Library import 16 (#2433)

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1 files changed, 1680 insertions, 0 deletions

diff --git a/contrib/tools/python3/Parser/action_helpers.c b/contrib/tools/python3/Parser/action_helpers.c
new file mode 100644
index 0000000000..e68a9cac25
--- /dev/null
+++ b/contrib/tools/python3/Parser/action_helpers.c
@@ -0,0 +1,1680 @@
+#include <Python.h>
+
+#include "pegen.h"
+#include "tokenizer.h"
+#include "string_parser.h"
+#include "pycore_runtime.h"         // _PyRuntime
+
+void *
+_PyPegen_dummy_name(Parser *p, ...)
+{
+    return &_PyRuntime.parser.dummy_name;
+}
+
+/* Creates a single-element asdl_seq* that contains a */
+asdl_seq *
+_PyPegen_singleton_seq(Parser *p, void *a)
+{
+    assert(a != NULL);
+    asdl_seq *seq = (asdl_seq*)_Py_asdl_generic_seq_new(1, p->arena);
+    if (!seq) {
+        return NULL;
+    }
+    asdl_seq_SET_UNTYPED(seq, 0, a);
+    return seq;
+}
+
+/* Creates a copy of seq and prepends a to it */
+asdl_seq *
+_PyPegen_seq_insert_in_front(Parser *p, void *a, asdl_seq *seq)
+{
+    assert(a != NULL);
+    if (!seq) {
+        return _PyPegen_singleton_seq(p, a);
+    }
+
+    asdl_seq *new_seq = (asdl_seq*)_Py_asdl_generic_seq_new(asdl_seq_LEN(seq) + 1, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+
+    asdl_seq_SET_UNTYPED(new_seq, 0, a);
+    for (Py_ssize_t i = 1, l = asdl_seq_LEN(new_seq); i < l; i++) {
+        asdl_seq_SET_UNTYPED(new_seq, i, asdl_seq_GET_UNTYPED(seq, i - 1));
+    }
+    return new_seq;
+}
+
+/* Creates a copy of seq and appends a to it */
+asdl_seq *
+_PyPegen_seq_append_to_end(Parser *p, asdl_seq *seq, void *a)
+{
+    assert(a != NULL);
+    if (!seq) {
+        return _PyPegen_singleton_seq(p, a);
+    }
+
+    asdl_seq *new_seq = (asdl_seq*)_Py_asdl_generic_seq_new(asdl_seq_LEN(seq) + 1, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+
+    for (Py_ssize_t i = 0, l = asdl_seq_LEN(new_seq); i + 1 < l; i++) {
+        asdl_seq_SET_UNTYPED(new_seq, i, asdl_seq_GET_UNTYPED(seq, i));
+    }
+    asdl_seq_SET_UNTYPED(new_seq, asdl_seq_LEN(new_seq) - 1, a);
+    return new_seq;
+}
+
+static Py_ssize_t
+_get_flattened_seq_size(asdl_seq *seqs)
+{
+    Py_ssize_t size = 0;
+    for (Py_ssize_t i = 0, l = asdl_seq_LEN(seqs); i < l; i++) {
+        asdl_seq *inner_seq = asdl_seq_GET_UNTYPED(seqs, i);
+        size += asdl_seq_LEN(inner_seq);
+    }
+    return size;
+}
+
+/* Flattens an asdl_seq* of asdl_seq*s */
+asdl_seq *
+_PyPegen_seq_flatten(Parser *p, asdl_seq *seqs)
+{
+    Py_ssize_t flattened_seq_size = _get_flattened_seq_size(seqs);
+    assert(flattened_seq_size > 0);
+
+    asdl_seq *flattened_seq = (asdl_seq*)_Py_asdl_generic_seq_new(flattened_seq_size, p->arena);
+    if (!flattened_seq) {
+        return NULL;
+    }
+
+    int flattened_seq_idx = 0;
+    for (Py_ssize_t i = 0, l = asdl_seq_LEN(seqs); i < l; i++) {
+        asdl_seq *inner_seq = asdl_seq_GET_UNTYPED(seqs, i);
+        for (Py_ssize_t j = 0, li = asdl_seq_LEN(inner_seq); j < li; j++) {
+            asdl_seq_SET_UNTYPED(flattened_seq, flattened_seq_idx++, asdl_seq_GET_UNTYPED(inner_seq, j));
+        }
+    }
+    assert(flattened_seq_idx == flattened_seq_size);
+
+    return flattened_seq;
+}
+
+void *
+_PyPegen_seq_last_item(asdl_seq *seq)
+{
+    Py_ssize_t len = asdl_seq_LEN(seq);
+    return asdl_seq_GET_UNTYPED(seq, len - 1);
+}
+
+void *
+_PyPegen_seq_first_item(asdl_seq *seq)
+{
+    return asdl_seq_GET_UNTYPED(seq, 0);
+}
+
+/* Creates a new name of the form <first_name>.<second_name> */
+expr_ty
+_PyPegen_join_names_with_dot(Parser *p, expr_ty first_name, expr_ty second_name)
+{
+    assert(first_name != NULL && second_name != NULL);
+    PyObject *first_identifier = first_name->v.Name.id;
+    PyObject *second_identifier = second_name->v.Name.id;
+
+    if (PyUnicode_READY(first_identifier) == -1) {
+        return NULL;
+    }
+    if (PyUnicode_READY(second_identifier) == -1) {
+        return NULL;
+    }
+    const char *first_str = PyUnicode_AsUTF8(first_identifier);
+    if (!first_str) {
+        return NULL;
+    }
+    const char *second_str = PyUnicode_AsUTF8(second_identifier);
+    if (!second_str) {
+        return NULL;
+    }
+    Py_ssize_t len = strlen(first_str) + strlen(second_str) + 1;  // +1 for the dot
+
+    PyObject *str = PyBytes_FromStringAndSize(NULL, len);
+    if (!str) {
+        return NULL;
+    }
+
+    char *s = PyBytes_AS_STRING(str);
+    if (!s) {
+        return NULL;
+    }
+
+    strcpy(s, first_str);
+    s += strlen(first_str);
+    *s++ = '.';
+    strcpy(s, second_str);
+    s += strlen(second_str);
+    *s = '\0';
+
+    PyObject *uni = PyUnicode_DecodeUTF8(PyBytes_AS_STRING(str), PyBytes_GET_SIZE(str), NULL);
+    Py_DECREF(str);
+    if (!uni) {
+        return NULL;
+    }
+    PyUnicode_InternInPlace(&uni);
+    if (_PyArena_AddPyObject(p->arena, uni) < 0) {
+        Py_DECREF(uni);
+        return NULL;
+    }
+
+    return _PyAST_Name(uni, Load, EXTRA_EXPR(first_name, second_name));
+}
+
+/* Counts the total number of dots in seq's tokens */
+int
+_PyPegen_seq_count_dots(asdl_seq *seq)
+{
+    int number_of_dots = 0;
+    for (Py_ssize_t i = 0, l = asdl_seq_LEN(seq); i < l; i++) {
+        Token *current_expr = asdl_seq_GET_UNTYPED(seq, i);
+        switch (current_expr->type) {
+            case ELLIPSIS:
+                number_of_dots += 3;
+                break;
+            case DOT:
+                number_of_dots += 1;
+                break;
+            default:
+                Py_UNREACHABLE();
+        }
+    }
+
+    return number_of_dots;
+}
+
+/* Creates an alias with '*' as the identifier name */
+alias_ty
+_PyPegen_alias_for_star(Parser *p, int lineno, int col_offset, int end_lineno,
+                        int end_col_offset, PyArena *arena) {
+    PyObject *str = PyUnicode_InternFromString("*");
+    if (!str) {
+        return NULL;
+    }
+    if (_PyArena_AddPyObject(p->arena, str) < 0) {
+        Py_DECREF(str);
+        return NULL;
+    }
+    return _PyAST_alias(str, NULL, lineno, col_offset, end_lineno, end_col_offset, arena);
+}
+
