser->buffer,'\r',0)                                          \
+       && CHECK_AT(parser->buffer,'\n',1)) ?        /* CR LF -> LF */           \
+     (*((string).pointer++) = (yaml_char_t) '\n',                               \
+      parser->buffer.pointer += 2,                                              \
+      parser->mark.index += 2,                                                  \
+      parser->mark.column = 0,                                                  \
+      parser->mark.line ++,                                                     \
+      parser->unread -= 2) :                                                    \
+     (CHECK_AT(parser->buffer,'\r',0)                                           \
+      || CHECK_AT(parser->buffer,'\n',0)) ?         /* CR|LF -> LF */           \
+     (*((string).pointer++) = (yaml_char_t) '\n',                               \
+      parser->buffer.pointer ++,                                                \
+      parser->mark.index ++,                                                    \
+      parser->mark.column = 0,                                                  \
+      parser->mark.line ++,                                                     \
+      parser->unread --) :                                                      \
+     (CHECK_AT(parser->buffer,'\xC2',0)                                         \
+      && CHECK_AT(parser->buffer,'\x85',1)) ?       /* NEL -> LF */             \
+     (*((string).pointer++) = (yaml_char_t) '\n',                               \
+      parser->buffer.pointer += 2,                                              \
+      parser->mark.index ++,                                                    \
+      parser->mark.column = 0,                                                  \
+      parser->mark.line ++,                                                     \
+      parser->unread --) :                                                      \
+     (CHECK_AT(parser->buffer,'\xE2',0) &&                                      \
+      CHECK_AT(parser->buffer,'\x80',1) &&                                      \
+      (CHECK_AT(parser->buffer,'\xA8',2) ||                                     \
+       CHECK_AT(parser->buffer,'\xA9',2))) ?        /* LS|PS -> LS|PS */        \
+     (*((string).pointer++) = *(parser->buffer.pointer++),                      \
+      *((string).pointer++) = *(parser->buffer.pointer++),                      \
+      *((string).pointer++) = *(parser->buffer.pointer++),                      \
+      parser->mark.index ++,                                                    \
+      parser->mark.column = 0,                                                  \
+      parser->mark.line ++,                                                     \
+      parser->unread --) : 0),                                                  \
+    1) : 0)
+
+/*
+ * Public API declarations.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_scan(yaml_parser_t *parser, yaml_token_t *token);
+
+/*
+ * Error handling.
+ */
+
+static int
+yaml_parser_set_scanner_error(yaml_parser_t *parser, const char *context,
+        yaml_mark_t context_mark, const char *problem);
+
+/*
+ * High-level token API.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_fetch_more_tokens(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_next_token(yaml_parser_t *parser);
+
+/*
+ * Potential simple keys.
+ */
+
+static int
+yaml_parser_stale_simple_keys(yaml_parser_t *parser);
+
+static int
+yaml_parser_save_simple_key(yaml_parser_t *parser);
+
+static int
+yaml_parser_remove_simple_key(yaml_parser_t *parser);
+
+static int
+yaml_parser_increase_flow_level(yaml_parser_t *parser);
+
+static int
+yaml_parser_decrease_flow_level(yaml_parser_t *parser);
+
+/*
+ * Indentation treatment.
+ */
+
+static int
+yaml_parser_roll_indent(yaml_parser_t *parser, ptrdiff_t column,
+        ptrdiff_t number, yaml_token_type_t type, yaml_mark_t mark);
+
+static int
+yaml_parser_unroll_indent(yaml_parser_t *parser, ptrdiff_t column);
+
+/*
+ * Token fetchers.
+ */
+
+static int
+yaml_parser_fetch_stream_start(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_stream_end(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_directive(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_document_indicator(yaml_parser_t *parser,
+        yaml_token_type_t type);
+
+static int
+yaml_parser_fetch_flow_collection_start(yaml_parser_t *parser,
+        yaml_token_type_t type);
+
+static int
+yaml_parser_fetch_flow_collection_end(yaml_parser_t *parser,
+        yaml_token_type_t type);
+
+static int
+yaml_parser_fetch_flow_entry(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_block_entry(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_key(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_value(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_anchor(yaml_parser_t *parser, yaml_token_type_t type);
+
+static int
+yaml_parser_fetch_tag(yaml_parser_t *parser);
+
+static int
+yaml_parser_fetch_block_scalar(yaml_parser_t *parser, int literal);
+
+static int
+yaml_parser_fetch_flow_scalar(yaml_parser_t *parser, int single);
+
+static int
+yaml_parser_fetch_plain_scalar(yaml_parser_t *parser);
+
+/*
+ * Token scanners.
+ */
+
+static int
+yaml_parser_scan_to_next_token(yaml_parser_t *parser);
+
+static int
+yaml_parser_scan_directive(yaml_parser_t *parser, yaml_token_t *token);
+
+static int
+yaml_parser_scan_directive_name(yaml_parser_t *parser,
+        yaml_mark_t start_mark, yaml_char_t **name);
+
+static int
+yaml_parser_scan_version_directive_value(yaml_parser_t *parser,
+        yaml_mark_t start_mark, int *major, int *minor);
+
+static int
+yaml_parser_scan_version_directive_number(yaml_parser_t *parser,
+        yaml_mark_t start_mark, int *number);
+
+static int
+yaml_parser_scan_tag_directive_value(yaml_parser_t *parser,
+        yaml_mark_t mark, yaml_char_t **handle, yaml_char_t **prefix);
+
+static int
+yaml_parser_scan_anchor(yaml_parser_t *parser, yaml_token_t *token,
+        yaml_token_type_t type);
+
+static int
+yaml_parser_scan_tag(yaml_parser_t *parser, yaml_token_t *token);
+
+static int
+yaml_parser_scan_tag_handle(yaml_parser_t *parser, int directive,
+        yaml_mark_t start_mark, yaml_char_t **handle);
+
+static int
+yaml_parser_scan_tag_uri(yaml_parser_t *parser, int uri_char, int directive,
+        yaml_char_t *head, yaml_mark_t start_mark, yaml_char_t **uri);
+
+static int
+yaml_parser_scan_uri_escapes(yaml_parser_t *parser, int directive,
+        yaml_mark_t start_mark, yaml_string_t *string);
+
+static int
+yaml_parser_scan_block_scalar(yaml_parser_t *parser, yaml_token_t *token,
+        int literal);
+
+static int
+yaml_parser_scan_block_scalar_breaks(yaml_parser_t *parser,
+        int *indent, yaml_string_t *breaks,
+        yaml_mark_t start_mark, yaml_mark_t *end_mark);
+
+static int
+yaml_parser_scan_flow_scalar(yaml_parser_t *parser, yaml_token_t *token,
+        int single);
+
+static int
+yaml_parser_scan_plain_scalar(yaml_parser_t *parser, yaml_token_t *token);
+
+/*
+ * Get the next token.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_scan(yaml_parser_t *parser, yaml_token_t *token)
+{
+    assert(parser); /* Non-NULL parser object is expected. */
+    assert(token);  /* Non-NULL token object is expected. */
+
+    /* Erase the token object. */
+
+    memset(token, 0, sizeof(yaml_token_t));
+
+    /* No tokens after STREAM-END or error. */
+
+    if (parser->stream_end_produced || parser->error) {
+        return 1;
+    }
+
+    /* Ensure that the tokens queue contains enough tokens. */
+
+    if (!parser->token_available) {
+        if (!yaml_parser_fetch_more_tokens(parser))
+            return 0;
+    }
+
+    /* Fetch the next token from the queue. */
+
+    *token = DEQUEUE(parser, parser->tokens);
+    parser->token_available = 0;
+    parser->tokens_parsed ++;
+
+    if (token->type == YAML_STREAM_END_TOKEN) {
+        parser->stream_end_produced = 1;
+    }
+
+    return 1;
+}
+
+/*
+ * Set the scanner error and return 0.
+ */
+
+static int
+yaml_parser_set_scanner_error(yaml_parser_t *parser, const char *context,
+        yaml_mark_t context_mark, const char *problem)
+{
+    parser->error = YAML_SCANNER_ERROR;
+    parser->context = context;
+    parser->context_mark = context_mark;
+    parser->problem = problem;
+    parser->problem_mark = parser->mark;
+
+    return 0;
+}
+
+/*
+ * Ensure that the tokens queue contains at least one token which can be
+ * returned to the Parser.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_fetch_more_tokens(yaml_parser_t *parser)
+{
+    int need_more_tokens;
+
+    /* While we need more tokens to fetch, do it. */
+
+    while (1)
+    {
+        /*
+         * Check if we really need to fetch more tokens.
+         */
+
+        need_more_tokens = 0;
+
+        if (parser->tokens.head == parser->tokens.tail)
+        {
+            /* Queue is empty. */
+
+            need_more_tokens = 1;
+        }
+        else
+        {
+            yaml_simple_key_t *simple_key;
+
+            /* Check if any potential simple key may occupy the head position. */
+
+            if (!yaml_parser_stale_simple_keys(parser))
+                return 0;
+
+            for (simple_key = parser->simple_keys.start;
+                    simple_key != parser->simple_keys.top; simple_key++) {
+                if (simple_key->possible
+                        && simple_key->token_number == parser->tokens_parsed) {
+                    need_more_tokens = 1;
+                    break;
+                }
+            }
+        }
+
+        /* We are finished. */
+
+        if (!need_more_tokens)
+            break;
+
+        /* Fetch the next token. */
+
+        if (!yaml_parser_fetch_next_token(parser))
+            return 0;
+    }
+
+    parser->token_available = 1;
+
+    return 1;
+}
+
+/*
+ * The dispatcher for token fetchers.
+ */
+
+static int
+yaml_parser_fetch_next_token(yaml_parser_t *parser)
+{
+    /* Ensure that the buffer is initialized. */
+
+    if (!CACHE(parser, 1))
+        return 0;
+
+    /* Check if we just started scanning.  Fetch STREAM-START then. */
+
+    if (!parser->stream_start_produced)
+        return yaml_parser_fetch_stream_start(parser);
+
+    /* Eat whitespaces and comments until we reach the next token. */
+
+    if (!yaml_parser_scan_to_next_token(parser))
+        return 0;
+
+    /* Remove obsolete potential simple keys. */
+
+    if (!yaml_parser_stale_simple_keys(parser))
+        return 0;
+
+    /* Check the indentation level against the current column. */
+
+    if (!yaml_parser_unroll_indent(parser, parser->mark.column))
+        return 0;
+
+    /*
+     * Ensure that the buffer contains at least 4 characters.  4 is the length
+     * of the longest indicators ('--- ' and '... ').
+     */
+
+    if (!CACHE(parser, 4))
+        return 0;
+
+    /* Is it the end of the stream? */
+
+    if (IS_Z(parser->buffer))
+        return yaml_parser_fetch_stream_end(parser);
+
+    /* Is it a directive? */
+
+    if (parser->mark.column == 0 && CHECK(parser->buffer, '%'))
+        return yaml_parser_fetch_directive(parser);
+
+    /* Is it the document start indicator? */
+
+    if (parser->mark.column == 0
+            && CHECK_AT(parser->buffer, '-', 0)
+            && CHECK_AT(parser->buffer, '-', 1)
+            && CHECK_AT(parser->buffer, '-', 2)
+            && IS_BLANKZ_AT(parser->buffer, 3))
+        return yaml_parser_fetch_document_indicator(parser,
+                YAML_DOCUMENT_START_TOKEN);
+
+    /* Is it the document end indicator? */
+
+    if (parser->mark.column == 0
+            && CHECK_AT(parser->buffer, '.', 0)
+            && CHECK_AT(parser->buffer, '.', 1)
+            && CHECK_AT(parser->buffer, '.', 2)
+            && IS_BLANKZ_AT(parser->buffer, 3))
+        return yaml_parser_fetch_document_indicator(parser,
+                YAML_DOCUMENT_END_TOKEN);
+
+    /* Is it the flow sequence start indicator? */
+
+    if (CHECK(parser->buffer, '['))
+        return yaml_parser_fetch_flow_collection_start(parser,
+                YAML_FLOW_SEQUENCE_START_TOKEN);
+
+    /* Is it the flow mapping start indicator? */
+
+    if (CHECK(parser->buffer, '{'))
+        return yaml_parser_fetch_flow_collection_start(parser,
+                YAML_FLOW_MAPPING_START_TOKEN);
+
+    /* Is it the flow sequence end indicator? */
+
+    if (CHECK(parser->buffer, ']'))
+        return yaml_parser_fetch_flow_collection_end(parser,
+                YAML_FLOW_SEQUENCE_END_TOKEN);
+
+    /* Is it the flow mapping end indicator? */
+
+    if (CHECK(parser->buffer, '}'))
+        return yaml_parser_fetch_flow_collection_end(parser,
+                YAML_FLOW_MAPPING_END_TOKEN);
+
+    /* Is it the flow entry indicator? */
+
+    if (CHECK(parser->buffer, ','))
+        return yaml_parser_fetch_flow_entry(parser);
+
+    /* Is it the block entry indicator? */
+
+    if (CHECK(parser->buffer, '-') && IS_BLANKZ_AT(parser->buffer, 1))
+        return yaml_parser_fetch_block_entry(parser);
+
+    /* Is it the key indicator? */
+
+    if (CHECK(parser->buffer, '?')
+            && (parser->flow_level || IS_BLANKZ_AT(parser->buffer, 1)))
+        return yaml_parser_fetch_key(parser);
+
+    /* Is it the value indicator? */
+
+    if (CHECK(parser->buffer, ':')
+            && (parser->flow_level || IS_BLANKZ_AT(parser->buffer, 1)))
+        return yaml_parser_fetch_value(parser);
+
+    /* Is it an alias? */
+
+    if (CHECK(parser->buffer, '*'))
+        return yaml_parser_fetch_anchor(parser, YAML_ALIAS_TOKEN);
+
+    /* Is it an anchor? */
+
+    if (CHECK(parser->buffer, '&'))
+        return yaml_parser_fetch_anchor(parser, YAML_ANCHOR_TOKEN);
+
+    /* Is it a tag? */
+
+    if (CHECK(parser->buffer, '!'))
