cmdutils: allow storing per-stream/chapter/.... options in a generic way

cmdutils.c

@@ -207,6 +207,7 @@ int parse_option(void *optctx, const char *opt, const char *arg, const OptionDef
 {
     const OptionDef *po;
     int bool_val = 1;
+    int *dstcount;
     void *dst;
 
     po = find_option(options, opt);
@@ -231,7 +232,17 @@ unknown_opt:
 
     /* new-style options contain an offset into optctx, old-style address of
      * a global var*/
-    dst = po->flags & (OPT_OFFSET) ? (uint8_t*)optctx + po->u.off : po->u.dst_ptr;
+    dst = po->flags & (OPT_OFFSET|OPT_SPEC) ? (uint8_t*)optctx + po->u.off : po->u.dst_ptr;
+
+    if (po->flags & OPT_SPEC) {
+        SpecifierOpt **so = dst;
+        char *p = strchr(opt, ':');
+
+        dstcount = (int*)(so + 1);
+        *so = grow_array(*so, sizeof(**so), dstcount, *dstcount + 1);
+        (*so)[*dstcount - 1].specifier = av_strdup(p ? p + 1 : "");
+        dst = &(*so)[*dstcount - 1].u;
+    }
 
     if (po->flags & OPT_STRING) {
         char *str;

cmdutils.h

@@ -108,6 +108,16 @@ double parse_number_or_die(const char *context, const char *numstr, int type, do
  */
 int64_t parse_time_or_die(const char *context, const char *timestr, int is_duration);
 
+typedef struct SpecifierOpt {
+    char *specifier;    /**< stream/chapter/program/... specifier */
+    union {
+        uint8_t *str;
+        int        i;
+        int64_t  i64;
+        float      f;
+    } u;
+} SpecifierOpt;
+
 typedef struct {
     const char *name;
     int flags;
@@ -126,6 +136,9 @@ typedef struct {
 #define OPT_DATA   0x1000
 #define OPT_FUNC2  0x2000
 #define OPT_OFFSET 0x4000       /* option is specified as an offset in a passed optctx */
+#define OPT_SPEC   0x8000       /* option is to be stored in an array of SpecifierOpt.
+                                   Implies OPT_OFFSET. Next element after the offset is
+                                   an int containing element count in the array. */
      union {
         void *dst_ptr;
         int (*func_arg)(const char *, const char *);