+/* Creates a new asdl_seq* with the identifiers of all the names in seq */
+asdl_identifier_seq *
+_PyPegen_map_names_to_ids(Parser *p, asdl_expr_seq *seq)
+{
+    Py_ssize_t len = asdl_seq_LEN(seq);
+    assert(len > 0);
+
+    asdl_identifier_seq *new_seq = _Py_asdl_identifier_seq_new(len, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+    for (Py_ssize_t i = 0; i < len; i++) {
+        expr_ty e = asdl_seq_GET(seq, i);
+        asdl_seq_SET(new_seq, i, e->v.Name.id);
+    }
+    return new_seq;
+}
+
+/* Constructs a CmpopExprPair */
+CmpopExprPair *
+_PyPegen_cmpop_expr_pair(Parser *p, cmpop_ty cmpop, expr_ty expr)
+{
+    assert(expr != NULL);
+    CmpopExprPair *a = _PyArena_Malloc(p->arena, sizeof(CmpopExprPair));
+    if (!a) {
+        return NULL;
+    }
+    a->cmpop = cmpop;
+    a->expr = expr;
+    return a;
+}
+
+asdl_int_seq *
+_PyPegen_get_cmpops(Parser *p, asdl_seq *seq)
+{
+    Py_ssize_t len = asdl_seq_LEN(seq);
+    assert(len > 0);
+
+    asdl_int_seq *new_seq = _Py_asdl_int_seq_new(len, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+    for (Py_ssize_t i = 0; i < len; i++) {
+        CmpopExprPair *pair = asdl_seq_GET_UNTYPED(seq, i);
+        asdl_seq_SET(new_seq, i, pair->cmpop);
+    }
+    return new_seq;
+}
+
+asdl_expr_seq *
+_PyPegen_get_exprs(Parser *p, asdl_seq *seq)
+{
+    Py_ssize_t len = asdl_seq_LEN(seq);
+    assert(len > 0);
+
+    asdl_expr_seq *new_seq = _Py_asdl_expr_seq_new(len, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+    for (Py_ssize_t i = 0; i < len; i++) {
+        CmpopExprPair *pair = asdl_seq_GET_UNTYPED(seq, i);
+        asdl_seq_SET(new_seq, i, pair->expr);
+    }
+    return new_seq;
+}
+
+/* Creates an asdl_seq* where all the elements have been changed to have ctx as context */
+static asdl_expr_seq *
+_set_seq_context(Parser *p, asdl_expr_seq *seq, expr_context_ty ctx)
+{
+    Py_ssize_t len = asdl_seq_LEN(seq);
+    if (len == 0) {
+        return NULL;
+    }
+
+    asdl_expr_seq *new_seq = _Py_asdl_expr_seq_new(len, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+    for (Py_ssize_t i = 0; i < len; i++) {
+        expr_ty e = asdl_seq_GET(seq, i);
+        asdl_seq_SET(new_seq, i, _PyPegen_set_expr_context(p, e, ctx));
+    }
+    return new_seq;
+}
+
+static expr_ty
+_set_name_context(Parser *p, expr_ty e, expr_context_ty ctx)
+{
+    return _PyAST_Name(e->v.Name.id, ctx, EXTRA_EXPR(e, e));
+}
+
+static expr_ty
+_set_tuple_context(Parser *p, expr_ty e, expr_context_ty ctx)
+{
+    return _PyAST_Tuple(
+            _set_seq_context(p, e->v.Tuple.elts, ctx),
+            ctx,
+            EXTRA_EXPR(e, e));
+}
+
+static expr_ty
+_set_list_context(Parser *p, expr_ty e, expr_context_ty ctx)
+{
+    return _PyAST_List(
+            _set_seq_context(p, e->v.List.elts, ctx),
+            ctx,
+            EXTRA_EXPR(e, e));
+}
+
+static expr_ty
+_set_subscript_context(Parser *p, expr_ty e, expr_context_ty ctx)
+{
+    return _PyAST_Subscript(e->v.Subscript.value, e->v.Subscript.slice,
+                            ctx, EXTRA_EXPR(e, e));
+}
+
+static expr_ty
+_set_attribute_context(Parser *p, expr_ty e, expr_context_ty ctx)
+{
+    return _PyAST_Attribute(e->v.Attribute.value, e->v.Attribute.attr,
+                            ctx, EXTRA_EXPR(e, e));
+}
+
+static expr_ty
+_set_starred_context(Parser *p, expr_ty e, expr_context_ty ctx)
+{
+    return _PyAST_Starred(_PyPegen_set_expr_context(p, e->v.Starred.value, ctx),
+                          ctx, EXTRA_EXPR(e, e));
+}
+
+/* Creates an `expr_ty` equivalent to `expr` but with `ctx` as context */
+expr_ty
+_PyPegen_set_expr_context(Parser *p, expr_ty expr, expr_context_ty ctx)
+{
+    assert(expr != NULL);
+
+    expr_ty new = NULL;
+    switch (expr->kind) {
+        case Name_kind:
+            new = _set_name_context(p, expr, ctx);
+            break;
+        case Tuple_kind:
+            new = _set_tuple_context(p, expr, ctx);
+            break;
+        case List_kind:
+            new = _set_list_context(p, expr, ctx);
+            break;
+        case Subscript_kind:
+            new = _set_subscript_context(p, expr, ctx);
+            break;
+        case Attribute_kind:
+            new = _set_attribute_context(p, expr, ctx);
+            break;
+        case Starred_kind:
+            new = _set_starred_context(p, expr, ctx);
+            break;
+        default:
+            new = expr;
+    }
+    return new;
+}
+
+/* Constructs a KeyValuePair that is used when parsing a dict's key value pairs */
+KeyValuePair *
+_PyPegen_key_value_pair(Parser *p, expr_ty key, expr_ty value)
+{
+    KeyValuePair *a = _PyArena_Malloc(p->arena, sizeof(KeyValuePair));
+    if (!a) {
+        return NULL;
+    }
+    a->key = key;
+    a->value = value;
+    return a;
+}
+
+/* Extracts all keys from an asdl_seq* of KeyValuePair*'s */
+asdl_expr_seq *
+_PyPegen_get_keys(Parser *p, asdl_seq *seq)
+{
+    Py_ssize_t len = asdl_seq_LEN(seq);
+    asdl_expr_seq *new_seq = _Py_asdl_expr_seq_new(len, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+    for (Py_ssize_t i = 0; i < len; i++) {
+        KeyValuePair *pair = asdl_seq_GET_UNTYPED(seq, i);
+        asdl_seq_SET(new_seq, i, pair->key);
+    }
+    return new_seq;
+}
+
+/* Extracts all values from an asdl_seq* of KeyValuePair*'s */
+asdl_expr_seq *
+_PyPegen_get_values(Parser *p, asdl_seq *seq)
+{
+    Py_ssize_t len = asdl_seq_LEN(seq);
+    asdl_expr_seq *new_seq = _Py_asdl_expr_seq_new(len, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+    for (Py_ssize_t i = 0; i < len; i++) {
+        KeyValuePair *pair = asdl_seq_GET_UNTYPED(seq, i);
+        asdl_seq_SET(new_seq, i, pair->value);
+    }
+    return new_seq;
+}
+
+/* Constructs a KeyPatternPair that is used when parsing mapping & class patterns */
+KeyPatternPair *
+_PyPegen_key_pattern_pair(Parser *p, expr_ty key, pattern_ty pattern)
+{
+    KeyPatternPair *a = _PyArena_Malloc(p->arena, sizeof(KeyPatternPair));
+    if (!a) {
+        return NULL;
+    }
+    a->key = key;
+    a->pattern = pattern;
+    return a;
+}
+
+/* Extracts all keys from an asdl_seq* of KeyPatternPair*'s */