+        return yaml_parser_fetch_tag(parser);
+
+    /* Is it a literal scalar? */
+
+    if (CHECK(parser->buffer, '|') && !parser->flow_level)
+        return yaml_parser_fetch_block_scalar(parser, 1);
+
+    /* Is it a folded scalar? */
+
+    if (CHECK(parser->buffer, '>') && !parser->flow_level)
+        return yaml_parser_fetch_block_scalar(parser, 0);
+
+    /* Is it a single-quoted scalar? */
+
+    if (CHECK(parser->buffer, '\''))
+        return yaml_parser_fetch_flow_scalar(parser, 1);
+
+    /* Is it a double-quoted scalar? */
+
+    if (CHECK(parser->buffer, '"'))
+        return yaml_parser_fetch_flow_scalar(parser, 0);
+
+    /*
+     * Is it a plain scalar?
+     *
+     * A plain scalar may start with any non-blank characters except
+     *
+     *      '-', '?', ':', ',', '[', ']', '{', '}',
+     *      '#', '&', '*', '!', '|', '>', '\'', '\"',
+     *      '%', '@', '`'.
+     *
+     * In the block context (and, for the '-' indicator, in the flow context
+     * too), it may also start with the characters
+     *
+     *      '-', '?', ':'
+     *
+     * if it is followed by a non-space character.
+     *
+     * The last rule is more restrictive than the specification requires.
+     */
+
+    if (!(IS_BLANKZ(parser->buffer) || CHECK(parser->buffer, '-')
+                || CHECK(parser->buffer, '?') || CHECK(parser->buffer, ':')
+                || CHECK(parser->buffer, ',') || CHECK(parser->buffer, '[')
+                || CHECK(parser->buffer, ']') || CHECK(parser->buffer, '{')
+                || CHECK(parser->buffer, '}') || CHECK(parser->buffer, '#')
+                || CHECK(parser->buffer, '&') || CHECK(parser->buffer, '*')
+                || CHECK(parser->buffer, '!') || CHECK(parser->buffer, '|')
+                || CHECK(parser->buffer, '>') || CHECK(parser->buffer, '\'')
+                || CHECK(parser->buffer, '"') || CHECK(parser->buffer, '%')
+                || CHECK(parser->buffer, '@') || CHECK(parser->buffer, '`')) ||
+            (CHECK(parser->buffer, '-') && !IS_BLANK_AT(parser->buffer, 1)) ||
+            (!parser->flow_level &&
+             (CHECK(parser->buffer, '?') || CHECK(parser->buffer, ':'))
+             && !IS_BLANKZ_AT(parser->buffer, 1)))
+        return yaml_parser_fetch_plain_scalar(parser);
+
+    /*
+     * If we don't determine the token type so far, it is an error.
+     */
+
+    return yaml_parser_set_scanner_error(parser,
+            "while scanning for the next token", parser->mark,
+            "found character that cannot start any token");
+}
+
+/*
+ * Check the list of potential simple keys and remove the positions that
+ * cannot contain simple keys anymore.
+ */
+
+static int
+yaml_parser_stale_simple_keys(yaml_parser_t *parser)
+{
+    yaml_simple_key_t *simple_key;
+
+    /* Check for a potential simple key for each flow level. */
+
+    for (simple_key = parser->simple_keys.start;
+            simple_key != parser->simple_keys.top; simple_key ++)
+    {
+        /*
+         * The specification requires that a simple key
+         *
+         *  - is limited to a single line,
+         *  - is shorter than 1024 characters.
+         */
+
+        if (simple_key->possible
+                && (simple_key->mark.line < parser->mark.line
+                    || simple_key->mark.index+1024 < parser->mark.index)) {
+
+            /* Check if the potential simple key to be removed is required. */
+
+            if (simple_key->required) {
+                return yaml_parser_set_scanner_error(parser,
+                        "while scanning a simple key", simple_key->mark,
+                        "could not find expected ':'");
+            }
+
+            simple_key->possible = 0;
+        }
+    }
+
+    return 1;
+}
+
+/*
+ * Check if a simple key may start at the current position and add it if
+ * needed.
+ */
+
+static int
+yaml_parser_save_simple_key(yaml_parser_t *parser)
+{
+    /*
+     * A simple key is required at the current position if the scanner is in
+     * the block context and the current column coincides with the indentation
+     * level.
+     */
+
+    int required = (!parser->flow_level
+            && parser->indent == (ptrdiff_t)parser->mark.column);
+
+    /*
+     * If the current position may start a simple key, save it.
+     */
+
+    if (parser->simple_key_allowed)
+    {
+        yaml_simple_key_t simple_key;
+        simple_key.possible = 1;
+        simple_key.required = required;
+        simple_key.token_number =
+            parser->tokens_parsed + (parser->tokens.tail - parser->tokens.head);
+        simple_key.mark = parser->mark;
+
+        if (!yaml_parser_remove_simple_key(parser)) return 0;
+
+        *(parser->simple_keys.top-1) = simple_key;
+    }
+
+    return 1;
+}
+
+/*
+ * Remove a potential simple key at the current flow level.
+ */
+
+static int
+yaml_parser_remove_simple_key(yaml_parser_t *parser)
+{
+    yaml_simple_key_t *simple_key = parser->simple_keys.top-1;
+
+    if (simple_key->possible)
+    {
+        /* If the key is required, it is an error. */
+
+        if (simple_key->required) {
+            return yaml_parser_set_scanner_error(parser,
+                    "while scanning a simple key", simple_key->mark,
+                    "could not find expected ':'");
+        }
+    }
+
+    /* Remove the key from the stack. */
+
+    simple_key->possible = 0;
+
+    return 1;
+}
+
+/*
+ * Increase the flow level and resize the simple key list if needed.
+ */
+
+static int
+yaml_parser_increase_flow_level(yaml_parser_t *parser)
+{
+    yaml_simple_key_t empty_simple_key = { 0, 0, 0, { 0, 0, 0 } };
+
+    /* Reset the simple key on the next level. */
+
+    if (!PUSH(parser, parser->simple_keys, empty_simple_key))
+        return 0;
+
+    /* Increase the flow level. */
+
+    if (parser->flow_level == INT_MAX) {
+        parser->error = YAML_MEMORY_ERROR;
+        return 0;
+    }
+
+    parser->flow_level++;
+
+    return 1;
+}
+
+/*
+ * Decrease the flow level.
+ */
+
+static int
+yaml_parser_decrease_flow_level(yaml_parser_t *parser)
+{
+    if (parser->flow_level) {
+        parser->flow_level --;
+        (void)POP(parser, parser->simple_keys);
+    }
+
+    return 1;
+}
+
+/*
+ * Push the current indentation level to the stack and set the new level
+ * the current column is greater than the indentation level.  In this case,
+ * append or insert the specified token into the token queue.
+ *
+ */
+
+static int
+yaml_parser_roll_indent(yaml_parser_t *parser, ptrdiff_t column,
+        ptrdiff_t number, yaml_token_type_t type, yaml_mark_t mark)
+{
+    yaml_token_t token;
+
+    /* In the flow context, do nothing. */
+
+    if (parser->flow_level)
+        return 1;
+
+    if (parser->indent < column)
+    {
+        /*
+         * Push the current indentation level to the stack and set the new
+         * indentation level.
+         */
+
+        if (!PUSH(parser, parser->indents, parser->indent))
+            return 0;
+
+        if (column > INT_MAX) {
+            parser->error = YAML_MEMORY_ERROR;
+            return 0;
+        }
+
+        parser->indent = column;
+
+        /* Create a token and insert it into the queue. */
+
+        TOKEN_INIT(token, type, mark, mark);
+
+        if (number == -1) {
+            if (!ENQUEUE(parser, parser->tokens, token))
+                return 0;
+        }
+        else {
+            if (!QUEUE_INSERT(parser,
+                        parser->tokens, number - parser->tokens_parsed, token))
+                return 0;
+        }
+    }
+
+    return 1;
+}
+
+/*
+ * Pop indentation levels from the indents stack until the current level
+ * becomes less or equal to the column.  For each indentation level, append
+ * the BLOCK-END token.
+ */
+
+
+static int
+yaml_parser_unroll_indent(yaml_parser_t *parser, ptrdiff_t column)
+{
+    yaml_token_t token;
+
+    /* In the flow context, do nothing. */
+
+    if (parser->flow_level)
+        return 1;
+
+    /* Loop through the indentation levels in the stack. */
+
+    while (parser->indent > column)
+    {
+        /* Create a token and append it to the queue. */
+
+        TOKEN_INIT(token, YAML_BLOCK_END_TOKEN, parser->mark, parser->mark);
+
+        if (!ENQUEUE(parser, parser->tokens, token))
+            return 0;
+
+        /* Pop the indentation level. */
+
+        parser->indent = POP(parser, parser->indents);
+    }
+
+    return 1;
+}
+
+/*
+ * Initialize the scanner and produce the STREAM-START token.
+ */
+
+static int
+yaml_parser_fetch_stream_start(yaml_parser_t *parser)
+{
+    yaml_simple_key_t simple_key = { 0, 0, 0, { 0, 0, 0 } };
+    yaml_token_t token;
+
+    /* Set the initial indentation. */
+
+    parser->indent = -1;
+
+    /* Initialize the simple key stack. */
+
+    if (!PUSH(parser, parser->simple_keys, simple_key))
+        return 0;
+
+    /* A simple key is allowed at the beginning of the stream. */
+
+    parser->simple_key_allowed = 1;
+
+    /* We have started. */
+
+    parser->stream_start_produced = 1;
+
+    /* Create the STREAM-START token and append it to the queue. */
+
+    STREAM_START_TOKEN_INIT(token, parser->encoding,
+            parser->mark, parser->mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the STREAM-END token and shut down the scanner.
+ */
+
+static int
+yaml_parser_fetch_stream_end(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* Force new line. */
+
+    if (parser->mark.column != 0) {
+        parser->mark.column = 0;
+        parser->mark.line ++;
+    }
+
+    /* Reset the indentation level. */
+
+    if (!yaml_parser_unroll_indent(parser, -1))
+        return 0;
+
+    /* Reset simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the STREAM-END token and append it to the queue. */
+
+    STREAM_END_TOKEN_INIT(token, parser->mark, parser->mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce a VERSION-DIRECTIVE or TAG-DIRECTIVE token.
+ */
+
+static int
+yaml_parser_fetch_directive(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* Reset the indentation level. */
+
+    if (!yaml_parser_unroll_indent(parser, -1))
+        return 0;
+
+    /* Reset simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the YAML-DIRECTIVE or TAG-DIRECTIVE token. */
+
+    if (!yaml_parser_scan_directive(parser, &token))
+        return 0;
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the DOCUMENT-START or DOCUMENT-END token.
+ */
+
+static int
+yaml_parser_fetch_document_indicator(yaml_parser_t *parser,
+        yaml_token_type_t type)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Reset the indentation level. */
+
+    if (!yaml_parser_unroll_indent(parser, -1))
+        return 0;
+
+    /* Reset simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    parser->simple_key_allowed = 0;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+    SKIP(parser);
+    SKIP(parser);
+
+    end_mark = parser->mark;
+
+    /* Create the DOCUMENT-START or DOCUMENT-END token. */
+
+    TOKEN_INIT(token, type, start_mark, end_mark);
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the FLOW-SEQUENCE-START or FLOW-MAPPING-START token.
+ */
+
+static int
+yaml_parser_fetch_flow_collection_start(yaml_parser_t *parser,
+        yaml_token_type_t type)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* The indicators '[' and '{' may start a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* Increase the flow level. */
+
+    if (!yaml_parser_increase_flow_level(parser))
+        return 0;
+
+    /* A simple key may follow the indicators '[' and '{'. */
+
+    parser->simple_key_allowed = 1;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the FLOW-SEQUENCE-START of FLOW-MAPPING-START token. */
+
+    TOKEN_INIT(token, type, start_mark, end_mark);
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the FLOW-SEQUENCE-END or FLOW-MAPPING-END token.
+ */
+
+static int
+yaml_parser_fetch_flow_collection_end(yaml_parser_t *parser,
+        yaml_token_type_t type)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Reset any potential simple key on the current flow level. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* Decrease the flow level. */
+
+    if (!yaml_parser_decrease_flow_level(parser))
+        return 0;
+
+    /* No simple keys after the indicators ']' and '}'. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the FLOW-SEQUENCE-END of FLOW-MAPPING-END token. */
+
+    TOKEN_INIT(token, type, start_mark, end_mark);
+
+    /* Append the token to the queue. */
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the FLOW-ENTRY token.
+ */
+
+static int
+yaml_parser_fetch_flow_entry(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Reset any potential simple keys on the current flow level. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* Simple keys are allowed after ','. */
+
+    parser->simple_key_allowed = 1;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the FLOW-ENTRY token and append it to the queue. */
+
+    TOKEN_INIT(token, YAML_FLOW_ENTRY_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the BLOCK-ENTRY token.
+ */
+
+static int
+yaml_parser_fetch_block_entry(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* Check if the scanner is in the block context. */
+
+    if (!parser->flow_level)
+    {
+        /* Check if we are allowed to start a new entry. */
+
+        if (!parser->simple_key_allowed) {
+            return yaml_parser_set_scanner_error(parser, NULL, parser->mark,
+                    "block sequence entries are not allowed in this context");
+        }
+
+        /* Add the BLOCK-SEQUENCE-START token if needed. */
+
+        if (!yaml_parser_roll_indent(parser, parser->mark.column, -1,
+                    YAML_BLOCK_SEQUENCE_START_TOKEN, parser->mark))
+            return 0;
+    }
+    else
+    {
+        /*
+         * It is an error for the '-' indicator to occur in the flow context,
+         * but we let the Parser detect and report about it because the Parser
+         * is able to point to the context.
+         */
+    }
+
+    /* Reset any potential simple keys on the current flow level. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* Simple keys are allowed after '-'. */
+
+    parser->simple_key_allowed = 1;
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the BLOCK-ENTRY token and append it to the queue. */
+
+    TOKEN_INIT(token, YAML_BLOCK_ENTRY_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the KEY token.
