lavu: add escape API

The escape API will be useful to perform escaping programmatically, which
is required when crafting argument strings, and will be used for context
printing as well.

This is based on the ffescape tool code, with a few extensions and fixes.

1 files changed, 20 insertions, 73 deletions

diff --git a/tools/ffescape.c b/tools/ffescape.c
index d777fe4572..0530d28c6d 100644
--- a/tools/ffescape.c
+++ b/tools/ffescape.c
@@ -42,80 +42,16 @@ static void usage(void)
     printf("\n"
            "Options:\n"
            "-e                echo each input line on output\n"
+           "-f flag           select an escape flag, can assume the values 'whitespace' and 'strict'\n"
            "-h                print this help\n"
            "-i INFILE         set INFILE as input file, stdin if omitted\n"
            "-l LEVEL          set the number of escaping levels, 1 if omitted\n"
-           "-m ESCAPE_MODE    select escape mode between 'full', 'lazy', 'quote', default is 'lazy'\n"
+           "-m ESCAPE_MODE    select escape mode between 'auto', 'backslash', 'quote'\n"
            "-o OUTFILE        set OUTFILE as output file, stdout if omitted\n"
            "-p PROMPT         set output prompt, is '=> ' by default\n"
            "-s SPECIAL_CHARS  set the list of special characters\n");
 }
 
-#define WHITESPACES " \n\t"
-
-enum EscapeMode {
-    ESCAPE_MODE_FULL,
-    ESCAPE_MODE_LAZY,
-    ESCAPE_MODE_QUOTE,
-};
-
-static int escape(char **dst, const char *src, const char *special_chars,
-                  enum EscapeMode mode)
-{
-    AVBPrint dstbuf;
-
-    av_bprint_init(&dstbuf, 1, AV_BPRINT_SIZE_UNLIMITED);
-
-    switch (mode) {
-    case ESCAPE_MODE_FULL:
-    case ESCAPE_MODE_LAZY:
-        /* \-escape characters */
-
-        if (mode == ESCAPE_MODE_LAZY && strchr(WHITESPACES, *src))
-            av_bprintf(&dstbuf, "\\%c", *src++);
-
-        for (; *src; src++) {
-            if ((special_chars && strchr(special_chars, *src)) ||
-                strchr("'\\", *src) ||
-                (mode == ESCAPE_MODE_FULL && strchr(WHITESPACES, *src)))
-                av_bprintf(&dstbuf, "\\%c", *src);
-            else
-                av_bprint_chars(&dstbuf, *src, 1);
-        }
-
-        if (mode == ESCAPE_MODE_LAZY && strchr(WHITESPACES, dstbuf.str[dstbuf.len-1])) {
-            char c = dstbuf.str[dstbuf.len-1];
-            dstbuf.str[dstbuf.len-1] = '\\';
-            av_bprint_chars(&dstbuf, c, 1);
-        }
-        break;
-
-    case ESCAPE_MODE_QUOTE:
-        /* enclose between '' the string */
-        av_bprint_chars(&dstbuf, '\'', 1);
-        for (; *src; src++) {
-            if (*src == '\'')
-                av_bprintf(&dstbuf, "'\\''");
-            else
-                av_bprint_chars(&dstbuf, *src, 1);
-        }
-        av_bprint_chars(&dstbuf, '\'', 1);
-        break;
-
-    default:
-        /* unknown escape mode */
-        return AVERROR(EINVAL);
-    }
-
-    if (!av_bprint_is_complete(&dstbuf)) {
-        av_bprint_finalize(&dstbuf, NULL);
-        return AVERROR(ENOMEM);
-    } else {
-        av_bprint_finalize(&dstbuf, dst);
-        return 0;
-    }
-}
-
 int main(int argc, char **argv)
 {
     AVBPrint src;
@@ -123,13 +59,14 @@ int main(int argc, char **argv)
     const char *outfilename = NULL, *infilename = NULL;
     FILE *outfile = NULL, *infile = NULL;
     const char *prompt = "=> ";
-    enum EscapeMode escape_mode = ESCAPE_MODE_LAZY;
+    enum AVEscapeMode escape_mode = AV_ESCAPE_MODE_AUTO;
+    int escape_flags = 0;
     int level = 1;
     int echo = 0;
     char *special_chars = NULL;
     int c;
 
-    while ((c = getopt(argc, argv, "ehi:l:o:m:p:s:")) != -1) {
+    while ((c = getopt(argc, argv, "ef:hi:l:o:m:p:s:")) != -1) {
         switch (c) {
         case 'e':
             echo = 1;
@@ -140,6 +77,16 @@ int main(int argc, char **argv)
         case 'i':
             infilename = optarg;
             break;
+        case 'f':
+            if      (!strcmp(optarg, "whitespace")) escape_flags |= AV_ESCAPE_FLAG_WHITESPACE;
+            else if (!strcmp(optarg, "strict"))     escape_flags |= AV_ESCAPE_FLAG_STRICT;
+            else {
+                av_log(NULL, AV_LOG_ERROR,
+                       "Invalid value '%s' for option -f, "
+                       "valid arguments are 'whitespace', and 'strict'\n", optarg);
+                return 1;
+            }
+            break;
         case 'l':
         {
             char *tail;
@@ -154,13 +101,13 @@ int main(int argc, char **argv)
             break;
         }
         case 'm':
-            if      (!strcmp(optarg, "full"))  escape_mode = ESCAPE_MODE_FULL;
-            else if (!strcmp(optarg, "lazy"))  escape_mode = ESCAPE_MODE_LAZY;
-            else if (!strcmp(optarg, "quote")) escape_mode = ESCAPE_MODE_QUOTE;
+            if      (!strcmp(optarg, "auto"))      escape_mode = AV_ESCAPE_MODE_AUTO;
+            else if (!strcmp(optarg, "backslash")) escape_mode = AV_ESCAPE_MODE_BACKSLASH;
+            else if (!strcmp(optarg, "quote"))     escape_mode = AV_ESCAPE_MODE_QUOTE;
             else {
                 av_log(NULL, AV_LOG_ERROR,
                        "Invalid value '%s' for option -m, "
-                       "valid arguments are 'full', 'lazy', 'quote'\n", optarg);
+                       "valid arguments are 'backslash', and 'quote'\n", optarg);
                 return 1;
             }
             break;
@@ -219,7 +166,7 @@ int main(int argc, char **argv)
     /* escape */
     dst_buf = src_buf;
     while (level--) {
-        if (escape(&dst_buf, src_buf, special_chars, escape_mode) < 0) {
+        if (av_escape(&dst_buf, src_buf, special_chars, escape_mode, escape_flags) < 0) {
             av_log(NULL, AV_LOG_ERROR, "Could not escape string\n");
             return 1;
         }