+asdl_expr_seq *
+_PyPegen_get_pattern_keys(Parser *p, asdl_seq *seq)
+{
+    Py_ssize_t len = asdl_seq_LEN(seq);
+    asdl_expr_seq *new_seq = _Py_asdl_expr_seq_new(len, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+    for (Py_ssize_t i = 0; i < len; i++) {
+        KeyPatternPair *pair = asdl_seq_GET_UNTYPED(seq, i);
+        asdl_seq_SET(new_seq, i, pair->key);
+    }
+    return new_seq;
+}
+
+/* Extracts all patterns from an asdl_seq* of KeyPatternPair*'s */
+asdl_pattern_seq *
+_PyPegen_get_patterns(Parser *p, asdl_seq *seq)
+{
+    Py_ssize_t len = asdl_seq_LEN(seq);
+    asdl_pattern_seq *new_seq = _Py_asdl_pattern_seq_new(len, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+    for (Py_ssize_t i = 0; i < len; i++) {
+        KeyPatternPair *pair = asdl_seq_GET_UNTYPED(seq, i);
+        asdl_seq_SET(new_seq, i, pair->pattern);
+    }
+    return new_seq;
+}
+
+/* Constructs a NameDefaultPair */
+NameDefaultPair *
+_PyPegen_name_default_pair(Parser *p, arg_ty arg, expr_ty value, Token *tc)
+{
+    NameDefaultPair *a = _PyArena_Malloc(p->arena, sizeof(NameDefaultPair));
+    if (!a) {
+        return NULL;
+    }
+    a->arg = _PyPegen_add_type_comment_to_arg(p, arg, tc);
+    a->value = value;
+    return a;
+}
+
+/* Constructs a SlashWithDefault */
+SlashWithDefault *
+_PyPegen_slash_with_default(Parser *p, asdl_arg_seq *plain_names, asdl_seq *names_with_defaults)
+{
+    SlashWithDefault *a = _PyArena_Malloc(p->arena, sizeof(SlashWithDefault));
+    if (!a) {
+        return NULL;
+    }
+    a->plain_names = plain_names;
+    a->names_with_defaults = names_with_defaults;
+    return a;
+}
+
+/* Constructs a StarEtc */
+StarEtc *
+_PyPegen_star_etc(Parser *p, arg_ty vararg, asdl_seq *kwonlyargs, arg_ty kwarg)
+{
+    StarEtc *a = _PyArena_Malloc(p->arena, sizeof(StarEtc));
+    if (!a) {
+        return NULL;
+    }
+    a->vararg = vararg;
+    a->kwonlyargs = kwonlyargs;
+    a->kwarg = kwarg;
+    return a;
+}
+
+asdl_seq *
+_PyPegen_join_sequences(Parser *p, asdl_seq *a, asdl_seq *b)
+{
+    Py_ssize_t first_len = asdl_seq_LEN(a);
+    Py_ssize_t second_len = asdl_seq_LEN(b);
+    asdl_seq *new_seq = (asdl_seq*)_Py_asdl_generic_seq_new(first_len + second_len, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+
+    int k = 0;
+    for (Py_ssize_t i = 0; i < first_len; i++) {
+        asdl_seq_SET_UNTYPED(new_seq, k++, asdl_seq_GET_UNTYPED(a, i));
+    }
+    for (Py_ssize_t i = 0; i < second_len; i++) {
+        asdl_seq_SET_UNTYPED(new_seq, k++, asdl_seq_GET_UNTYPED(b, i));
+    }
+
+    return new_seq;
+}
+
+static asdl_arg_seq*
+_get_names(Parser *p, asdl_seq *names_with_defaults)
+{
+    Py_ssize_t len = asdl_seq_LEN(names_with_defaults);
+    asdl_arg_seq *seq = _Py_asdl_arg_seq_new(len, p->arena);
+    if (!seq) {
+        return NULL;
+    }
+    for (Py_ssize_t i = 0; i < len; i++) {
+        NameDefaultPair *pair = asdl_seq_GET_UNTYPED(names_with_defaults, i);
+        asdl_seq_SET(seq, i, pair->arg);
+    }
+    return seq;
+}
+
+static asdl_expr_seq *
+_get_defaults(Parser *p, asdl_seq *names_with_defaults)
+{
+    Py_ssize_t len = asdl_seq_LEN(names_with_defaults);
+    asdl_expr_seq *seq = _Py_asdl_expr_seq_new(len, p->arena);
+    if (!seq) {
+        return NULL;
+    }
+    for (Py_ssize_t i = 0; i < len; i++) {
+        NameDefaultPair *pair = asdl_seq_GET_UNTYPED(names_with_defaults, i);
+        asdl_seq_SET(seq, i, pair->value);
+    }
+    return seq;
+}
+
+static int
+_make_posonlyargs(Parser *p,
+                  asdl_arg_seq *slash_without_default,
+                  SlashWithDefault *slash_with_default,
+                  asdl_arg_seq **posonlyargs) {
+    if (slash_without_default != NULL) {
+        *posonlyargs = slash_without_default;
+    }
+    else if (slash_with_default != NULL) {
+        asdl_arg_seq *slash_with_default_names =
+                _get_names(p, slash_with_default->names_with_defaults);
+        if (!slash_with_default_names) {
+            return -1;
+        }
+        *posonlyargs = (asdl_arg_seq*)_PyPegen_join_sequences(
+                p,
+                (asdl_seq*)slash_with_default->plain_names,
+                (asdl_seq*)slash_with_default_names);
+    }
+    else {
+        *posonlyargs = _Py_asdl_arg_seq_new(0, p->arena);
+    }
+    return *posonlyargs == NULL ? -1 : 0;
+}
+
+static int
+_make_posargs(Parser *p,
+              asdl_arg_seq *plain_names,
+              asdl_seq *names_with_default,
+              asdl_arg_seq **posargs) {
+    if (plain_names != NULL && names_with_default != NULL) {
+        asdl_arg_seq *names_with_default_names = _get_names(p, names_with_default);
+        if (!names_with_default_names) {
+            return -1;
+        }
+        *posargs = (asdl_arg_seq*)_PyPegen_join_sequences(
+                p,(asdl_seq*)plain_names, (asdl_seq*)names_with_default_names);
+    }
+    else if (plain_names == NULL && names_with_default != NULL) {
+        *posargs = _get_names(p, names_with_default);
+    }
+    else if (plain_names != NULL && names_with_default == NULL) {
+        *posargs = plain_names;
+    }
+    else {
+        *posargs = _Py_asdl_arg_seq_new(0, p->arena);
+    }
+    return *posargs == NULL ? -1 : 0;
+}
+
+static int
+_make_posdefaults(Parser *p,
+                  SlashWithDefault *slash_with_default,
+                  asdl_seq *names_with_default,
+                  asdl_expr_seq **posdefaults) {
+    if (slash_with_default != NULL && names_with_default != NULL) {
+        asdl_expr_seq *slash_with_default_values =
+                _get_defaults(p, slash_with_default->names_with_defaults);
+        if (!slash_with_default_values) {
+            return -1;
+        }
+        asdl_expr_seq *names_with_default_values = _get_defaults(p, names_with_default);
+        if (!names_with_default_values) {
+            return -1;
+        }
+        *posdefaults = (asdl_expr_seq*)_PyPegen_join_sequences(
+                p,
+                (asdl_seq*)slash_with_default_values,
+                (asdl_seq*)names_with_default_values);
+    }