+ */
+
+static int
+yaml_parser_fetch_key(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+
+    /* In the block context, additional checks are required. */
+
+    if (!parser->flow_level)
+    {
+        /* Check if we are allowed to start a new key (not necessary simple). */
+
+        if (!parser->simple_key_allowed) {
+            return yaml_parser_set_scanner_error(parser, NULL, parser->mark,
+                    "mapping keys are not allowed in this context");
+        }
+
+        /* Add the BLOCK-MAPPING-START token if needed. */
+
+        if (!yaml_parser_roll_indent(parser, parser->mark.column, -1,
+                    YAML_BLOCK_MAPPING_START_TOKEN, parser->mark))
+            return 0;
+    }
+
+    /* Reset any potential simple keys on the current flow level. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* Simple keys are allowed after '?' in the block context. */
+
+    parser->simple_key_allowed = (!parser->flow_level);
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the KEY token and append it to the queue. */
+
+    TOKEN_INIT(token, YAML_KEY_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the VALUE token.
+ */
+
+static int
+yaml_parser_fetch_value(yaml_parser_t *parser)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_token_t token;
+    yaml_simple_key_t *simple_key = parser->simple_keys.top-1;
+
+    /* Have we found a simple key? */
+
+    if (simple_key->possible)
+    {
+
+        /* Create the KEY token and insert it into the queue. */
+
+        TOKEN_INIT(token, YAML_KEY_TOKEN, simple_key->mark, simple_key->mark);
+
+        if (!QUEUE_INSERT(parser, parser->tokens,
+                    simple_key->token_number - parser->tokens_parsed, token))
+            return 0;
+
+        /* In the block context, we may need to add the BLOCK-MAPPING-START token. */
+
+        if (!yaml_parser_roll_indent(parser, simple_key->mark.column,
+                    simple_key->token_number,
+                    YAML_BLOCK_MAPPING_START_TOKEN, simple_key->mark))
+            return 0;
+
+        /* Remove the simple key. */
+
+        simple_key->possible = 0;
+
+        /* A simple key cannot follow another simple key. */
+
+        parser->simple_key_allowed = 0;
+    }
+    else
+    {
+        /* The ':' indicator follows a complex key. */
+
+        /* In the block context, extra checks are required. */
+
+        if (!parser->flow_level)
+        {
+            /* Check if we are allowed to start a complex value. */
+
+            if (!parser->simple_key_allowed) {
+                return yaml_parser_set_scanner_error(parser, NULL, parser->mark,
+                        "mapping values are not allowed in this context");
+            }
+
+            /* Add the BLOCK-MAPPING-START token if needed. */
+
+            if (!yaml_parser_roll_indent(parser, parser->mark.column, -1,
+                        YAML_BLOCK_MAPPING_START_TOKEN, parser->mark))
+                return 0;
+        }
+
+        /* Simple keys after ':' are allowed in the block context. */
+
+        parser->simple_key_allowed = (!parser->flow_level);
+    }
+
+    /* Consume the token. */
+
+    start_mark = parser->mark;
+    SKIP(parser);
+    end_mark = parser->mark;
+
+    /* Create the VALUE token and append it to the queue. */
+
+    TOKEN_INIT(token, YAML_VALUE_TOKEN, start_mark, end_mark);
+
+    if (!ENQUEUE(parser, parser->tokens, token))
+        return 0;
+
+    return 1;
+}
+
+/*
+ * Produce the ALIAS or ANCHOR token.
+ */
+
+static int
+yaml_parser_fetch_anchor(yaml_parser_t *parser, yaml_token_type_t type)
+{
+    yaml_token_t token;
+
+    /* An anchor or an alias could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow an anchor or an alias. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the ALIAS or ANCHOR token and append it to the queue. */
+
+    if (!yaml_parser_scan_anchor(parser, &token, type))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+    return 1;
+}
+
+/*
+ * Produce the TAG token.
+ */
+
+static int
+yaml_parser_fetch_tag(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* A tag could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow a tag. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the TAG token and append it to the queue. */
+
+    if (!yaml_parser_scan_tag(parser, &token))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the SCALAR(...,literal) or SCALAR(...,folded) tokens.
+ */
+
+static int
+yaml_parser_fetch_block_scalar(yaml_parser_t *parser, int literal)
+{
+    yaml_token_t token;
+
+    /* Remove any potential simple keys. */
+
+    if (!yaml_parser_remove_simple_key(parser))
+        return 0;
+
+    /* A simple key may follow a block scalar. */
+
+    parser->simple_key_allowed = 1;
+
+    /* Create the SCALAR token and append it to the queue. */
+
+    if (!yaml_parser_scan_block_scalar(parser, &token, literal))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the SCALAR(...,single-quoted) or SCALAR(...,double-quoted) tokens.
+ */
+
+static int
+yaml_parser_fetch_flow_scalar(yaml_parser_t *parser, int single)
+{
+    yaml_token_t token;
+
+    /* A plain scalar could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow a flow scalar. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the SCALAR token and append it to the queue. */
+
+    if (!yaml_parser_scan_flow_scalar(parser, &token, single))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Produce the SCALAR(...,plain) token.
+ */
+
+static int
+yaml_parser_fetch_plain_scalar(yaml_parser_t *parser)
+{
+    yaml_token_t token;
+
+    /* A plain scalar could be a simple key. */
+
+    if (!yaml_parser_save_simple_key(parser))
+        return 0;
+
+    /* A simple key cannot follow a flow scalar. */
+
+    parser->simple_key_allowed = 0;
+
+    /* Create the SCALAR token and append it to the queue. */
+
+    if (!yaml_parser_scan_plain_scalar(parser, &token))
+        return 0;
+
+    if (!ENQUEUE(parser, parser->tokens, token)) {
+        yaml_token_delete(&token);
+        return 0;
+    }
+
+    return 1;
+}
+
+/*
+ * Eat whitespaces and comments until the next token is found.
+ */
+
+static int
+yaml_parser_scan_to_next_token(yaml_parser_t *parser)
+{
+    /* Until the next token is not found. */
+
+    while (1)
+    {
+        /* Allow the BOM mark to start a line. */
+
+        if (!CACHE(parser, 1)) return 0;
+
+        if (parser->mark.column == 0 && IS_BOM(parser->buffer))
+            SKIP(parser);
+
+        /*
+         * Eat whitespaces.
+         *
+         * Tabs are allowed:
+         *
+         *  - in the flow context;
+         *  - in the block context, but not at the beginning of the line or
+         *  after '-', '?', or ':' (complex value).
+         */
+
+        if (!CACHE(parser, 1)) return 0;
+
+        while (CHECK(parser->buffer,' ') ||
+                ((parser->flow_level || !parser->simple_key_allowed) &&
+                 CHECK(parser->buffer, '\t'))) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) return 0;
+        }
+
+        /* Eat a comment until a line break. */
+
+        if (CHECK(parser->buffer, '#')) {
+            while (!IS_BREAKZ(parser->buffer)) {
+                SKIP(parser);
+                if (!CACHE(parser, 1)) return 0;
+            }
+        }
+
+        /* If it is a line break, eat it. */
+
+        if (IS_BREAK(parser->buffer))
+        {
+            if (!CACHE(parser, 2)) return 0;
+            SKIP_LINE(parser);
+
+            /* In the block context, a new line may start a simple key. */
+
+            if (!parser->flow_level) {
+                parser->simple_key_allowed = 1;
+            }
+        }
+        else
+        {
+            /* We have found a token. */
+
+            break;
+        }
+    }
+
+    return 1;
+}
+
+/*
+ * Scan a YAML-DIRECTIVE or TAG-DIRECTIVE token.
+ *
+ * Scope:
+ *      %YAML    1.1    # a comment \n
+ *      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ *      %TAG    !yaml!  tag:yaml.org,2002:  \n
+ *      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ */
+
+int
+yaml_parser_scan_directive(yaml_parser_t *parser, yaml_token_t *token)
+{
+    yaml_mark_t start_mark, end_mark;
+    yaml_char_t *name = NULL;
+    int major, minor;
+    yaml_char_t *handle = NULL, *prefix = NULL;
+
+    /* Eat '%'. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Scan the directive name. */
+
+    if (!yaml_parser_scan_directive_name(parser, start_mark, &name))
+        goto error;
+
+    /* Is it a YAML directive? */
+
+    if (strcmp((char *)name, "YAML") == 0)
+    {
+        /* Scan the VERSION directive value. */
+
+        if (!yaml_parser_scan_version_directive_value(parser, start_mark,
+                    &major, &minor))
+            goto error;
+
+        end_mark = parser->mark;
+
+        /* Create a VERSION-DIRECTIVE token. */
+
+        VERSION_DIRECTIVE_TOKEN_INIT(*token, major, minor,
+                start_mark, end_mark);
+    }
+
+    /* Is it a TAG directive? */
+
+    else if (strcmp((char *)name, "TAG") == 0)
+    {
+        /* Scan the TAG directive value. */
+
+        if (!yaml_parser_scan_tag_directive_value(parser, start_mark,
+                    &handle, &prefix))
+            goto error;
+
+        end_mark = parser->mark;
+
+        /* Create a TAG-DIRECTIVE token. */
+
+        TAG_DIRECTIVE_TOKEN_INIT(*token, handle, prefix,
+                start_mark, end_mark);
+    }
+
+    /* Unknown directive. */
+
+    else
+    {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "found unknown directive name");
+        goto error;
+    }
+
+    /* Eat the rest of the line including any comments. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    if (CHECK(parser->buffer, '#')) {
+        while (!IS_BREAKZ(parser->buffer)) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) goto error;
+        }
+    }
+
+    /* Check if we are at the end of the line. */
+
+    if (!IS_BREAKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "did not find expected comment or line break");
+        goto error;
+    }
+
+    /* Eat a line break. */
+
+    if (IS_BREAK(parser->buffer)) {
+        if (!CACHE(parser, 2)) goto error;
+        SKIP_LINE(parser);
+    }
+
+    yaml_free(name);
+
+    return 1;
+
+error:
+    yaml_free(prefix);
+    yaml_free(handle);
+    yaml_free(name);
+    return 0;
+}
+
+/*
+ * Scan the directive name.
+ *
+ * Scope:
+ *      %YAML   1.1     # a comment \n
+ *       ^^^^
+ *      %TAG    !yaml!  tag:yaml.org,2002:  \n
+ *       ^^^
+ */
+
+static int
+yaml_parser_scan_directive_name(yaml_parser_t *parser,
+        yaml_mark_t start_mark, yaml_char_t **name)
+{
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Consume the directive name. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_ALPHA(parser->buffer))
+    {
+        if (!READ(parser, string)) goto error;
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Check if the name is empty. */
+
+    if (string.start == string.pointer) {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "could not find expected directive name");
+        goto error;
+    }
+
+    /* Check for an blank character after the name. */
+
+    if (!IS_BLANKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a directive",
+                start_mark, "found unexpected non-alphabetical character");
+        goto error;
+    }
+
+    *name = string.start;
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Scan the value of VERSION-DIRECTIVE.
+ *
+ * Scope:
+ *      %YAML   1.1     # a comment \n
+ *           ^^^^^^
+ */
+
+static int
+yaml_parser_scan_version_directive_value(yaml_parser_t *parser,
+        yaml_mark_t start_mark, int *major, int *minor)
+{
+    /* Eat whitespaces. */
+
+    if (!CACHE(parser, 1)) return 0;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) return 0;
+    }
+
+    /* Consume the major version number. */
+
+    if (!yaml_parser_scan_version_directive_number(parser, start_mark, major))
+        return 0;
+
+    /* Eat '.'. */
+
+    if (!CHECK(parser->buffer, '.')) {
+        return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
+                start_mark, "did not find expected digit or '.' character");
+    }
+
+    SKIP(parser);
+
+    /* Consume the minor version number. */
+
+    if (!yaml_parser_scan_version_directive_number(parser, start_mark, minor))
+        return 0;
+
+    return 1;
+}
+
+#define MAX_NUMBER_LENGTH   9
+
+/*
+ * Scan the version number of VERSION-DIRECTIVE.
+ *
+ * Scope:
+ *      %YAML   1.1     # a comment \n
+ *              ^
+ *      %YAML   1.1     # a comment \n
+ *                ^
+ */
+
+static int
+yaml_parser_scan_version_directive_number(yaml_parser_t *parser,
+        yaml_mark_t start_mark, int *number)
+{
+    int value = 0;
+    size_t length = 0;
+
+    /* Repeat while the next character is digit. */
+
+    if (!CACHE(parser, 1)) return 0;
+
+    while (IS_DIGIT(parser->buffer))
+    {
+        /* Check if the number is too long. */
+
+        if (++length > MAX_NUMBER_LENGTH) {
+            return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
+                    start_mark, "found extremely long version number");
+        }
+
+        value = value*10 + AS_DIGIT(parser->buffer);
+
+        SKIP(parser);
+
+        if (!CACHE(parser, 1)) return 0;
+    }
+
+    /* Check if the number was present. */
+
+    if (!length) {
+        return yaml_parser_set_scanner_error(parser, "while scanning a %YAML directive",
+                start_mark, "did not find expected version number");
+    }
+
+    *number = value;
+
+    return 1;
+}
+
+/*
+ * Scan the value of a TAG-DIRECTIVE token.