+    else if (slash_with_default == NULL && names_with_default != NULL) {
+        *posdefaults = _get_defaults(p, names_with_default);
+    }
+    else if (slash_with_default != NULL && names_with_default == NULL) {
+        *posdefaults = _get_defaults(p, slash_with_default->names_with_defaults);
+    }
+    else {
+        *posdefaults = _Py_asdl_expr_seq_new(0, p->arena);
+    }
+    return *posdefaults == NULL ? -1 : 0;
+}
+
+static int
+_make_kwargs(Parser *p, StarEtc *star_etc,
+             asdl_arg_seq **kwonlyargs,
+             asdl_expr_seq **kwdefaults) {
+    if (star_etc != NULL && star_etc->kwonlyargs != NULL) {
+        *kwonlyargs = _get_names(p, star_etc->kwonlyargs);
+    }
+    else {
+        *kwonlyargs = _Py_asdl_arg_seq_new(0, p->arena);
+    }
+
+    if (*kwonlyargs == NULL) {
+        return -1;
+    }
+
+    if (star_etc != NULL && star_etc->kwonlyargs != NULL) {
+        *kwdefaults = _get_defaults(p, star_etc->kwonlyargs);
+    }
+    else {
+        *kwdefaults = _Py_asdl_expr_seq_new(0, p->arena);
+    }
+
+    if (*kwdefaults == NULL) {
+        return -1;
+    }
+
+    return 0;
+}
+
+/* Constructs an arguments_ty object out of all the parsed constructs in the parameters rule */
+arguments_ty
+_PyPegen_make_arguments(Parser *p, asdl_arg_seq *slash_without_default,
+                        SlashWithDefault *slash_with_default, asdl_arg_seq *plain_names,
+                        asdl_seq *names_with_default, StarEtc *star_etc)
+{
+    asdl_arg_seq *posonlyargs;
+    if (_make_posonlyargs(p, slash_without_default, slash_with_default, &posonlyargs) == -1) {
+        return NULL;
+    }
+
+    asdl_arg_seq *posargs;
+    if (_make_posargs(p, plain_names, names_with_default, &posargs) == -1) {
+        return NULL;
+    }
+
+    asdl_expr_seq *posdefaults;
+    if (_make_posdefaults(p,slash_with_default, names_with_default, &posdefaults) == -1) {
+        return NULL;
+    }
+
+    arg_ty vararg = NULL;
+    if (star_etc != NULL && star_etc->vararg != NULL) {
+        vararg = star_etc->vararg;
+    }
+
+    asdl_arg_seq *kwonlyargs;
+    asdl_expr_seq *kwdefaults;
+    if (_make_kwargs(p, star_etc, &kwonlyargs, &kwdefaults) == -1) {
+        return NULL;
+    }
+
+    arg_ty kwarg = NULL;
+    if (star_etc != NULL && star_etc->kwarg != NULL) {
+        kwarg = star_etc->kwarg;
+    }
+
+    return _PyAST_arguments(posonlyargs, posargs, vararg, kwonlyargs,
+                            kwdefaults, kwarg, posdefaults, p->arena);
+}
+
+
+/* Constructs an empty arguments_ty object, that gets used when a function accepts no
+ * arguments. */
+arguments_ty
+_PyPegen_empty_arguments(Parser *p)
+{
+    asdl_arg_seq *posonlyargs = _Py_asdl_arg_seq_new(0, p->arena);
+    if (!posonlyargs) {
+        return NULL;
+    }
+    asdl_arg_seq *posargs = _Py_asdl_arg_seq_new(0, p->arena);
+    if (!posargs) {
+        return NULL;
+    }
+    asdl_expr_seq *posdefaults = _Py_asdl_expr_seq_new(0, p->arena);
+    if (!posdefaults) {
+        return NULL;
+    }
+    asdl_arg_seq *kwonlyargs = _Py_asdl_arg_seq_new(0, p->arena);
+    if (!kwonlyargs) {
+        return NULL;
+    }
+    asdl_expr_seq *kwdefaults = _Py_asdl_expr_seq_new(0, p->arena);
+    if (!kwdefaults) {
+        return NULL;
+    }
+
+    return _PyAST_arguments(posonlyargs, posargs, NULL, kwonlyargs,
+                            kwdefaults, NULL, posdefaults, p->arena);
+}
+
+/* Encapsulates the value of an operator_ty into an AugOperator struct */
+AugOperator *
+_PyPegen_augoperator(Parser *p, operator_ty kind)
+{
+    AugOperator *a = _PyArena_Malloc(p->arena, sizeof(AugOperator));
+    if (!a) {
+        return NULL;
+    }
+    a->kind = kind;
+    return a;
+}
+
+/* Construct a FunctionDef equivalent to function_def, but with decorators */
+stmt_ty
+_PyPegen_function_def_decorators(Parser *p, asdl_expr_seq *decorators, stmt_ty function_def)
+{
+    assert(function_def != NULL);
+    if (function_def->kind == AsyncFunctionDef_kind) {
+        return _PyAST_AsyncFunctionDef(
+            function_def->v.AsyncFunctionDef.name,
+            function_def->v.AsyncFunctionDef.args,
+            function_def->v.AsyncFunctionDef.body, decorators,
+            function_def->v.AsyncFunctionDef.returns,
+            function_def->v.AsyncFunctionDef.type_comment,
+            function_def->v.AsyncFunctionDef.type_params,
+            function_def->lineno, function_def->col_offset,
+            function_def->end_lineno, function_def->end_col_offset, p->arena);
+    }
+
+    return _PyAST_FunctionDef(
+        function_def->v.FunctionDef.name,
+        function_def->v.FunctionDef.args,
+        function_def->v.FunctionDef.body, decorators,
+        function_def->v.FunctionDef.returns,
+        function_def->v.FunctionDef.type_comment,
+        function_def->v.FunctionDef.type_params,
+        function_def->lineno, function_def->col_offset,
+        function_def->end_lineno, function_def->end_col_offset, p->arena);
+}
+
+/* Construct a ClassDef equivalent to class_def, but with decorators */
+stmt_ty
+_PyPegen_class_def_decorators(Parser *p, asdl_expr_seq *decorators, stmt_ty class_def)
+{
+    assert(class_def != NULL);
+    return _PyAST_ClassDef(
+        class_def->v.ClassDef.name,
+        class_def->v.ClassDef.bases, class_def->v.ClassDef.keywords,
+        class_def->v.ClassDef.body, decorators,
+        class_def->v.ClassDef.type_params,
+        class_def->lineno, class_def->col_offset, class_def->end_lineno,
+        class_def->end_col_offset, p->arena);
+}
+
+/* Construct a KeywordOrStarred */
+KeywordOrStarred *
+_PyPegen_keyword_or_starred(Parser *p, void *element, int is_keyword)
+{
+    KeywordOrStarred *a = _PyArena_Malloc(p->arena, sizeof(KeywordOrStarred));
+    if (!a) {
+        return NULL;
+    }
+    a->element = element;
+    a->is_keyword = is_keyword;
+    return a;
+}
+
+/* Get the number of starred expressions in an asdl_seq* of KeywordOrStarred*s */
+static int
+_seq_number_of_starred_exprs(asdl_seq *seq)
+{
+    int n = 0;
+    for (Py_ssize_t i = 0, l = asdl_seq_LEN(seq); i < l; i++) {
+        KeywordOrStarred *k = asdl_seq_GET_UNTYPED(seq, i);
+        if (!k->is_keyword) {
+            n++;
+        }
+    }
+    return n;
+}
+
+/* Extract the starred expressions of an asdl_seq* of KeywordOrStarred*s */
+asdl_expr_seq *
+_PyPegen_seq_extract_starred_exprs(Parser *p, asdl_seq *kwargs)
+{
+    int new_len = _seq_number_of_starred_exprs(kwargs);
+    if (new_len == 0) {
+        return NULL;
+    }
+    asdl_expr_seq *new_seq = _Py_asdl_expr_seq_new(new_len, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+
+    int idx = 0;
+    for (Py_ssize_t i = 0, len = asdl_seq_LEN(kwargs); i < len; i++) {
+        KeywordOrStarred *k = asdl_seq_GET_UNTYPED(kwargs, i);
+        if (!k->is_keyword) {
+            asdl_seq_SET(new_seq, idx++, k->element);
+        }
+    }
+    return new_seq;
+}
+
+/* Return a new asdl_seq* with only the keywords in kwargs */
+asdl_keyword_seq*
+_PyPegen_seq_delete_starred_exprs(Parser *p, asdl_seq *kwargs)
+{
+    Py_ssize_t len = asdl_seq_LEN(kwargs);
+    Py_ssize_t new_len = len - _seq_number_of_starred_exprs(kwargs);
+    if (new_len == 0) {
+        return NULL;
+    }
+    asdl_keyword_seq *new_seq = _Py_asdl_keyword_seq_new(new_len, p->arena);
+    if (!new_seq) {
+        return NULL;
+    }
+
+    int idx = 0;
+    for (Py_ssize_t i = 0; i < len; i++) {
+        KeywordOrStarred *k = asdl_seq_GET_UNTYPED(kwargs, i);
+        if (k->is_keyword) {
+            asdl_seq_SET(new_seq, idx++, k->element);
+        }
+    }
+    return new_seq;
+}
+
+expr_ty
+_PyPegen_ensure_imaginary(Parser *p, expr_ty exp)
+{
+    if (exp->kind != Constant_kind || !PyComplex_CheckExact(exp->v.Constant.value)) {
+        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(exp, "imaginary number required in complex literal");
+        return NULL;
+    }
+    return exp;
+}
+
+expr_ty
+_PyPegen_ensure_real(Parser *p, expr_ty exp)
+{
+    if (exp->kind != Constant_kind || PyComplex_CheckExact(exp->v.Constant.value)) {
+        RAISE_SYNTAX_ERROR_KNOWN_LOCATION(exp, "real number required in complex literal");
+        return NULL;
+    }
+    return exp;
+}
+
+mod_ty
+_PyPegen_make_module(Parser *p, asdl_stmt_seq *a) {
+    asdl_type_ignore_seq *type_ignores = NULL;
+    Py_ssize_t num = p->type_ignore_comments.num_items;
+    if (num > 0) {
+        // Turn the raw (comment, lineno) pairs into TypeIgnore objects in the arena
+        type_ignores = _Py_asdl_type_ignore_seq_new(num, p->arena);
+        if (type_ignores == NULL) {
+            return NULL;
+        }
+        for (int i = 0; i < num; i++) {
+            PyObject *tag = _PyPegen_new_type_comment(p, p->type_ignore_comments.items[i].comment);
+            if (tag == NULL) {
+                return NULL;
+            }
+            type_ignore_ty ti = _PyAST_TypeIgnore(p->type_ignore_comments.items[i].lineno,
+                                                  tag, p->arena);
+            if (ti == NULL) {
+                return NULL;
+            }
+            asdl_seq_SET(type_ignores, i, ti);
+        }
+    }
+    return _PyAST_Module(a, type_ignores, p->arena);
+}
+
+PyObject *
+_PyPegen_new_type_comment(Parser *p, const char *s)
+{
+    PyObject *res = PyUnicode_DecodeUTF8(s, strlen(s), NULL);
+    if (res == NULL) {
+        return NULL;
+    }
+    if (_PyArena_AddPyObject(p->arena, res) < 0) {
+        Py_DECREF(res);
+        return NULL;
+    }
+    return res;
+}
+
+arg_ty
+_PyPegen_add_type_comment_to_arg(Parser *p, arg_ty a, Token *tc)
+{
+    if (tc == NULL) {
+        return a;
+    }
+    const char *bytes = PyBytes_AsString(tc->bytes);
+    if (bytes == NULL) {
+        return NULL;
+    }
+    PyObject *tco = _PyPegen_new_type_comment(p, bytes);
+    if (tco == NULL) {
+        return NULL;
+    }
+    return _PyAST_arg(a->arg, a->annotation, tco,
+                      a->lineno, a->col_offset, a->end_lineno, a->end_col_offset,
+                      p->arena);
+}
+
+/* Checks if the NOTEQUAL token is valid given the current parser flags
+0 indicates success and nonzero indicates failure (an exception may be set) */
+int
+_PyPegen_check_barry_as_flufl(Parser *p, Token* t) {
+    assert(t->bytes != NULL);
+    assert(t->type == NOTEQUAL);
+
+    const char* tok_str = PyBytes_AS_STRING(t->bytes);
+    if (p->flags & PyPARSE_BARRY_AS_BDFL && strcmp(tok_str, "<>") != 0) {
+        RAISE_SYNTAX_ERROR("with Barry as BDFL, use '<>' instead of '!='");
+        return -1;
+    }
+    if (!(p->flags & PyPARSE_BARRY_AS_BDFL)) {
+        return strcmp(tok_str, "!=");
+    }
+    return 0;
+}
+
+int
+_PyPegen_check_legacy_stmt(Parser *p, expr_ty name) {
+    if (name->kind != Name_kind) {
+        return 0;
+    }
+    const char* candidates[2] = {"print", "exec"};
+    for (int i=0; i<2; i++) {
+        if (PyUnicode_CompareWithASCIIString(name->v.Name.id, candidates[i]) == 0) {
+            return 1;
+        }
+    }
+    return 0;
+}
+
+static ResultTokenWithMetadata *
+result_token_with_metadata(Parser *p, void *result, PyObject *metadata)
+{
+    ResultTokenWithMetadata *res = _PyArena_Malloc(p->arena, sizeof(ResultTokenWithMetadata));
+    if (res == NULL) {
+        return NULL;
+    }
+    res->metadata = metadata;
+    res->result = result;
+    return res;
+}
+
+ResultTokenWithMetadata *
+_PyPegen_check_fstring_conversion(Parser *p, Token* conv_token, expr_ty conv)
+{
+    if (conv_token->lineno != conv->lineno || conv_token->end_col_offset != conv->col_offset) {
+        return RAISE_SYNTAX_ERROR_KNOWN_RANGE(
+            conv_token, conv,
+            "f-string: conversion type must come right after the exclamanation mark"
+        );
+    }
+    return result_token_with_metadata(p, conv, conv_token->metadata);
+}
+
+ResultTokenWithMetadata *
+_PyPegen_setup_full_format_spec(Parser *p, Token *colon, asdl_expr_seq *spec, int lineno, int col_offset,
+                                int end_lineno, int end_col_offset, PyArena *arena)
+{
+    if (!spec) {
+        return NULL;
+    }
+
+    // This is needed to keep compatibility with 3.11, where an empty format spec is parsed
+    // as an *empty* JoinedStr node, instead of having an empty constant in it.