+ *
+ * Scope:
+ *      %TAG    !yaml!  tag:yaml.org,2002:  \n
+ *          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ */
+
+static int
+yaml_parser_scan_tag_directive_value(yaml_parser_t *parser,
+        yaml_mark_t start_mark, yaml_char_t **handle, yaml_char_t **prefix)
+{
+    yaml_char_t *handle_value = NULL;
+    yaml_char_t *prefix_value = NULL;
+
+    /* Eat whitespaces. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Scan a handle. */
+
+    if (!yaml_parser_scan_tag_handle(parser, 1, start_mark, &handle_value))
+        goto error;
+
+    /* Expect a whitespace. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!IS_BLANK(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
+                start_mark, "did not find expected whitespace");
+        goto error;
+    }
+
+    /* Eat whitespaces. */
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Scan a prefix. */
+
+    if (!yaml_parser_scan_tag_uri(parser, 1, 1, NULL, start_mark, &prefix_value))
+        goto error;
+
+    /* Expect a whitespace or line break. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!IS_BLANKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a %TAG directive",
+                start_mark, "did not find expected whitespace or line break");
+        goto error;
+    }
+
+    *handle = handle_value;
+    *prefix = prefix_value;
+
+    return 1;
+
+error:
+    yaml_free(handle_value);
+    yaml_free(prefix_value);
+    return 0;
+}
+
+static int
+yaml_parser_scan_anchor(yaml_parser_t *parser, yaml_token_t *token,
+        yaml_token_type_t type)
+{
+    int length = 0;
+    yaml_mark_t start_mark, end_mark;
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Eat the indicator character. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Consume the value. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_ALPHA(parser->buffer)) {
+        if (!READ(parser, string)) goto error;
+        if (!CACHE(parser, 1)) goto error;
+        length ++;
+    }
+
+    end_mark = parser->mark;
+
+    /*
+     * Check if length of the anchor is greater than 0 and it is followed by
+     * a whitespace character or one of the indicators:
+     *
+     *      '?', ':', ',', ']', '}', '%', '@', '`'.
+     */
+
+    if (!length || !(IS_BLANKZ(parser->buffer) || CHECK(parser->buffer, '?')
+                || CHECK(parser->buffer, ':') || CHECK(parser->buffer, ',')
+                || CHECK(parser->buffer, ']') || CHECK(parser->buffer, '}')
+                || CHECK(parser->buffer, '%') || CHECK(parser->buffer, '@')
+                || CHECK(parser->buffer, '`'))) {
+        yaml_parser_set_scanner_error(parser, type == YAML_ANCHOR_TOKEN ?
+                "while scanning an anchor" : "while scanning an alias", start_mark,
+                "did not find expected alphabetic or numeric character");
+        goto error;
+    }
+
+    /* Create a token. */
+
+    if (type == YAML_ANCHOR_TOKEN) {
+        ANCHOR_TOKEN_INIT(*token, string.start, start_mark, end_mark);
+    }
+    else {
+        ALIAS_TOKEN_INIT(*token, string.start, start_mark, end_mark);
+    }
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Scan a TAG token.
+ */
+
+static int
+yaml_parser_scan_tag(yaml_parser_t *parser, yaml_token_t *token)
+{
+    yaml_char_t *handle = NULL;
+    yaml_char_t *suffix = NULL;
+    yaml_mark_t start_mark, end_mark;
+
+    start_mark = parser->mark;
+
+    /* Check if the tag is in the canonical form. */
+
+    if (!CACHE(parser, 2)) goto error;
+
+    if (CHECK_AT(parser->buffer, '<', 1))
+    {
+        /* Set the handle to '' */
+
+        handle = YAML_MALLOC(1);
+        if (!handle) goto error;
+        handle[0] = '\0';
+
+        /* Eat '!<' */
+
+        SKIP(parser);
+        SKIP(parser);
+
+        /* Consume the tag value. */
+
+        if (!yaml_parser_scan_tag_uri(parser, 1, 0, NULL, start_mark, &suffix))
+            goto error;
+
+        /* Check for '>' and eat it. */
+
+        if (!CHECK(parser->buffer, '>')) {
+            yaml_parser_set_scanner_error(parser, "while scanning a tag",
+                    start_mark, "did not find the expected '>'");
+            goto error;
+        }
+
+        SKIP(parser);
+    }
+    else
+    {
+        /* The tag has either the '!suffix' or the '!handle!suffix' form. */
+
+        /* First, try to scan a handle. */
+
+        if (!yaml_parser_scan_tag_handle(parser, 0, start_mark, &handle))
+            goto error;
+
+        /* Check if it is, indeed, handle. */
+
+        if (handle[0] == '!' && handle[1] != '\0' && handle[strlen((char *)handle)-1] == '!')
+        {
+            /* Scan the suffix now. */
+
+            if (!yaml_parser_scan_tag_uri(parser, 0, 0, NULL, start_mark, &suffix))
+                goto error;
+        }
+        else
+        {
+            /* It wasn't a handle after all.  Scan the rest of the tag. */
+
+            if (!yaml_parser_scan_tag_uri(parser, 0, 0, handle, start_mark, &suffix))
+                goto error;
+
+            /* Set the handle to '!'. */
+
+            yaml_free(handle);
+            handle = YAML_MALLOC(2);
+            if (!handle) goto error;
+            handle[0] = '!';
+            handle[1] = '\0';
+
+            /*
+             * A special case: the '!' tag.  Set the handle to '' and the
+             * suffix to '!'.
+             */
+
+            if (suffix[0] == '\0') {
+                yaml_char_t *tmp = handle;
+                handle = suffix;
+                suffix = tmp;
+            }
+        }
+    }
+
+    /* Check the character which ends the tag. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!IS_BLANKZ(parser->buffer)) {
+        if (!parser->flow_level || !CHECK(parser->buffer, ',') ) {
+            yaml_parser_set_scanner_error(parser, "while scanning a tag",
+                    start_mark, "did not find expected whitespace or line break");
+            goto error;
+        }
+    }
+
+    end_mark = parser->mark;
+
+    /* Create a token. */
+
+    TAG_TOKEN_INIT(*token, handle, suffix, start_mark, end_mark);
+
+    return 1;
+
+error:
+    yaml_free(handle);
+    yaml_free(suffix);
+    return 0;
+}
+
+/*
+ * Scan a tag handle.
+ */
+
+static int
+yaml_parser_scan_tag_handle(yaml_parser_t *parser, int directive,
+        yaml_mark_t start_mark, yaml_char_t **handle)
+{
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Check the initial '!' character. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    if (!CHECK(parser->buffer, '!')) {
+        yaml_parser_set_scanner_error(parser, directive ?
+                "while scanning a tag directive" : "while scanning a tag",
+                start_mark, "did not find expected '!'");
+        goto error;
+    }
+
+    /* Copy the '!' character. */
+
+    if (!READ(parser, string)) goto error;
+
+    /* Copy all subsequent alphabetical and numerical characters. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_ALPHA(parser->buffer))
+    {
+        if (!READ(parser, string)) goto error;
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Check if the trailing character is '!' and copy it. */
+
+    if (CHECK(parser->buffer, '!'))
+    {
+        if (!READ(parser, string)) goto error;
+    }
+    else
+    {
+        /*
+         * It's either the '!' tag or not really a tag handle.  If it's a %TAG
+         * directive, it's an error.  If it's a tag token, it must be a part of
+         * URI.
+         */
+
+        if (directive && !(string.start[0] == '!' && string.start[1] == '\0')) {
+            yaml_parser_set_scanner_error(parser, "while parsing a tag directive",
+                    start_mark, "did not find expected '!'");
+            goto error;
+        }
+    }
+
+    *handle = string.start;
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Scan a tag.
+ */
+
+static int
+yaml_parser_scan_tag_uri(yaml_parser_t *parser, int uri_char, int directive,
+        yaml_char_t *head, yaml_mark_t start_mark, yaml_char_t **uri)
+{
+    size_t length = head ? strlen((char *)head) : 0;
+    yaml_string_t string = NULL_STRING;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+
+    /* Resize the string to include the head. */
+
+    while ((size_t)(string.end - string.start) <= length) {
+        if (!yaml_string_extend(&string.start, &string.pointer, &string.end)) {
+            parser->error = YAML_MEMORY_ERROR;
+            goto error;
+        }
+    }
+
+    /*
+     * Copy the head if needed.
+     *
+     * Note that we don't copy the leading '!' character.
+     */
+
+    if (length > 1) {
+        memcpy(string.start, head+1, length-1);
+        string.pointer += length-1;
+    }
+
+    /* Scan the tag. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    /*
+     * The set of characters that may appear in URI is as follows:
+     *
+     *      '0'-'9', 'A'-'Z', 'a'-'z', '_', '-', ';', '/', '?', ':', '@', '&',
+     *      '=', '+', '$', '.', '!', '~', '*', '\'', '(', ')', '%'.
+     *
+     * If we are inside a verbatim tag <...> (parameter uri_char is true)
+     * then also the following flow indicators are allowed:
+     *      ',', '[', ']'
+     */
+
+    while (IS_ALPHA(parser->buffer) || CHECK(parser->buffer, ';')
+            || CHECK(parser->buffer, '/') || CHECK(parser->buffer, '?')
+            || CHECK(parser->buffer, ':') || CHECK(parser->buffer, '@')
+            || CHECK(parser->buffer, '&') || CHECK(parser->buffer, '=')
+            || CHECK(parser->buffer, '+') || CHECK(parser->buffer, '$')
+            || CHECK(parser->buffer, '.') || CHECK(parser->buffer, '%')
+            || CHECK(parser->buffer, '!') || CHECK(parser->buffer, '~')
+            || CHECK(parser->buffer, '*') || CHECK(parser->buffer, '\'')
+            || CHECK(parser->buffer, '(') || CHECK(parser->buffer, ')')
+            || (uri_char && (
+                CHECK(parser->buffer, ',')
+                || CHECK(parser->buffer, '[') || CHECK(parser->buffer, ']')
+                )
+            ))
+    {
+        /* Check if it is a URI-escape sequence. */
+
+        if (CHECK(parser->buffer, '%')) {
+            if (!STRING_EXTEND(parser, string))
+                goto error;
+
+            if (!yaml_parser_scan_uri_escapes(parser,
+                        directive, start_mark, &string)) goto error;
+        }
+        else {
+            if (!READ(parser, string)) goto error;
+        }
+
+        length ++;
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    /* Check if the tag is non-empty. */
+
+    if (!length) {
+        if (!STRING_EXTEND(parser, string))
+            goto error;
+
+        yaml_parser_set_scanner_error(parser, directive ?
+                "while parsing a %TAG directive" : "while parsing a tag",
+                start_mark, "did not find expected tag URI");
+        goto error;
+    }
+
+    *uri = string.start;
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    return 0;
+}
+
+/*
+ * Decode an URI-escape sequence corresponding to a single UTF-8 character.
+ */
+
+static int
+yaml_parser_scan_uri_escapes(yaml_parser_t *parser, int directive,
+        yaml_mark_t start_mark, yaml_string_t *string)
+{
+    int width = 0;
+
+    /* Decode the required number of characters. */
+
+    do {
+
+        unsigned char octet = 0;
+
+        /* Check for a URI-escaped octet. */
+
+        if (!CACHE(parser, 3)) return 0;
+
+        if (!(CHECK(parser->buffer, '%')
+                    && IS_HEX_AT(parser->buffer, 1)
+                    && IS_HEX_AT(parser->buffer, 2))) {
+            return yaml_parser_set_scanner_error(parser, directive ?
+                    "while parsing a %TAG directive" : "while parsing a tag",
+                    start_mark, "did not find URI escaped octet");
+        }
+
+        /* Get the octet. */
+
+        octet = (AS_HEX_AT(parser->buffer, 1) << 4) + AS_HEX_AT(parser->buffer, 2);
+
+        /* If it is the leading octet, determine the length of the UTF-8 sequence. */
+
+        if (!width)
+        {
+            width = (octet & 0x80) == 0x00 ? 1 :
+                    (octet & 0xE0) == 0xC0 ? 2 :
+                    (octet & 0xF0) == 0xE0 ? 3 :
+                    (octet & 0xF8) == 0xF0 ? 4 : 0;
+            if (!width) {
+                return yaml_parser_set_scanner_error(parser, directive ?
+                        "while parsing a %TAG directive" : "while parsing a tag",
+                        start_mark, "found an incorrect leading UTF-8 octet");
+            }
+        }
+        else
+        {
+            /* Check if the trailing octet is correct. */
+
+            if ((octet & 0xC0) != 0x80) {
+                return yaml_parser_set_scanner_error(parser, directive ?
+                        "while parsing a %TAG directive" : "while parsing a tag",
+                        start_mark, "found an incorrect trailing UTF-8 octet");
+            }
+        }
+
+        /* Copy the octet and move the pointers. */
+
+        *(string->pointer++) = octet;
+        SKIP(parser);
+        SKIP(parser);
+        SKIP(parser);
+
+    } while (--width);
+
+    return 1;
+}
+
+/*
+ * Scan a block scalar.
+ */
+
+static int
+yaml_parser_scan_block_scalar(yaml_parser_t *parser, yaml_token_t *token,
+        int literal)
+{
+    yaml_mark_t start_mark;
+    yaml_mark_t end_mark;
+    yaml_string_t string = NULL_STRING;
+    yaml_string_t leading_break = NULL_STRING;
+    yaml_string_t trailing_breaks = NULL_STRING;
+    int chomping = 0;
+    int increment = 0;
+    int indent = 0;
+    int leading_blank = 0;
+    int trailing_blank = 0;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
+
+    /* Eat the indicator '|' or '>'. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Scan the additional block scalar indicators. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    /* Check for a chomping indicator. */
+
+    if (CHECK(parser->buffer, '+') || CHECK(parser->buffer, '-'))
+    {
+        /* Set the chomping method and eat the indicator. */
+
+        chomping = CHECK(parser->buffer, '+') ? +1 : -1;
+
+        SKIP(parser);
+
+        /* Check for an indentation indicator. */
+
+        if (!CACHE(parser, 1)) goto error;
+
+        if (IS_DIGIT(parser->buffer))
+        {
+            /* Check that the indentation is greater than 0. */
+
+            if (CHECK(parser->buffer, '0')) {
+                yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                        start_mark, "found an indentation indicator equal to 0");
+                goto error;
+            }
+
+            /* Get the indentation level and eat the indicator. */
+
+            increment = AS_DIGIT(parser->buffer);
+
+            SKIP(parser);
+        }
+    }
+
+    /* Do the same as above, but in the opposite order. */
+
+    else if (IS_DIGIT(parser->buffer))
+    {
+        if (CHECK(parser->buffer, '0')) {
+            yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                    start_mark, "found an indentation indicator equal to 0");
+            goto error;
+        }
+
+        increment = AS_DIGIT(parser->buffer);
+
+        SKIP(parser);
+
+        if (!CACHE(parser, 1)) goto error;
+
+        if (CHECK(parser->buffer, '+') || CHECK(parser->buffer, '-')) {
+            chomping = CHECK(parser->buffer, '+') ? +1 : -1;
+
+            SKIP(parser);
+        }
+    }
+
+    /* Eat whitespaces and comments to the end of the line. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while (IS_BLANK(parser->buffer)) {
+        SKIP(parser);
+        if (!CACHE(parser, 1)) goto error;
+    }
+
+    if (CHECK(parser->buffer, '#')) {
+        while (!IS_BREAKZ(parser->buffer)) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) goto error;
+        }
+    }
+
+    /* Check if we are at the end of the line. */
+
+    if (!IS_BREAKZ(parser->buffer)) {
+        yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                start_mark, "did not find expected comment or line break");
+        goto error;
+    }
+
+    /* Eat a line break. */
+
+    if (IS_BREAK(parser->buffer)) {
+        if (!CACHE(parser, 2)) goto error;
+        SKIP_LINE(parser);
+    }
+
+    end_mark = parser->mark;
+
+    /* Set the indentation level if it was specified. */
+
+    if (increment) {
+        indent = parser->indent >= 0 ? parser->indent+increment : increment;
+    }
+
+    /* Scan the leading line breaks and determine the indentation level if needed. */
+
+    if (!yaml_parser_scan_block_scalar_breaks(parser, &indent, &trailing_breaks,
+                start_mark, &end_mark)) goto error;
+
+    /* Scan the block scalar content. */
+
+    if (!CACHE(parser, 1)) goto error;
+
+    while ((int)parser->mark.column == indent && !(IS_Z(parser->buffer)))
+    {
+        /*
+         * We are at the beginning of a non-empty line.