+    if (asdl_seq_LEN(spec) == 1) {
+        expr_ty e = asdl_seq_GET(spec, 0);
+        if (e->kind == Constant_kind
+                && PyUnicode_Check(e->v.Constant.value)
+                && PyUnicode_GetLength(e->v.Constant.value) == 0) {
+            spec = _Py_asdl_expr_seq_new(0, arena);
+        }
+    }
+
+    expr_ty res = _PyAST_JoinedStr(spec, lineno, col_offset, end_lineno, end_col_offset, p->arena);
+    if (!res) {
+        return NULL;
+    }
+    return result_token_with_metadata(p, res, colon->metadata);
+}
+
+const char *
+_PyPegen_get_expr_name(expr_ty e)
+{
+    assert(e != NULL);
+    switch (e->kind) {
+        case Attribute_kind:
+            return "attribute";
+        case Subscript_kind:
+            return "subscript";
+        case Starred_kind:
+            return "starred";
+        case Name_kind:
+            return "name";
+        case List_kind:
+            return "list";
+        case Tuple_kind:
+            return "tuple";
+        case Lambda_kind:
+            return "lambda";
+        case Call_kind:
+            return "function call";
+        case BoolOp_kind:
+        case BinOp_kind:
+        case UnaryOp_kind:
+            return "expression";
+        case GeneratorExp_kind:
+            return "generator expression";
+        case Yield_kind:
+        case YieldFrom_kind:
+            return "yield expression";
+        case Await_kind:
+            return "await expression";
+        case ListComp_kind:
+            return "list comprehension";
+        case SetComp_kind:
+            return "set comprehension";
+        case DictComp_kind:
+            return "dict comprehension";
+        case Dict_kind:
+            return "dict literal";
+        case Set_kind:
+            return "set display";
+        case JoinedStr_kind:
+        case FormattedValue_kind:
+            return "f-string expression";
+        case Constant_kind: {
+            PyObject *value = e->v.Constant.value;
+            if (value == Py_None) {
+                return "None";
+            }
+            if (value == Py_False) {
+                return "False";
+            }
+            if (value == Py_True) {
+                return "True";
+            }
+            if (value == Py_Ellipsis) {
+                return "ellipsis";
+            }
+            return "literal";
+        }
+        case Compare_kind:
+            return "comparison";
+        case IfExp_kind:
+            return "conditional expression";
+        case NamedExpr_kind:
+            return "named expression";
+        default:
+            PyErr_Format(PyExc_SystemError,
+                         "unexpected expression in assignment %d (line %d)",
+                         e->kind, e->lineno);
+            return NULL;
+    }
+}
+
+expr_ty
+_PyPegen_get_last_comprehension_item(comprehension_ty comprehension) {
+    if (comprehension->ifs == NULL || asdl_seq_LEN(comprehension->ifs) == 0) {
+        return comprehension->iter;
+    }
+    return PyPegen_last_item(comprehension->ifs, expr_ty);
+}
+
+expr_ty _PyPegen_collect_call_seqs(Parser *p, asdl_expr_seq *a, asdl_seq *b,
+                     int lineno, int col_offset, int end_lineno,
+                     int end_col_offset, PyArena *arena) {
+    Py_ssize_t args_len = asdl_seq_LEN(a);
+    Py_ssize_t total_len = args_len;
+
+    if (b == NULL) {
+        return _PyAST_Call(_PyPegen_dummy_name(p), a, NULL, lineno, col_offset,
+                        end_lineno, end_col_offset, arena);
+
+    }
+
+    asdl_expr_seq *starreds = _PyPegen_seq_extract_starred_exprs(p, b);
+    asdl_keyword_seq *keywords = _PyPegen_seq_delete_starred_exprs(p, b);
+
+    if (starreds) {
+        total_len += asdl_seq_LEN(starreds);
+    }
+
+    asdl_expr_seq *args = _Py_asdl_expr_seq_new(total_len, arena);
+
+    Py_ssize_t i = 0;
+    for (i = 0; i < args_len; i++) {
+        asdl_seq_SET(args, i, asdl_seq_GET(a, i));
+    }
+    for (; i < total_len; i++) {
+        asdl_seq_SET(args, i, asdl_seq_GET(starreds, i - args_len));
+    }
+
+    return _PyAST_Call(_PyPegen_dummy_name(p), args, keywords, lineno,
+                       col_offset, end_lineno, end_col_offset, arena);
+}
+
+// AST Error reporting helpers
+
+expr_ty
+_PyPegen_get_invalid_target(expr_ty e, TARGETS_TYPE targets_type)
+{
+    if (e == NULL) {
+        return NULL;
+    }
+
+#define VISIT_CONTAINER(CONTAINER, TYPE) do { \
+        Py_ssize_t len = asdl_seq_LEN((CONTAINER)->v.TYPE.elts);\
+        for (Py_ssize_t i = 0; i < len; i++) {\
+            expr_ty other = asdl_seq_GET((CONTAINER)->v.TYPE.elts, i);\
+            expr_ty child = _PyPegen_get_invalid_target(other, targets_type);\
+            if (child != NULL) {\
+                return child;\
+            }\
+        }\
+    } while (0)
+
+    // We only need to visit List and Tuple nodes recursively as those
+    // are the only ones that can contain valid names in targets when
+    // they are parsed as expressions. Any other kind of expression
+    // that is a container (like Sets or Dicts) is directly invalid and
+    // we don't need to visit it recursively.
+
+    switch (e->kind) {
+        case List_kind:
+            VISIT_CONTAINER(e, List);
+            return NULL;
+        case Tuple_kind:
+            VISIT_CONTAINER(e, Tuple);
+            return NULL;
+        case Starred_kind:
+            if (targets_type == DEL_TARGETS) {
+                return e;
+            }
+            return _PyPegen_get_invalid_target(e->v.Starred.value, targets_type);
+        case Compare_kind:
+            // This is needed, because the `a in b` in `for a in b` gets parsed
+            // as a comparison, and so we need to search the left side of the comparison
+            // for invalid targets.
+            if (targets_type == FOR_TARGETS) {
+                cmpop_ty cmpop = (cmpop_ty) asdl_seq_GET(e->v.Compare.ops, 0);
+                if (cmpop == In) {
+                    return _PyPegen_get_invalid_target(e->v.Compare.left, targets_type);
+                }
+                return NULL;
+            }
+            return e;
+        case Name_kind:
+        case Subscript_kind:
+        case Attribute_kind:
+            return NULL;
+        default:
+            return e;
+    }
+}
+
+void *_PyPegen_arguments_parsing_error(Parser *p, expr_ty e) {
+    int kwarg_unpacking = 0;
+    for (Py_ssize_t i = 0, l = asdl_seq_LEN(e->v.Call.keywords); i < l; i++) {
+        keyword_ty keyword = asdl_seq_GET(e->v.Call.keywords, i);
+        if (!keyword->arg) {
+            kwarg_unpacking = 1;
+        }
+    }
+
+    const char *msg = NULL;
+    if (kwarg_unpacking) {
+        msg = "positional argument follows keyword argument unpacking";
+    } else {
+        msg = "positional argument follows keyword argument";
+    }
+
+    return RAISE_SYNTAX_ERROR(msg);
+}
+
+void *
+_PyPegen_nonparen_genexp_in_call(Parser *p, expr_ty args, asdl_comprehension_seq *comprehensions)
+{
+    /* The rule that calls this function is 'args for_if_clauses'.