+         */
+
+        /* Is it a trailing whitespace? */
+
+        trailing_blank = IS_BLANK(parser->buffer);
+
+        /* Check if we need to fold the leading line break. */
+
+        if (!literal && (*leading_break.start == '\n')
+                && !leading_blank && !trailing_blank)
+        {
+            /* Do we need to join the lines by space? */
+
+            if (*trailing_breaks.start == '\0') {
+                if (!STRING_EXTEND(parser, string)) goto error;
+                *(string.pointer ++) = ' ';
+            }
+
+            CLEAR(parser, leading_break);
+        }
+        else {
+            if (!JOIN(parser, string, leading_break)) goto error;
+            CLEAR(parser, leading_break);
+        }
+
+        /* Append the remaining line breaks. */
+
+        if (!JOIN(parser, string, trailing_breaks)) goto error;
+        CLEAR(parser, trailing_breaks);
+
+        /* Is it a leading whitespace? */
+
+        leading_blank = IS_BLANK(parser->buffer);
+
+        /* Consume the current line. */
+
+        while (!IS_BREAKZ(parser->buffer)) {
+            if (!READ(parser, string)) goto error;
+            if (!CACHE(parser, 1)) goto error;
+        }
+
+        /* Consume the line break. */
+
+        if (!CACHE(parser, 2)) goto error;
+
+        if (!READ_LINE(parser, leading_break)) goto error;
+
+        /* Eat the following indentation spaces and line breaks. */
+
+        if (!yaml_parser_scan_block_scalar_breaks(parser,
+                    &indent, &trailing_breaks, start_mark, &end_mark)) goto error;
+    }
+
+    /* Chomp the tail. */
+
+    if (chomping != -1) {
+        if (!JOIN(parser, string, leading_break)) goto error;
+    }
+    if (chomping == 1) {
+        if (!JOIN(parser, string, trailing_breaks)) goto error;
+    }
+
+    /* Create a token. */
+
+    SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
+            literal ? YAML_LITERAL_SCALAR_STYLE : YAML_FOLDED_SCALAR_STYLE,
+            start_mark, end_mark);
+
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+
+    return 0;
+}
+
+/*
+ * Scan indentation spaces and line breaks for a block scalar.  Determine the
+ * indentation level if needed.
+ */
+
+static int
+yaml_parser_scan_block_scalar_breaks(yaml_parser_t *parser,
+        int *indent, yaml_string_t *breaks,
+        yaml_mark_t start_mark, yaml_mark_t *end_mark)
+{
+    int max_indent = 0;
+
+    *end_mark = parser->mark;
+
+    /* Eat the indentation spaces and line breaks. */
+
+    while (1)
+    {
+        /* Eat the indentation spaces. */
+
+        if (!CACHE(parser, 1)) return 0;
+
+        while ((!*indent || (int)parser->mark.column < *indent)
+                && IS_SPACE(parser->buffer)) {
+            SKIP(parser);
+            if (!CACHE(parser, 1)) return 0;
+        }
+
+        if ((int)parser->mark.column > max_indent)
+            max_indent = (int)parser->mark.column;
+
+        /* Check for a tab character messing the indentation. */
+
+        if ((!*indent || (int)parser->mark.column < *indent)
+                && IS_TAB(parser->buffer)) {
+            return yaml_parser_set_scanner_error(parser, "while scanning a block scalar",
+                    start_mark, "found a tab character where an indentation space is expected");
+        }
+
+        /* Have we found a non-empty line? */
+
+        if (!IS_BREAK(parser->buffer)) break;
+
+        /* Consume the line break. */
+
+        if (!CACHE(parser, 2)) return 0;
+        if (!READ_LINE(parser, *breaks)) return 0;
+        *end_mark = parser->mark;
+    }
+
+    /* Determine the indentation level if needed. */
+
+    if (!*indent) {
+        *indent = max_indent;
+        if (*indent < parser->indent + 1)
+            *indent = parser->indent + 1;
+        if (*indent < 1)
+            *indent = 1;
+    }
+
+   return 1;
+}
+
+/*
+ * Scan a quoted scalar.
+ */
+
+static int
+yaml_parser_scan_flow_scalar(yaml_parser_t *parser, yaml_token_t *token,
+        int single)
+{
+    yaml_mark_t start_mark;
+    yaml_mark_t end_mark;
+    yaml_string_t string = NULL_STRING;
+    yaml_string_t leading_break = NULL_STRING;
+    yaml_string_t trailing_breaks = NULL_STRING;
+    yaml_string_t whitespaces = NULL_STRING;
+    int leading_blanks;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, whitespaces, INITIAL_STRING_SIZE)) goto error;
+
+    /* Eat the left quote. */
+
+    start_mark = parser->mark;
+
+    SKIP(parser);
+
+    /* Consume the content of the quoted scalar. */
+
+    while (1)
+    {
+        /* Check that there are no document indicators at the beginning of the line. */
+
+        if (!CACHE(parser, 4)) goto error;
+
+        if (parser->mark.column == 0 &&
+            ((CHECK_AT(parser->buffer, '-', 0) &&
+              CHECK_AT(parser->buffer, '-', 1) &&
+              CHECK_AT(parser->buffer, '-', 2)) ||
+             (CHECK_AT(parser->buffer, '.', 0) &&
+              CHECK_AT(parser->buffer, '.', 1) &&
+              CHECK_AT(parser->buffer, '.', 2))) &&
+            IS_BLANKZ_AT(parser->buffer, 3))
+        {
+            yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
+                    start_mark, "found unexpected document indicator");
+            goto error;
+        }
+
+        /* Check for EOF. */
+
+        if (IS_Z(parser->buffer)) {
+            yaml_parser_set_scanner_error(parser, "while scanning a quoted scalar",
+                    start_mark, "found unexpected end of stream");
+            goto error;
+        }
+
+        /* Consume non-blank characters. */
+
+        if (!CACHE(parser, 2)) goto error;
+
+        leading_blanks = 0;
+
+        while (!IS_BLANKZ(parser->buffer))
+        {
+            /* Check for an escaped single quote. */
+
+            if (single && CHECK_AT(parser->buffer, '\'', 0)
+                    && CHECK_AT(parser->buffer, '\'', 1))
+            {
+                if (!STRING_EXTEND(parser, string)) goto error;
+                *(string.pointer++) = '\'';
+                SKIP(parser);
+                SKIP(parser);
+            }
+
+            /* Check for the right quote. */
+
+            else if (CHECK(parser->buffer, single ? '\'' : '"'))
+            {
+                break;
+            }
+
+            /* Check for an escaped line break. */
+
+            else if (!single && CHECK(parser->buffer, '\\')
+                    && IS_BREAK_AT(parser->buffer, 1))
+            {
+                if (!CACHE(parser, 3)) goto error;
+                SKIP(parser);
+                SKIP_LINE(parser);
+                leading_blanks = 1;
+                break;
+            }
+
+            /* Check for an escape sequence. */
+
+            else if (!single && CHECK(parser->buffer, '\\'))
+            {
+                size_t code_length = 0;
+
+                if (!STRING_EXTEND(parser, string)) goto error;
+
+                /* Check the escape character. */
+
+                switch (parser->buffer.pointer[1])
+                {
+                    case '0':
+                        *(string.pointer++) = '\0';
+                        break;
+
+                    case 'a':
+                        *(string.pointer++) = '\x07';
+                        break;
+
+                    case 'b':
+                        *(string.pointer++) = '\x08';
+                        break;
+
+                    case 't':
+                    case '\t':
+                        *(string.pointer++) = '\x09';
+                        break;
+
+                    case 'n':
+                        *(string.pointer++) = '\x0A';
+                        break;
+
+                    case 'v':
+                        *(string.pointer++) = '\x0B';
+                        break;
+
+                    case 'f':
+                        *(string.pointer++) = '\x0C';
+                        break;
+
+                    case 'r':
+                        *(string.pointer++) = '\x0D';
+                        break;
+
+                    case 'e':
+                        *(string.pointer++) = '\x1B';
+                        break;
+
+                    case ' ':
+                        *(string.pointer++) = '\x20';
+                        break;
+
+                    case '"':
+                        *(string.pointer++) = '"';
+                        break;
+
+                    case '/':
+                        *(string.pointer++) = '/';
+                        break;
+
+                    case '\\':
+                        *(string.pointer++) = '\\';
+                        break;
+
+                    case 'N':   /* NEL (#x85) */
+                        *(string.pointer++) = '\xC2';
+                        *(string.pointer++) = '\x85';
+                        break;
+
+                    case '_':   /* #xA0 */
+                        *(string.pointer++) = '\xC2';
+                        *(string.pointer++) = '\xA0';
+                        break;
+
+                    case 'L':   /* LS (#x2028) */
+                        *(string.pointer++) = '\xE2';
+                        *(string.pointer++) = '\x80';
+                        *(string.pointer++) = '\xA8';
+                        break;
+
+                    case 'P':   /* PS (#x2029) */
+                        *(string.pointer++) = '\xE2';
+                        *(string.pointer++) = '\x80';
+                        *(string.pointer++) = '\xA9';
+                        break;
+
+                    case 'x':
+                        code_length = 2;
+                        break;
+
+                    case 'u':
+                        code_length = 4;
+                        break;
+
+                    case 'U':
+                        code_length = 8;
+                        break;
+
+                    default:
+                        yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
+                                start_mark, "found unknown escape character");
+                        goto error;
+                }
+
+                SKIP(parser);
+                SKIP(parser);
+
+                /* Consume an arbitrary escape code. */
+
+                if (code_length)
+                {
+                    unsigned int value = 0;
+                    size_t k;
+
+                    /* Scan the character value. */
+
+                    if (!CACHE(parser, code_length)) goto error;
+
+                    for (k = 0; k < code_length; k ++) {
+                        if (!IS_HEX_AT(parser->buffer, k)) {
+                            yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
+                                    start_mark, "did not find expected hexdecimal number");
+                            goto error;
+                        }
+                        value = (value << 4) + AS_HEX_AT(parser->buffer, k);
+                    }
+
+                    /* Check the value and write the character. */
+
+                    if ((value >= 0xD800 && value <= 0xDFFF) || value > 0x10FFFF) {
+                        yaml_parser_set_scanner_error(parser, "while parsing a quoted scalar",
+                                start_mark, "found invalid Unicode character escape code");
+                        goto error;
+                    }
+
+                    if (value <= 0x7F) {
+                        *(string.pointer++) = value;
+                    }
+                    else if (value <= 0x7FF) {
+                        *(string.pointer++) = 0xC0 + (value >> 6);
+                        *(string.pointer++) = 0x80 + (value & 0x3F);
+                    }
+                    else if (value <= 0xFFFF) {
+                        *(string.pointer++) = 0xE0 + (value >> 12);
+                        *(string.pointer++) = 0x80 + ((value >> 6) & 0x3F);
+                        *(string.pointer++) = 0x80 + (value & 0x3F);
+                    }
+                    else {
+                        *(string.pointer++) = 0xF0 + (value >> 18);
+                        *(string.pointer++) = 0x80 + ((value >> 12) & 0x3F);
+                        *(string.pointer++) = 0x80 + ((value >> 6) & 0x3F);
+                        *(string.pointer++) = 0x80 + (value & 0x3F);
+                    }
+
+                    /* Advance the pointer. */
+
+                    for (k = 0; k < code_length; k ++) {
+                        SKIP(parser);
+                    }
+                }
+            }
+
+            else
+            {
+                /* It is a non-escaped non-blank character. */
+
+                if (!READ(parser, string)) goto error;
+            }
+
+            if (!CACHE(parser, 2)) goto error;
+        }
+
+        /* Check if we are at the end of the scalar. */
+
+        /* Fix for crash unitialized value crash
+         * Credit for the bug and input is to OSS Fuzz
+         * Credit for the fix to Alex Gaynor
+         */
+        if (!CACHE(parser, 1)) goto error;
+        if (CHECK(parser->buffer, single ? '\'' : '"'))
+            break;
+
+        /* Consume blank characters. */
+
+        if (!CACHE(parser, 1)) goto error;
+
+        while (IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer))
+        {
+            if (IS_BLANK(parser->buffer))
+            {
+                /* Consume a space or a tab character. */
+
+                if (!leading_blanks) {
+                    if (!READ(parser, whitespaces)) goto error;
+                }
+                else {
+                    SKIP(parser);
+                }
+            }
+            else
+            {
+                if (!CACHE(parser, 2)) goto error;
+
+                /* Check if it is a first line break. */
+
+                if (!leading_blanks)
+                {
+                    CLEAR(parser, whitespaces);
+                    if (!READ_LINE(parser, leading_break)) goto error;
+                    leading_blanks = 1;
+                }
+                else
+                {
+                    if (!READ_LINE(parser, trailing_breaks)) goto error;
+                }
+            }
+            if (!CACHE(parser, 1)) goto error;
+        }
+
+        /* Join the whitespaces or fold line breaks. */
+
+        if (leading_blanks)
+        {
+            /* Do we need to fold line breaks? */
+
+            if (leading_break.start[0] == '\n') {
+                if (trailing_breaks.start[0] == '\0') {
+                    if (!STRING_EXTEND(parser, string)) goto error;
+                    *(string.pointer++) = ' ';
+                }
+                else {
+                    if (!JOIN(parser, string, trailing_breaks)) goto error;
+                    CLEAR(parser, trailing_breaks);
+                }
+                CLEAR(parser, leading_break);
+            }
+            else {
+                if (!JOIN(parser, string, leading_break)) goto error;
+                if (!JOIN(parser, string, trailing_breaks)) goto error;
+                CLEAR(parser, leading_break);
+                CLEAR(parser, trailing_breaks);
+            }
+        }
+        else
+        {
+            if (!JOIN(parser, string, whitespaces)) goto error;
+            CLEAR(parser, whitespaces);
+        }
+    }
+
+    /* Eat the right quote. */
+
+    SKIP(parser);
+
+    end_mark = parser->mark;
+
+    /* Create a token. */
+
+    SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
+            single ? YAML_SINGLE_QUOTED_SCALAR_STYLE : YAML_DOUBLE_QUOTED_SCALAR_STYLE,
+            start_mark, end_mark);
+
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 0;
+}
+
+/*
+ * Scan a plain scalar.
+ */
+
+static int
+yaml_parser_scan_plain_scalar(yaml_parser_t *parser, yaml_token_t *token)
+{
+    yaml_mark_t start_mark;
+    yaml_mark_t end_mark;
+    yaml_string_t string = NULL_STRING;
+    yaml_string_t leading_break = NULL_STRING;
+    yaml_string_t trailing_breaks = NULL_STRING;
+    yaml_string_t whitespaces = NULL_STRING;
+    int leading_blanks = 0;
+    int indent = parser->indent+1;
+
+    if (!STRING_INIT(parser, string, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, leading_break, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, trailing_breaks, INITIAL_STRING_SIZE)) goto error;
+    if (!STRING_INIT(parser, whitespaces, INITIAL_STRING_SIZE)) goto error;
+
+    start_mark = end_mark = parser->mark;
+
+    /* Consume the content of the plain scalar. */
+
+    while (1)
+    {
+        /* Check for a document indicator. */
+
+        if (!CACHE(parser, 4)) goto error;
+
+        if (parser->mark.column == 0 &&
+            ((CHECK_AT(parser->buffer, '-', 0) &&
+              CHECK_AT(parser->buffer, '-', 1) &&
+              CHECK_AT(parser->buffer, '-', 2)) ||
+             (CHECK_AT(parser->buffer, '.', 0) &&
+              CHECK_AT(parser->buffer, '.', 1) &&
+              CHECK_AT(parser->buffer, '.', 2))) &&
+            IS_BLANKZ_AT(parser->buffer, 3)) break;
+
+        /* Check for a comment. */
+
+        if (CHECK(parser->buffer, '#'))
+            break;
+
+        /* Consume non-blank characters. */
+
+        while (!IS_BLANKZ(parser->buffer))
+        {
+            /* Check for "x:" + one of ',?[]{}' in the flow context. TODO: Fix the test "spec-08-13".
+             * This is not completely according to the spec
+             * See http://yaml.org/spec/1.1/#id907281 9.1.3. Plain
+             */
+
+            if (parser->flow_level
+                    && CHECK(parser->buffer, ':')
+                    && (
+                        CHECK_AT(parser->buffer, ',', 1)
+                        || CHECK_AT(parser->buffer, '?', 1)
+                        || CHECK_AT(parser->buffer, '[', 1)
+                        || CHECK_AT(parser->buffer, ']', 1)
+                        || CHECK_AT(parser->buffer, '{', 1)
+                        || CHECK_AT(parser->buffer, '}', 1)
+                    )
+                    ) {
+                yaml_parser_set_scanner_error(parser, "while scanning a plain scalar",
+                        start_mark, "found unexpected ':'");
+                goto error;
+            }
+
+            /* Check for indicators that may end a plain scalar. */
+
+            if ((CHECK(parser->buffer, ':') && IS_BLANKZ_AT(parser->buffer, 1))
+                    || (parser->flow_level &&
+                        (CHECK(parser->buffer, ',')
+                         || CHECK(parser->buffer, '[')
+                         || CHECK(parser->buffer, ']') || CHECK(parser->buffer, '{')
+                         || CHECK(parser->buffer, '}'))))
+                break;
+
+            /* Check if we need to join whitespaces and breaks. */
+
+            if (leading_blanks || whitespaces.start != whitespaces.pointer)
+            {
+                if (leading_blanks)
+                {
+                    /* Do we need to fold line breaks? */
+
+                    if (leading_break.start[0] == '\n') {
+                        if (trailing_breaks.start[0] == '\0') {
+                            if (!STRING_EXTEND(parser, string)) goto error;
+                            *(string.pointer++) = ' ';
+                        }
+                        else {
+                            if (!JOIN(parser, string, trailing_breaks)) goto error;
+                            CLEAR(parser, trailing_breaks);
+                        }
+                        CLEAR(parser, leading_break);
+                    }
+                    else {
+                        if (!JOIN(parser, string, leading_break)) goto error;
+                        if (!JOIN(parser, string, trailing_breaks)) goto error;
+                        CLEAR(parser, leading_break);
+                        CLEAR(parser, trailing_breaks);
+                    }
+
+                    leading_blanks = 0;
+                }
+                else
+                {
+                    if (!JOIN(parser, string, whitespaces)) goto error;
+                    CLEAR(parser, whitespaces);
+                }
+            }
+
+            /* Copy the character. */
+
+            if (!READ(parser, string)) goto error;
+
+            end_mark = parser->mark;
+
+            if (!CACHE(parser, 2)) goto error;
+        }
+
+        /* Is it the end? */
+
+        if (!(IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer)))
+            break;
+
+        /* Consume blank characters. */
+
+        if (!CACHE(parser, 1)) goto error;
+
+        while (IS_BLANK(parser->buffer) || IS_BREAK(parser->buffer))
+        {
+            if (IS_BLANK(parser->buffer))
+            {
+                /* Check for tab characters that abuse indentation. */
+
+                if (leading_blanks && (int)parser->mark.column < indent
+                        && IS_TAB(parser->buffer)) {
+                    yaml_parser_set_scanner_error(parser, "while scanning a plain scalar",
+                            start_mark, "found a tab character that violates indentation");
+                    goto error;
+                }
+
+                /* Consume a space or a tab character. */
+
+                if (!leading_blanks) {
+                    if (!READ(parser, whitespaces)) goto error;
+                }
+                else {
+                    SKIP(parser);
+                }
+            }
+            else
+            {
+                if (!CACHE(parser, 2)) goto error;
+
+                /* Check if it is a first line break. */
+
+                if (!leading_blanks)
+                {
+                    CLEAR(parser, whitespaces);
+                    if (!READ_LINE(parser, leading_break)) goto error;
+                    leading_blanks = 1;
+                }
+                else
+                {
+                    if (!READ_LINE(parser, trailing_breaks)) goto error;
+                }
+            }
+            if (!CACHE(parser, 1)) goto error;
+        }
+
+        /* Check indentation level. */
+
+        if (!parser->flow_level && (int)parser->mark.column < indent)
+            break;
+    }
+
+    /* Create a token. */
+
+    SCALAR_TOKEN_INIT(*token, string.start, string.pointer-string.start,
+            YAML_PLAIN_SCALAR_STYLE, start_mark, end_mark);
+
+    /* Note that we change the 'simple_key_allowed' flag. */
+
+    if (leading_blanks) {
+        parser->simple_key_allowed = 1;
+    }
+
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 1;
+
+error:
+    STRING_DEL(parser, string);
+    STRING_DEL(parser, leading_break);
+    STRING_DEL(parser, trailing_breaks);
+    STRING_DEL(parser, whitespaces);
+
+    return 0;
+}
diff --git a/contrib/libs/yaml/src/writer.c b/contrib/libs/yaml/src/writer.c
new file mode 100644
index 0000000000..5d57f392f1
--- /dev/null
+++ b/contrib/libs/yaml/src/writer.c
@@ -0,0 +1,141 @@
+
+#include "yaml_private.h"
+
+/*
+ * Declarations.
+ */
+
+static int
+yaml_emitter_set_writer_error(yaml_emitter_t *emitter, const char *problem);
+
+YAML_DECLARE(int)
+yaml_emitter_flush(yaml_emitter_t *emitter);
+
+/*
+ * Set the writer error and return 0.
+ */
+
+static int
+yaml_emitter_set_writer_error(yaml_emitter_t *emitter, const char *problem)
+{
+    emitter->error = YAML_WRITER_ERROR;
+    emitter->problem = problem;
+
+    return 0;
+}
+
+/*
+ * Flush the output buffer.
+ */
+
+YAML_DECLARE(int)
+yaml_emitter_flush(yaml_emitter_t *emitter)
+{
+    int low, high;
+
+    assert(emitter);    /* Non-NULL emitter object is expected. */
+    assert(emitter->write_handler); /* Write handler must be set. */
+    assert(emitter->encoding);  /* Output encoding must be set. */
+
+    emitter->buffer.last = emitter->buffer.pointer;
+    emitter->buffer.pointer = emitter->buffer.start;
+
+    /* Check if the buffer is empty. */
+
+    if (emitter->buffer.start == emitter->buffer.last) {
+        return 1;
+    }
+
+    /* If the output encoding is UTF-8, we don't need to recode the buffer. */
+
+    if (emitter->encoding == YAML_UTF8_ENCODING)
+    {
+        if (emitter->write_handler(emitter->write_handler_data,
+                    emitter->buffer.start,
+                    emitter->buffer.last - emitter->buffer.start)) {
+            emitter->buffer.last = emitter->buffer.start;
+            emitter->buffer.pointer = emitter->buffer.start;
+            return 1;
+        }
+        else {
+            return yaml_emitter_set_writer_error(emitter, "write error");
+        }
+    }
+
+    /* Recode the buffer into the raw buffer. */
+
+    low = (emitter->encoding == YAML_UTF16LE_ENCODING ? 0 : 1);
+    high = (emitter->encoding == YAML_UTF16LE_ENCODING ? 1 : 0);
+
+    while (emitter->buffer.pointer != emitter->buffer.last)
+    {
+        unsigned char octet;
+        unsigned int width;
+        unsigned int value;
+        size_t k;
+
+        /*
+         * See the "reader.c" code for more details on UTF-8 encoding.  Note
+         * that we assume that the buffer contains a valid UTF-8 sequence.
+         */
+
+        /* Read the next UTF-8 character. */
+
+        octet = emitter->buffer.pointer[0];
+
+        width = (octet & 0x80) == 0x00 ? 1 :
+                (octet & 0xE0) == 0xC0 ? 2 :
+                (octet & 0xF0) == 0xE0 ? 3 :
+                (octet & 0xF8) == 0xF0 ? 4 : 0;
+
+        value = (octet & 0x80) == 0x00 ? octet & 0x7F :
+                (octet & 0xE0) == 0xC0 ? octet & 0x1F :
+                (octet & 0xF0) == 0xE0 ? octet & 0x0F :
+                (octet & 0xF8) == 0xF0 ? octet & 0x07 : 0;
+
+        for (k = 1; k < width; k ++) {
+            octet = emitter->buffer.pointer[k];
+            value = (value << 6) + (octet & 0x3F);
+        }
+
+        emitter->buffer.pointer += width;
+
+        /* Write the character. */
+
+        if (value < 0x10000)
+        {
+            emitter->raw_buffer.last[high] = value >> 8;
+            emitter->raw_buffer.last[low] = value & 0xFF;
+
+            emitter->raw_buffer.last += 2;
+        }
+        else
+        {
+            /* Write the character using a surrogate pair (check "reader.c"). */
+
+            value -= 0x10000;
+            emitter->raw_buffer.last[high] = 0xD8 + (value >> 18);
+            emitter->raw_buffer.last[low] = (value >> 10) & 0xFF;
+            emitter->raw_buffer.last[high+2] = 0xDC + ((value >> 8) & 0xFF);
+            emitter->raw_buffer.last[low+2] = value & 0xFF;
+
+            emitter->raw_buffer.last += 4;
+        }
+    }
+
+    /* Write the raw buffer. */
+
+    if (emitter->write_handler(emitter->write_handler_data,
+                emitter->raw_buffer.start,
+                emitter->raw_buffer.last - emitter->raw_buffer.start)) {
+        emitter->buffer.last = emitter->buffer.start;
+        emitter->buffer.pointer = emitter->buffer.start;
+        emitter->raw_buffer.last = emitter->raw_buffer.start;
+        emitter->raw_buffer.pointer = emitter->raw_buffer.start;
+        return 1;
+    }
+    else {
+        return yaml_emitter_set_writer_error(emitter, "write error");
+    }
+}
+
diff --git a/contrib/libs/yaml/src/yaml_private.h b/contrib/libs/yaml/src/yaml_private.h
new file mode 100644
index 0000000000..b3351c4165
--- /dev/null
+++ b/contrib/libs/yaml/src/yaml_private.h
@@ -0,0 +1,684 @@
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <yaml.h>
+
+#include <assert.h>
+#include <limits.h>
+#include <stddef.h>
+
+/*
+ * Memory management.