+       For the input f(L, x for x in y), L and x are in args and
+       the for is parsed as a for_if_clause. We have to check if
+       len <= 1, so that input like dict((a, b) for a, b in x)
+       gets successfully parsed and then we pass the last
+       argument (x in the above example) as the location of the
+       error */
+    Py_ssize_t len = asdl_seq_LEN(args->v.Call.args);
+    if (len <= 1) {
+        return NULL;
+    }
+
+    comprehension_ty last_comprehension = PyPegen_last_item(comprehensions, comprehension_ty);
+
+    return RAISE_SYNTAX_ERROR_KNOWN_RANGE(
+        (expr_ty) asdl_seq_GET(args->v.Call.args, len - 1),
+        _PyPegen_get_last_comprehension_item(last_comprehension),
+        "Generator expression must be parenthesized"
+    );
+}
+
+// Fstring stuff
+
+static expr_ty
+_PyPegen_decode_fstring_part(Parser* p, int is_raw, expr_ty constant, Token* token) {
+    assert(PyUnicode_CheckExact(constant->v.Constant.value));
+
+    const char* bstr = PyUnicode_AsUTF8(constant->v.Constant.value);
+    if (bstr == NULL) {
+        return NULL;
+    }
+
+    size_t len;
+    if (strcmp(bstr, "{{") == 0 || strcmp(bstr, "}}") == 0) {
+        len = 1;
+    } else {
+        len = strlen(bstr);
+    }
+
+    is_raw = is_raw || strchr(bstr, '\\') == NULL;
+    PyObject *str = _PyPegen_decode_string(p, is_raw, bstr, len, token);
+    if (str == NULL) {
+        _Pypegen_raise_decode_error(p);
+        return NULL;
+    }
+    if (_PyArena_AddPyObject(p->arena, str) < 0) {
+        Py_DECREF(str);
+        return NULL;
+    }
+    return _PyAST_Constant(str, NULL, constant->lineno, constant->col_offset,
+                           constant->end_lineno, constant->end_col_offset,
+                           p->arena);
+}
+
+static asdl_expr_seq *
+unpack_top_level_joined_strs(Parser *p, asdl_expr_seq *raw_expressions)
+{
+    /* The parser might put multiple f-string values into an individual
+     * JoinedStr node at the top level due to stuff like f-string debugging
+     * expressions. This function flattens those and promotes them to the
+     * upper level. Only simplifies AST, but the compiler already takes care
+     * of the regular output, so this is not necessary if you are not going
+     * to expose the output AST to Python level. */
+
+    Py_ssize_t i, req_size, raw_size;
+
+    req_size = raw_size = asdl_seq_LEN(raw_expressions);
+    expr_ty expr;
+    for (i = 0; i < raw_size; i++) {
+        expr = asdl_seq_GET(raw_expressions, i);
+        if (expr->kind == JoinedStr_kind) {
+            req_size += asdl_seq_LEN(expr->v.JoinedStr.values) - 1;
+        }
+    }
+
+    asdl_expr_seq *expressions = _Py_asdl_expr_seq_new(req_size, p->arena);
+
+    Py_ssize_t raw_index, req_index = 0;
+    for (raw_index = 0; raw_index < raw_size; raw_index++) {
+        expr = asdl_seq_GET(raw_expressions, raw_index);
+        if (expr->kind == JoinedStr_kind) {
+            asdl_expr_seq *values = expr->v.JoinedStr.values;
+            for (Py_ssize_t n = 0; n < asdl_seq_LEN(values); n++) {
+                asdl_seq_SET(expressions, req_index, asdl_seq_GET(values, n));
+                req_index++;
+            }
+        } else {
+            asdl_seq_SET(expressions, req_index, expr);
+            req_index++;
+        }
+    }
+    return expressions;
+}
+
+expr_ty
+_PyPegen_joined_str(Parser *p, Token* a, asdl_expr_seq* raw_expressions, Token*b) {
+    asdl_expr_seq *expr = unpack_top_level_joined_strs(p, raw_expressions);
+    Py_ssize_t n_items = asdl_seq_LEN(expr);
+
+    const char* quote_str = PyBytes_AsString(a->bytes);
+    if (quote_str == NULL) {
+        return NULL;
+    }
+    int is_raw = strpbrk(quote_str, "rR") != NULL;
+
+    asdl_expr_seq *seq = _Py_asdl_expr_seq_new(n_items, p->arena);
+    if (seq == NULL) {
+        return NULL;
+    }
+
+    Py_ssize_t index = 0;
+    for (Py_ssize_t i = 0; i < n_items; i++) {
+        expr_ty item = asdl_seq_GET(expr, i);
+        if (item->kind == Constant_kind) {
+            item = _PyPegen_decode_fstring_part(p, is_raw, item, b);
+            if (item == NULL) {
+                return NULL;
+            }
+
+            /* Tokenizer emits string parts even when the underlying string
+            might become an empty value (e.g. FSTRING_MIDDLE with the value \\n)
+            so we need to check for them and simplify it here. */
+            if (PyUnicode_CheckExact(item->v.Constant.value)
+                && PyUnicode_GET_LENGTH(item->v.Constant.value) == 0) {
+                continue;
+            }
+        }
+        asdl_seq_SET(seq, index++, item);
+    }
+
+    asdl_expr_seq *resized_exprs;
+    if (index != n_items) {
+        resized_exprs = _Py_asdl_expr_seq_new(index, p->arena);
+        if (resized_exprs == NULL) {
+            return NULL;
+        }
+        for (Py_ssize_t i = 0; i < index; i++) {
+            asdl_seq_SET(resized_exprs, i, asdl_seq_GET(seq, i));
+        }
+    }
+    else {
+        resized_exprs = seq;
+    }
+
+    return _PyAST_JoinedStr(resized_exprs, a->lineno, a->col_offset,
+                            b->end_lineno, b->end_col_offset,
+                            p->arena);
+}
+
+expr_ty _PyPegen_decoded_constant_from_token(Parser* p, Token* tok) {
+    Py_ssize_t bsize;
+    char* bstr;
+    if (PyBytes_AsStringAndSize(tok->bytes, &bstr, &bsize) == -1) {
+        return NULL;
+    }
+    PyObject* str = _PyPegen_decode_string(p, 0, bstr, bsize, tok);
+    if (str == NULL) {
+        return NULL;
+    }
+    if (_PyArena_AddPyObject(p->arena, str) < 0) {
+        Py_DECREF(str);
+        return NULL;
+    }
+    return _PyAST_Constant(str, NULL, tok->lineno, tok->col_offset,
+                           tok->end_lineno, tok->end_col_offset,
+                           p->arena);
+}
+
+expr_ty _PyPegen_constant_from_token(Parser* p, Token* tok) {
+    char* bstr = PyBytes_AsString(tok->bytes);
+    if (bstr == NULL) {
+        return NULL;
+    }
+    PyObject* str = PyUnicode_FromString(bstr);
+    if (str == NULL) {
+        return NULL;
+    }
+    if (_PyArena_AddPyObject(p->arena, str) < 0) {
+        Py_DECREF(str);
+        return NULL;
+    }
+    return _PyAST_Constant(str, NULL, tok->lineno, tok->col_offset,
+                           tok->end_lineno, tok->end_col_offset,
+                           p->arena);
+}
+
+expr_ty _PyPegen_constant_from_string(Parser* p, Token* tok) {
+    char* the_str = PyBytes_AsString(tok->bytes);
+    if (the_str == NULL) {
+        return NULL;
+    }
+    PyObject *s = _PyPegen_parse_string(p, tok);
+    if (s == NULL) {
+        _Pypegen_raise_decode_error(p);
+        return NULL;
+    }
+    if (_PyArena_AddPyObject(p->arena, s) < 0) {
+        Py_DECREF(s);
+        return NULL;
+    }
+    PyObject *kind = NULL;
+    if (the_str && the_str[0] == 'u') {
+        kind = _PyPegen_new_identifier(p, "u");
+        if (kind == NULL) {
+            return NULL;
+        }
+    }
+    return _PyAST_Constant(s, kind, tok->lineno, tok->col_offset, tok->end_lineno, tok->end_col_offset, p->arena);
+}
+
+expr_ty _PyPegen_formatted_value(Parser *p, expr_ty expression, Token *debug, ResultTokenWithMetadata *conversion,
+                                 ResultTokenWithMetadata *format, Token *closing_brace, int lineno, int col_offset,
+                                 int end_lineno, int end_col_offset, PyArena *arena) {
+    int conversion_val = -1;
+    if (conversion != NULL) {
+        expr_ty conversion_expr = (expr_ty) conversion->result;
+        assert(conversion_expr->kind == Name_kind);
+        Py_UCS4 first = PyUnicode_READ_CHAR(conversion_expr->v.Name.id, 0);
+
+        if (PyUnicode_GET_LENGTH(conversion_expr->v.Name.id) > 1 ||
+            !(first == 's' || first == 'r' || first == 'a')) {
+            RAISE_SYNTAX_ERROR_KNOWN_LOCATION(conversion_expr,
+                                              "f-string: invalid conversion character %R: expected 's', 'r', or 'a'",
+                                              conversion_expr->v.Name.id);
+            return NULL;
+        }
+
+        conversion_val = Py_SAFE_DOWNCAST(first, Py_UCS4, int);
+    }
+    else if (debug && !format) {
+        /* If no conversion is specified, use !r for debug expressions */
+        conversion_val = (int)'r';
+    }
+