+ */
+
+YAML_DECLARE(void *)
+yaml_malloc(size_t size);
+
+YAML_DECLARE(void *)
+yaml_realloc(void *ptr, size_t size);
+
+YAML_DECLARE(void)
+yaml_free(void *ptr);
+
+YAML_DECLARE(yaml_char_t *)
+yaml_strdup(const yaml_char_t *);
+
+/*
+ * Reader: Ensure that the buffer contains at least `length` characters.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_update_buffer(yaml_parser_t *parser, size_t length);
+
+/*
+ * Scanner: Ensure that the token stack contains at least one token ready.
+ */
+
+YAML_DECLARE(int)
+yaml_parser_fetch_more_tokens(yaml_parser_t *parser);
+
+/*
+ * The size of the input raw buffer.
+ */
+
+#define INPUT_RAW_BUFFER_SIZE   16384
+
+/*
+ * The size of the input buffer.
+ *
+ * It should be possible to decode the whole raw buffer.
+ */
+
+#define INPUT_BUFFER_SIZE       (INPUT_RAW_BUFFER_SIZE*3)
+
+/*
+ * The size of the output buffer.
+ */
+
+#define OUTPUT_BUFFER_SIZE      16384
+
+/*
+ * The size of the output raw buffer.
+ *
+ * It should be possible to encode the whole output buffer.
+ */
+
+#define OUTPUT_RAW_BUFFER_SIZE  (OUTPUT_BUFFER_SIZE*2+2)
+
+/*
+ * The maximum size of a YAML input file.
+ * This used to be PTRDIFF_MAX, but that's not entirely portable
+ * because stdint.h isn't available on all platforms.
+ * It is not entirely clear why this isn't the maximum value
+ * that can fit into the parser->offset field.
+ */
+
+#define MAX_FILE_SIZE (~(size_t)0 / 2)
+
+
+/*
+ * The size of other stacks and queues.
+ */
+
+#define INITIAL_STACK_SIZE  16
+#define INITIAL_QUEUE_SIZE  16
+#define INITIAL_STRING_SIZE 16
+
+/*
+ * Buffer management.
+ */
+
+#define BUFFER_INIT(context,buffer,size)                                        \
+  (((buffer).start = (yaml_char_t *)yaml_malloc(size)) ?                        \
+        ((buffer).last = (buffer).pointer = (buffer).start,                     \
+         (buffer).end = (buffer).start+(size),                                  \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define BUFFER_DEL(context,buffer)                                              \
+    (yaml_free((buffer).start),                                                 \
+     (buffer).start = (buffer).pointer = (buffer).end = 0)
+
+/*
+ * String management.
+ */
+
+typedef struct {
+    yaml_char_t *start;
+    yaml_char_t *end;
+    yaml_char_t *pointer;
+} yaml_string_t;
+
+YAML_DECLARE(int)
+yaml_string_extend(yaml_char_t **start,
+        yaml_char_t **pointer, yaml_char_t **end);
+
+YAML_DECLARE(int)
+yaml_string_join(
+        yaml_char_t **a_start, yaml_char_t **a_pointer, yaml_char_t **a_end,
+        yaml_char_t **b_start, yaml_char_t **b_pointer, yaml_char_t **b_end);
+
+#define NULL_STRING { NULL, NULL, NULL }
+
+#define STRING(string,length)   { (string), (string)+(length), (string) }
+
+#define STRING_ASSIGN(value,string,length)                                      \
+    ((value).start = (string),                                                  \
+     (value).end = (string)+(length),                                           \
+     (value).pointer = (string))
+
+#define STRING_INIT(context,string,size)                                        \
+    (((string).start = YAML_MALLOC(size)) ?                                     \
+        ((string).pointer = (string).start,                                     \
+         (string).end = (string).start+(size),                                  \
+         memset((string).start, 0, (size)),                                     \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define STRING_DEL(context,string)                                              \
+    (yaml_free((string).start),                                                 \
+     (string).start = (string).pointer = (string).end = 0)
+
+#define STRING_EXTEND(context,string)                                           \
+    ((((string).pointer+5 < (string).end)                                       \
+        || yaml_string_extend(&(string).start,                                  \
+            &(string).pointer, &(string).end)) ?                                \
+         1 :                                                                    \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define CLEAR(context,string)                                                   \
+    ((string).pointer = (string).start,                                         \
+     memset((string).start, 0, (string).end-(string).start))
+
+#define JOIN(context,string_a,string_b)                                         \
+    ((yaml_string_join(&(string_a).start, &(string_a).pointer,                  \
+                       &(string_a).end, &(string_b).start,                      \
+                       &(string_b).pointer, &(string_b).end)) ?                 \
+        ((string_b).pointer = (string_b).start,                                 \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+/*
+ * String check operations.
+ */
+
+/*
+ * Check the octet at the specified position.
+ */
+
+#define CHECK_AT(string,octet,offset)                   \
+    ((string).pointer[offset] == (yaml_char_t)(octet))
+
+/*
+ * Check the current octet in the buffer.
+ */
+
+#define CHECK(string,octet) (CHECK_AT((string),(octet),0))
+
+/*
+ * Check if the character at the specified position is an alphabetical
+ * character, a digit, '_', or '-'.
+ */
+
+#define IS_ALPHA_AT(string,offset)                                              \
+     (((string).pointer[offset] >= (yaml_char_t) '0' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) '9') ||                        \
+      ((string).pointer[offset] >= (yaml_char_t) 'A' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) 'Z') ||                        \
+      ((string).pointer[offset] >= (yaml_char_t) 'a' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) 'z') ||                        \
+      (string).pointer[offset] == '_' ||                                        \
+      (string).pointer[offset] == '-')
+
+#define IS_ALPHA(string)    IS_ALPHA_AT((string),0)
+
+/*
+ * Check if the character at the specified position is a digit.
+ */
+
+#define IS_DIGIT_AT(string,offset)                                              \
+     (((string).pointer[offset] >= (yaml_char_t) '0' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) '9'))
+
+#define IS_DIGIT(string)    IS_DIGIT_AT((string),0)
+
+/*
+ * Get the value of a digit.
+ */
+
+#define AS_DIGIT_AT(string,offset)                                              \
+     ((string).pointer[offset] - (yaml_char_t) '0')
+
+#define AS_DIGIT(string)    AS_DIGIT_AT((string),0)
+
+/*
+ * Check if the character at the specified position is a hex-digit.
+ */
+
+#define IS_HEX_AT(string,offset)                                                \
+     (((string).pointer[offset] >= (yaml_char_t) '0' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) '9') ||                        \
+      ((string).pointer[offset] >= (yaml_char_t) 'A' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) 'F') ||                        \
+      ((string).pointer[offset] >= (yaml_char_t) 'a' &&                         \
+       (string).pointer[offset] <= (yaml_char_t) 'f'))
+
+#define IS_HEX(string)    IS_HEX_AT((string),0)
+
+/*
+ * Get the value of a hex-digit.
+ */
+
+#define AS_HEX_AT(string,offset)                                                \
+      (((string).pointer[offset] >= (yaml_char_t) 'A' &&                        \
+        (string).pointer[offset] <= (yaml_char_t) 'F') ?                        \
+       ((string).pointer[offset] - (yaml_char_t) 'A' + 10) :                    \
+       ((string).pointer[offset] >= (yaml_char_t) 'a' &&                        \
+        (string).pointer[offset] <= (yaml_char_t) 'f') ?                        \
+       ((string).pointer[offset] - (yaml_char_t) 'a' + 10) :                    \
+       ((string).pointer[offset] - (yaml_char_t) '0'))
+
+#define AS_HEX(string)  AS_HEX_AT((string),0)
+
+/*
+ * Check if the character is ASCII.
+ */
+
+#define IS_ASCII_AT(string,offset)                                              \
+    ((string).pointer[offset] <= (yaml_char_t) '\x7F')
+
+#define IS_ASCII(string)    IS_ASCII_AT((string),0)
+
+/*
+ * Check if the character can be printed unescaped.
+ */
+
+#define IS_PRINTABLE_AT(string,offset)                                          \
+    (((string).pointer[offset] == 0x0A)         /* . == #x0A */                 \
+     || ((string).pointer[offset] >= 0x20       /* #x20 <= . <= #x7E */         \
+         && (string).pointer[offset] <= 0x7E)                                   \
+     || ((string).pointer[offset] == 0xC2       /* #0xA0 <= . <= #xD7FF */      \
+         && (string).pointer[offset+1] >= 0xA0)                                 \
+     || ((string).pointer[offset] > 0xC2                                        \
+         && (string).pointer[offset] < 0xED)                                    \
+     || ((string).pointer[offset] == 0xED                                       \
+         && (string).pointer[offset+1] < 0xA0)                                  \
+     || ((string).pointer[offset] == 0xEE)                                      \
+     || ((string).pointer[offset] == 0xEF      /* #xE000 <= . <= #xFFFD */      \
+         && !((string).pointer[offset+1] == 0xBB        /* && . != #xFEFF */    \
+             && (string).pointer[offset+2] == 0xBF)                             \
+         && !((string).pointer[offset+1] == 0xBF                                \
+             && ((string).pointer[offset+2] == 0xBE                             \
+                 || (string).pointer[offset+2] == 0xBF))))
+
+#define IS_PRINTABLE(string)    IS_PRINTABLE_AT((string),0)
+
+/*
+ * Check if the character at the specified position is NUL.
+ */
+
+#define IS_Z_AT(string,offset)    CHECK_AT((string),'\0',(offset))
+
+#define IS_Z(string)    IS_Z_AT((string),0)
+
+/*
+ * Check if the character at the specified position is BOM.
+ */
+
+#define IS_BOM_AT(string,offset)                                                \
+     (CHECK_AT((string),'\xEF',(offset))                                        \
+      && CHECK_AT((string),'\xBB',(offset)+1)                                   \
+      && CHECK_AT((string),'\xBF',(offset)+2))  /* BOM (#xFEFF) */
+
+#define IS_BOM(string)  IS_BOM_AT(string,0)
+
+/*
+ * Check if the character at the specified position is space.
+ */
+
+#define IS_SPACE_AT(string,offset)  CHECK_AT((string),' ',(offset))
+
+#define IS_SPACE(string)    IS_SPACE_AT((string),0)
+
+/*
+ * Check if the character at the specified position is tab.
+ */
+
+#define IS_TAB_AT(string,offset)    CHECK_AT((string),'\t',(offset))
+
+#define IS_TAB(string)  IS_TAB_AT((string),0)
+
+/*
+ * Check if the character at the specified position is blank (space or tab).
+ */
+
+#define IS_BLANK_AT(string,offset)                                              \
+    (IS_SPACE_AT((string),(offset)) || IS_TAB_AT((string),(offset)))
+
+#define IS_BLANK(string)    IS_BLANK_AT((string),0)
+
+/*
+ * Check if the character at the specified position is a line break.
+ */
+
+#define IS_BREAK_AT(string,offset)                                              \
+    (CHECK_AT((string),'\r',(offset))               /* CR (#xD)*/               \
+     || CHECK_AT((string),'\n',(offset))            /* LF (#xA) */              \
+     || (CHECK_AT((string),'\xC2',(offset))                                     \
+         && CHECK_AT((string),'\x85',(offset)+1))   /* NEL (#x85) */            \
+     || (CHECK_AT((string),'\xE2',(offset))                                     \
+         && CHECK_AT((string),'\x80',(offset)+1)                                \
+         && CHECK_AT((string),'\xA8',(offset)+2))   /* LS (#x2028) */           \
+     || (CHECK_AT((string),'\xE2',(offset))                                     \
+         && CHECK_AT((string),'\x80',(offset)+1)                                \
+         && CHECK_AT((string),'\xA9',(offset)+2)))  /* PS (#x2029) */
+
+#define IS_BREAK(string)    IS_BREAK_AT((string),0)
+
+#define IS_CRLF_AT(string,offset)                                               \
+     (CHECK_AT((string),'\r',(offset)) && CHECK_AT((string),'\n',(offset)+1))
+
+#define IS_CRLF(string) IS_CRLF_AT((string),0)
+
+/*
+ * Check if the character is a line break or NUL.
+ */
+
+#define IS_BREAKZ_AT(string,offset)                                             \
+    (IS_BREAK_AT((string),(offset)) || IS_Z_AT((string),(offset)))
+
+#define IS_BREAKZ(string)   IS_BREAKZ_AT((string),0)
+
+/*
+ * Check if the character is a line break, space, or NUL.
+ */
+
+#define IS_SPACEZ_AT(string,offset)                                             \
+    (IS_SPACE_AT((string),(offset)) || IS_BREAKZ_AT((string),(offset)))
+
+#define IS_SPACEZ(string)   IS_SPACEZ_AT((string),0)
+
+/*
+ * Check if the character is a line break, space, tab, or NUL.
+ */
+
+#define IS_BLANKZ_AT(string,offset)                                             \
+    (IS_BLANK_AT((string),(offset)) || IS_BREAKZ_AT((string),(offset)))
+
+#define IS_BLANKZ(string)   IS_BLANKZ_AT((string),0)
+
+/*
+ * Determine the width of the character.
+ */
+
+#define WIDTH_AT(string,offset)                                                 \
+     (((string).pointer[offset] & 0x80) == 0x00 ? 1 :                           \
+      ((string).pointer[offset] & 0xE0) == 0xC0 ? 2 :                           \
+      ((string).pointer[offset] & 0xF0) == 0xE0 ? 3 :                           \
+      ((string).pointer[offset] & 0xF8) == 0xF0 ? 4 : 0)
+
+#define WIDTH(string)   WIDTH_AT((string),0)
+
+/*
+ * Move the string pointer to the next character.
+ */
+
+#define MOVE(string)    ((string).pointer += WIDTH((string)))
+
+/*
+ * Copy a character and move the pointers of both strings.
+ */
+
+#define COPY(string_a,string_b)                                                 \
+    ((*(string_b).pointer & 0x80) == 0x00 ?                                     \
+     (*((string_a).pointer++) = *((string_b).pointer++)) :                      \
+     (*(string_b).pointer & 0xE0) == 0xC0 ?                                     \
+     (*((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++)) :                      \
+     (*(string_b).pointer & 0xF0) == 0xE0 ?                                     \
+     (*((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++)) :                      \
+     (*(string_b).pointer & 0xF8) == 0xF0 ?                                     \
+     (*((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++),                        \
+      *((string_a).pointer++) = *((string_b).pointer++)) : 0)
+
+/*
+ * Stack and queue management.