+    expr_ty formatted_value = _PyAST_FormattedValue(
+        expression, conversion_val, format ? (expr_ty) format->result : NULL,
+        lineno, col_offset, end_lineno,
+        end_col_offset, arena
+    );
+
+    if (debug) {
+        /* Find the non whitespace token after the "=" */
+        int debug_end_line, debug_end_offset;
+        PyObject *debug_metadata;
+
+        if (conversion) {
+            debug_end_line = ((expr_ty) conversion->result)->lineno;
+            debug_end_offset = ((expr_ty) conversion->result)->col_offset;
+            debug_metadata = conversion->metadata;
+        }
+        else if (format) {
+            debug_end_line = ((expr_ty) format->result)->lineno;
+            debug_end_offset = ((expr_ty) format->result)->col_offset + 1;
+            debug_metadata = format->metadata;
+        }
+        else {
+            debug_end_line = end_lineno;
+            debug_end_offset = end_col_offset;
+            debug_metadata = closing_brace->metadata;
+        }
+
+        expr_ty debug_text = _PyAST_Constant(debug_metadata, NULL, lineno, col_offset + 1, debug_end_line,
+                                             debug_end_offset - 1, p->arena);
+        if (!debug_text) {
+            return NULL;
+        }
+
+        asdl_expr_seq *values = _Py_asdl_expr_seq_new(2, arena);
+        asdl_seq_SET(values, 0, debug_text);
+        asdl_seq_SET(values, 1, formatted_value);
+        return _PyAST_JoinedStr(values, lineno, col_offset, debug_end_line, debug_end_offset, p->arena);
+    }
+    else {
+        return formatted_value;
+    }
+}
+
+expr_ty
+_PyPegen_concatenate_strings(Parser *p, asdl_expr_seq *strings,
+                             int lineno, int col_offset, int end_lineno,
+                             int end_col_offset, PyArena *arena)
+{
+    Py_ssize_t len = asdl_seq_LEN(strings);
+    assert(len > 0);
+
+    int f_string_found = 0;
+    int unicode_string_found = 0;
+    int bytes_found = 0;
+
+    Py_ssize_t i = 0;
+    Py_ssize_t n_flattened_elements = 0;
+    for (i = 0; i < len; i++) {
+        expr_ty elem = asdl_seq_GET(strings, i);
+        if (elem->kind == Constant_kind) {
+            if (PyBytes_CheckExact(elem->v.Constant.value)) {
+                bytes_found = 1;
+            } else {
+                unicode_string_found = 1;
+            }
+            n_flattened_elements++;
+        } else {
+            n_flattened_elements += asdl_seq_LEN(elem->v.JoinedStr.values);
+            f_string_found = 1;
+        }
+    }
+
+    if ((unicode_string_found || f_string_found) && bytes_found) {
+        RAISE_SYNTAX_ERROR("cannot mix bytes and nonbytes literals");
+        return NULL;
+    }
+
+    if (bytes_found) {
+        PyObject* res = PyBytes_FromString("");
+
+        /* Bytes literals never get a kind, but just for consistency
+           since they are represented as Constant nodes, we'll mirror
+           the same behavior as unicode strings for determining the
+           kind. */
+        PyObject* kind = asdl_seq_GET(strings, 0)->v.Constant.kind;
+        for (i = 0; i < len; i++) {
+            expr_ty elem = asdl_seq_GET(strings, i);
+            PyBytes_Concat(&res, elem->v.Constant.value);
+        }
+        if (!res || _PyArena_AddPyObject(arena, res) < 0) {
+            Py_XDECREF(res);
+            return NULL;
+        }
+        return _PyAST_Constant(res, kind, lineno, col_offset, end_lineno, end_col_offset, p->arena);
+    }
+
+    if (!f_string_found && len == 1) {
+        return asdl_seq_GET(strings, 0);
+    }
+
+    asdl_expr_seq* flattened = _Py_asdl_expr_seq_new(n_flattened_elements, p->arena);
+    if (flattened == NULL) {
+        return NULL;
+    }
+
+    /* build flattened list */
+    Py_ssize_t current_pos = 0;
+    Py_ssize_t j = 0;
+    for (i = 0; i < len; i++) {
+        expr_ty elem = asdl_seq_GET(strings, i);
+        if (elem->kind == Constant_kind) {
+            asdl_seq_SET(flattened, current_pos++, elem);
+        } else {
+            for (j = 0; j < asdl_seq_LEN(elem->v.JoinedStr.values); j++) {
+                expr_ty subvalue = asdl_seq_GET(elem->v.JoinedStr.values, j);
+                if (subvalue == NULL) {
+                    return NULL;
+                }
+                asdl_seq_SET(flattened, current_pos++, subvalue);
+            }
+        }
+    }
+
+    /* calculate folded element count */
+    Py_ssize_t n_elements = 0;
+    int prev_is_constant = 0;
+    for (i = 0; i < n_flattened_elements; i++) {
+        expr_ty elem = asdl_seq_GET(flattened, i);
+
+        /* The concatenation of a FormattedValue and an empty Contant should
+           lead to the FormattedValue itself. Thus, we will not take any empty
+           constants into account, just as in `_PyPegen_joined_str` */
+        if (f_string_found && elem->kind == Constant_kind &&
+            PyUnicode_CheckExact(elem->v.Constant.value) &&
+            PyUnicode_GET_LENGTH(elem->v.Constant.value) == 0)
+            continue;
+
+        if (!prev_is_constant || elem->kind != Constant_kind) {
+            n_elements++;
+        }
+        prev_is_constant = elem->kind == Constant_kind;
+    }
+
+    asdl_expr_seq* values = _Py_asdl_expr_seq_new(n_elements, p->arena);
+    if (values == NULL) {
+        return NULL;
+    }
+
+    /* build folded list */
+    _PyUnicodeWriter writer;
+    current_pos = 0;
+    for (i = 0; i < n_flattened_elements; i++) {
+        expr_ty elem = asdl_seq_GET(flattened, i);
+
+        /* if the current elem and the following are constants,
+           fold them and all consequent constants */
+        if (elem->kind == Constant_kind) {
+            if (i + 1 < n_flattened_elements &&
+                asdl_seq_GET(flattened, i + 1)->kind == Constant_kind) {
+                expr_ty first_elem = elem;
+
+                /* When a string is getting concatenated, the kind of the string
+                   is determined by the first string in the concatenation
+                   sequence.
+
+                   u"abc" "def" -> u"abcdef"
+                   "abc" u"abc" ->  "abcabc" */
+                PyObject *kind = elem->v.Constant.kind;
+
+                _PyUnicodeWriter_Init(&writer);
+                expr_ty last_elem = elem;
+                for (j = i; j < n_flattened_elements; j++) {
+                    expr_ty current_elem = asdl_seq_GET(flattened, j);
+                    if (current_elem->kind == Constant_kind) {
+                        if (_PyUnicodeWriter_WriteStr(
+                                &writer, current_elem->v.Constant.value)) {
+                            _PyUnicodeWriter_Dealloc(&writer);
+                            return NULL;
+                        }
+                        last_elem = current_elem;
+                    } else {
+                        break;
+                    }
+                }
+                i = j - 1;
+
+                PyObject *concat_str = _PyUnicodeWriter_Finish(&writer);
+                if (concat_str == NULL) {
+                    _PyUnicodeWriter_Dealloc(&writer);
+                    return NULL;
+                }
+                if (_PyArena_AddPyObject(p->arena, concat_str) < 0) {
+                    Py_DECREF(concat_str);
+                    return NULL;
+                }
+                elem = _PyAST_Constant(concat_str, kind, first_elem->lineno,
+                                       first_elem->col_offset,
+                                       last_elem->end_lineno,
+                                       last_elem->end_col_offset, p->arena);
+                if (elem == NULL) {
+                    return NULL;
+                }
+            }
+
+            /* Drop all empty contanst strings */
+            if (f_string_found &&
+                PyUnicode_CheckExact(elem->v.Constant.value) &&
+                PyUnicode_GET_LENGTH(elem->v.Constant.value) == 0) {
+                continue;
+            }
+        }
+
+        asdl_seq_SET(values, current_pos++, elem);
+    }
+
+    if (!f_string_found) {
+        assert(n_elements == 1);
+        expr_ty elem = asdl_seq_GET(values, 0);
+        assert(elem->kind == Constant_kind);
+        return elem;
+    }
+
+    assert(current_pos == n_elements);
+    return _PyAST_JoinedStr(values, lineno, col_offset, end_lineno, end_col_offset, p->arena);
+}