+ */
+
+YAML_DECLARE(int)
+yaml_stack_extend(void **start, void **top, void **end);
+
+YAML_DECLARE(int)
+yaml_queue_extend(void **start, void **head, void **tail, void **end);
+
+#define STACK_INIT(context,stack,type)                                     \
+  (((stack).start = (type)yaml_malloc(INITIAL_STACK_SIZE*sizeof(*(stack).start))) ? \
+        ((stack).top = (stack).start,                                           \
+         (stack).end = (stack).start+INITIAL_STACK_SIZE,                        \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define STACK_DEL(context,stack)                                                \
+    (yaml_free((stack).start),                                                  \
+     (stack).start = (stack).top = (stack).end = 0)
+
+#define STACK_EMPTY(context,stack)                                              \
+    ((stack).start == (stack).top)
+
+#define STACK_LIMIT(context,stack,size)                                         \
+    ((stack).top - (stack).start < (size) ?                                     \
+        1 :                                                                     \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define PUSH(context,stack,value)                                               \
+    (((stack).top != (stack).end                                                \
+      || yaml_stack_extend((void **)&(stack).start,                             \
+              (void **)&(stack).top, (void **)&(stack).end)) ?                  \
+        (*((stack).top++) = value,                                              \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define POP(context,stack)                                                      \
+    (*(--(stack).top))
+
+#define QUEUE_INIT(context,queue,size,type)                                     \
+  (((queue).start = (type)yaml_malloc((size)*sizeof(*(queue).start))) ?         \
+        ((queue).head = (queue).tail = (queue).start,                           \
+         (queue).end = (queue).start+(size),                                    \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define QUEUE_DEL(context,queue)                                                \
+    (yaml_free((queue).start),                                                  \
+     (queue).start = (queue).head = (queue).tail = (queue).end = 0)
+
+#define QUEUE_EMPTY(context,queue)                                              \
+    ((queue).head == (queue).tail)
+
+#define ENQUEUE(context,queue,value)                                            \
+    (((queue).tail != (queue).end                                               \
+      || yaml_queue_extend((void **)&(queue).start, (void **)&(queue).head,     \
+            (void **)&(queue).tail, (void **)&(queue).end)) ?                   \
+        (*((queue).tail++) = value,                                             \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+#define DEQUEUE(context,queue)                                                  \
+    (*((queue).head++))
+
+#define QUEUE_INSERT(context,queue,index,value)                                 \
+    (((queue).tail != (queue).end                                               \
+      || yaml_queue_extend((void **)&(queue).start, (void **)&(queue).head,     \
+            (void **)&(queue).tail, (void **)&(queue).end)) ?                   \
+        (memmove((queue).head+(index)+1,(queue).head+(index),                   \
+            ((queue).tail-(queue).head-(index))*sizeof(*(queue).start)),        \
+         *((queue).head+(index)) = value,                                       \
+         (queue).tail++,                                                        \
+         1) :                                                                   \
+        ((context)->error = YAML_MEMORY_ERROR,                                  \
+         0))
+
+/*
+ * Token initializers.
+ */
+
+#define TOKEN_INIT(token,token_type,token_start_mark,token_end_mark)            \
+    (memset(&(token), 0, sizeof(yaml_token_t)),                                 \
+     (token).type = (token_type),                                               \
+     (token).start_mark = (token_start_mark),                                   \
+     (token).end_mark = (token_end_mark))
+
+#define STREAM_START_TOKEN_INIT(token,token_encoding,start_mark,end_mark)       \
+    (TOKEN_INIT((token),YAML_STREAM_START_TOKEN,(start_mark),(end_mark)),       \
+     (token).data.stream_start.encoding = (token_encoding))
+
+#define STREAM_END_TOKEN_INIT(token,start_mark,end_mark)                        \
+    (TOKEN_INIT((token),YAML_STREAM_END_TOKEN,(start_mark),(end_mark)))
+
+#define ALIAS_TOKEN_INIT(token,token_value,start_mark,end_mark)                 \
+    (TOKEN_INIT((token),YAML_ALIAS_TOKEN,(start_mark),(end_mark)),              \
+     (token).data.alias.value = (token_value))
+
+#define ANCHOR_TOKEN_INIT(token,token_value,start_mark,end_mark)                \
+    (TOKEN_INIT((token),YAML_ANCHOR_TOKEN,(start_mark),(end_mark)),             \
+     (token).data.anchor.value = (token_value))
+
+#define TAG_TOKEN_INIT(token,token_handle,token_suffix,start_mark,end_mark)     \
+    (TOKEN_INIT((token),YAML_TAG_TOKEN,(start_mark),(end_mark)),                \
+     (token).data.tag.handle = (token_handle),                                  \
+     (token).data.tag.suffix = (token_suffix))
+
+#define SCALAR_TOKEN_INIT(token,token_value,token_length,token_style,start_mark,end_mark)   \
+    (TOKEN_INIT((token),YAML_SCALAR_TOKEN,(start_mark),(end_mark)),             \
+     (token).data.scalar.value = (token_value),                                 \
+     (token).data.scalar.length = (token_length),                               \
+     (token).data.scalar.style = (token_style))
+
+#define VERSION_DIRECTIVE_TOKEN_INIT(token,token_major,token_minor,start_mark,end_mark)     \
+    (TOKEN_INIT((token),YAML_VERSION_DIRECTIVE_TOKEN,(start_mark),(end_mark)),  \
+     (token).data.version_directive.major = (token_major),                      \
+     (token).data.version_directive.minor = (token_minor))
+
+#define TAG_DIRECTIVE_TOKEN_INIT(token,token_handle,token_prefix,start_mark,end_mark)       \
+    (TOKEN_INIT((token),YAML_TAG_DIRECTIVE_TOKEN,(start_mark),(end_mark)),      \
+     (token).data.tag_directive.handle = (token_handle),                        \
+     (token).data.tag_directive.prefix = (token_prefix))
+
+/*
+ * Event initializers.
+ */
+
+#define EVENT_INIT(event,event_type,event_start_mark,event_end_mark)            \
+    (memset(&(event), 0, sizeof(yaml_event_t)),                                 \
+     (event).type = (event_type),                                               \
+     (event).start_mark = (event_start_mark),                                   \
+     (event).end_mark = (event_end_mark))
+
+#define STREAM_START_EVENT_INIT(event,event_encoding,start_mark,end_mark)       \
+    (EVENT_INIT((event),YAML_STREAM_START_EVENT,(start_mark),(end_mark)),       \
+     (event).data.stream_start.encoding = (event_encoding))
+
+#define STREAM_END_EVENT_INIT(event,start_mark,end_mark)                        \
+    (EVENT_INIT((event),YAML_STREAM_END_EVENT,(start_mark),(end_mark)))
+
+#define DOCUMENT_START_EVENT_INIT(event,event_version_directive,                \
+        event_tag_directives_start,event_tag_directives_end,event_implicit,start_mark,end_mark) \
+    (EVENT_INIT((event),YAML_DOCUMENT_START_EVENT,(start_mark),(end_mark)),     \
+     (event).data.document_start.version_directive = (event_version_directive), \
+     (event).data.document_start.tag_directives.start = (event_tag_directives_start),   \
+     (event).data.document_start.tag_directives.end = (event_tag_directives_end),   \
+     (event).data.document_start.implicit = (event_implicit))
+
+#define DOCUMENT_END_EVENT_INIT(event,event_implicit,start_mark,end_mark)       \
+    (EVENT_INIT((event),YAML_DOCUMENT_END_EVENT,(start_mark),(end_mark)),       \
+     (event).data.document_end.implicit = (event_implicit))
+
+#define ALIAS_EVENT_INIT(event,event_anchor,start_mark,end_mark)                \
+    (EVENT_INIT((event),YAML_ALIAS_EVENT,(start_mark),(end_mark)),              \
+     (event).data.alias.anchor = (event_anchor))
+
+#define SCALAR_EVENT_INIT(event,event_anchor,event_tag,event_value,event_length,    \
+        event_plain_implicit, event_quoted_implicit,event_style,start_mark,end_mark)    \
+    (EVENT_INIT((event),YAML_SCALAR_EVENT,(start_mark),(end_mark)),             \
+     (event).data.scalar.anchor = (event_anchor),                               \
+     (event).data.scalar.tag = (event_tag),                                     \
+     (event).data.scalar.value = (event_value),                                 \
+     (event).data.scalar.length = (event_length),                               \
+     (event).data.scalar.plain_implicit = (event_plain_implicit),               \
+     (event).data.scalar.quoted_implicit = (event_quoted_implicit),             \
+     (event).data.scalar.style = (event_style))
+
+#define SEQUENCE_START_EVENT_INIT(event,event_anchor,event_tag,                 \
+        event_implicit,event_style,start_mark,end_mark)                         \
+    (EVENT_INIT((event),YAML_SEQUENCE_START_EVENT,(start_mark),(end_mark)),     \
+     (event).data.sequence_start.anchor = (event_anchor),                       \
+     (event).data.sequence_start.tag = (event_tag),                             \
+     (event).data.sequence_start.implicit = (event_implicit),                   \
+     (event).data.sequence_start.style = (event_style))
+
+#define SEQUENCE_END_EVENT_INIT(event,start_mark,end_mark)                      \
+    (EVENT_INIT((event),YAML_SEQUENCE_END_EVENT,(start_mark),(end_mark)))
+
+#define MAPPING_START_EVENT_INIT(event,event_anchor,event_tag,                  \
+        event_implicit,event_style,start_mark,end_mark)                         \
+    (EVENT_INIT((event),YAML_MAPPING_START_EVENT,(start_mark),(end_mark)),      \
+     (event).data.mapping_start.anchor = (event_anchor),                        \
+     (event).data.mapping_start.tag = (event_tag),                              \
+     (event).data.mapping_start.implicit = (event_implicit),                    \
+     (event).data.mapping_start.style = (event_style))
+
+#define MAPPING_END_EVENT_INIT(event,start_mark,end_mark)                       \
+    (EVENT_INIT((event),YAML_MAPPING_END_EVENT,(start_mark),(end_mark)))
+
+/*
+ * Document initializer.
+ */
+
+#define DOCUMENT_INIT(document,document_nodes_start,document_nodes_end,         \
+        document_version_directive,document_tag_directives_start,               \
+        document_tag_directives_end,document_start_implicit,                    \
+        document_end_implicit,document_start_mark,document_end_mark)            \
+    (memset(&(document), 0, sizeof(yaml_document_t)),                           \
+     (document).nodes.start = (document_nodes_start),                           \
+     (document).nodes.end = (document_nodes_end),                               \
+     (document).nodes.top = (document_nodes_start),                             \
+     (document).version_directive = (document_version_directive),               \
+     (document).tag_directives.start = (document_tag_directives_start),         \
+     (document).tag_directives.end = (document_tag_directives_end),             \
+     (document).start_implicit = (document_start_implicit),                     \
+     (document).end_implicit = (document_end_implicit),                         \
+     (document).start_mark = (document_start_mark),                             \
+     (document).end_mark = (document_end_mark))
+
+/*
+ * Node initializers.
+ */
+
+#define NODE_INIT(node,node_type,node_tag,node_start_mark,node_end_mark)        \
+    (memset(&(node), 0, sizeof(yaml_node_t)),                                   \
+     (node).type = (node_type),                                                 \
+     (node).tag = (node_tag),                                                   \
+     (node).start_mark = (node_start_mark),                                     \
+     (node).end_mark = (node_end_mark))
+
+#define SCALAR_NODE_INIT(node,node_tag,node_value,node_length,                  \
+        node_style,start_mark,end_mark)                                         \
+    (NODE_INIT((node),YAML_SCALAR_NODE,(node_tag),(start_mark),(end_mark)),     \
+     (node).data.scalar.value = (node_value),                                   \
+     (node).data.scalar.length = (node_length),                                 \
+     (node).data.scalar.style = (node_style))
+
+#define SEQUENCE_NODE_INIT(node,node_tag,node_items_start,node_items_end,       \
+        node_style,start_mark,end_mark)                                         \
+    (NODE_INIT((node),YAML_SEQUENCE_NODE,(node_tag),(start_mark),(end_mark)),   \
+     (node).data.sequence.items.start = (node_items_start),                     \
+     (node).data.sequence.items.end = (node_items_end),                         \
+     (node).data.sequence.items.top = (node_items_start),                       \
+     (node).data.sequence.style = (node_style))
+
+#define MAPPING_NODE_INIT(node,node_tag,node_pairs_start,node_pairs_end,        \
+        node_style,start_mark,end_mark)                                         \
+    (NODE_INIT((node),YAML_MAPPING_NODE,(node_tag),(start_mark),(end_mark)),    \
+     (node).data.mapping.pairs.start = (node_pairs_start),                      \
+     (node).data.mapping.pairs.end = (node_pairs_end),                          \
+     (node).data.mapping.pairs.top = (node_pairs_start),                        \
+     (node).data.mapping.style = (node_style))
+
+/* Strict C compiler warning helpers */
+
+#if defined(__clang__) || defined(__GNUC__)
+#  define HASATTRIBUTE_UNUSED
+#endif
+#ifdef HASATTRIBUTE_UNUSED
+#  define __attribute__unused__             __attribute__((__unused__))
+#else
+#  define __attribute__unused__
+#endif
+
+/* Shim arguments are arguments that must be included in your function,
+ * but serve no purpose inside.  Silence compiler warnings. */
+#define SHIM(a) /*@unused@*/ a __attribute__unused__
+
+/* UNUSED_PARAM() marks a shim argument in the body to silence compiler warnings */
+#ifdef __clang__
+#  define UNUSED_PARAM(a) (void)(a);
+#else
+#  define UNUSED_PARAM(a) /*@-noeffect*/if (0) (void)(a)/*@=noeffect*/;
+#endif
+
+#define YAML_MALLOC_STATIC(type) (type*)yaml_malloc(sizeof(type))
+#define YAML_MALLOC(size)        (yaml_char_t *)yaml_malloc(size)