options: handle choice -> flag fallback automatically

In the past it happened quite often that flag options (yes/no) were
changed to choice options (yes/no/some more). The problem with this was
that while flag options don't need a parameter, this wasn't the case
with choice options. A hack was introduced to compensate for this:
setting M_OPT_OPTIONAL_PARAM on the option, and an empty string ("") was
added as choice, so that the choice could be used like a flag. So, for
example, "--mute" would set the choice "".

Fix this by 1. not requiring a parameter if there's a "yes" choice, and
2. redirect an empty parameter to "yes". The effect is that a choice
option with the choices ["yes", "no"] is pretty much equivalent to a
flag option.

options/m_option.c

@@ -74,9 +74,15 @@ char *m_option_strerror(int code)
 
 int m_option_required_params(const m_option_t *opt)
 {
-    if (((opt->flags & M_OPT_OPTIONAL_PARAM) ||
-            (opt->type->flags & M_OPT_TYPE_OPTIONAL_PARAM)))
+    if (opt->type->flags & M_OPT_TYPE_OPTIONAL_PARAM)
         return 0;
+    if (opt->type == &m_option_type_choice) {
+        struct m_opt_choice_alternatives *alt;
+        for (alt = opt->priv; alt->name; alt++) {
+            if (strcmp(alt->name, "yes") == 0)
+                return 0;
+        }
+    }
     return 1;
 }
 
@@ -535,9 +541,17 @@ static int parse_choice(struct mp_log *log, const struct m_option *opt,
                         struct bstr name, struct bstr param, void *dst)
 {
     struct m_opt_choice_alternatives *alt = opt->priv;
-    for ( ; alt->name; alt++)
+    for ( ; alt->name; alt++) {
         if (!bstrcmp0(param, alt->name))
             break;
+    }
+    if (!alt->name && param.len == 0) {
+        // allow flag-style options, e.g. "--mute" implies "--mute=yes"
+        for (alt = opt->priv; alt->name; alt++) {
+            if (!strcmp("yes", alt->name))
+                break;
+        }
+    }
     if (!alt->name) {
         if (param.len == 0)
             return M_OPT_MISSING_PARAM;

options/m_option.h

@@ -358,9 +358,6 @@ struct m_option {
 // The option should be set during command line pre-parsing
 #define M_OPT_PRE_PARSE         (1 << 6)
 
-// See M_OPT_TYPE_OPTIONAL_PARAM.
-#define M_OPT_OPTIONAL_PARAM    (1 << 10)
-
 // The option expects a file name (or a list of file names)
 #define M_OPT_FILE              (1 << 11)
 

options/options.c

@@ -189,9 +189,9 @@ const m_option_t mp_opts[] = {
     OPT_TIME("ab-loop-b", ab_loop[1], 0, .min = MP_NOPTS_VALUE),
 
     OPT_FLAG("pause", pause, M_OPT_FIXED),
-    OPT_CHOICE("keep-open", keep_open, M_OPT_OPTIONAL_PARAM,
+    OPT_CHOICE("keep-open", keep_open, 0,
                ({"no", 0},
-                {"yes", 1}, {"", 1},
+                {"yes", 1},
                 {"always", 2})),
 
     OPT_CHOICE("index", index_mode, 0, ({"default", 1}, {"recreate", 0})),
@@ -274,10 +274,10 @@ const m_option_t mp_opts[] = {
     OPT_SETTINGSLIST("vf-defaults", vf_defs, 0, &vf_obj_list),
     OPT_SETTINGSLIST("vf*", vf_settings, 0, &vf_obj_list),
 
-    OPT_CHOICE("deinterlace", deinterlace, M_OPT_OPTIONAL_PARAM,
+    OPT_CHOICE("deinterlace", deinterlace, 0,
                ({"auto", -1},
                 {"no", 0},
-                {"yes", 1}, {"", 1})),
+                {"yes", 1})),
 
     OPT_STRING("ad", audio_decoders, 0),
     OPT_STRING("vd", video_decoders, 0),
@@ -386,14 +386,14 @@ const m_option_t mp_opts[] = {
                 {"auto", SOFTVOL_AUTO})),
     OPT_FLOATRANGE("softvol-max", softvol_max, 0, 10, 10000),
     OPT_FLOATRANGE("volume", mixer_init_volume, 0, -1, 100),
-    OPT_CHOICE("mute", mixer_init_mute, M_OPT_OPTIONAL_PARAM,
+    OPT_CHOICE("mute", mixer_init_mute, 0,
                ({"auto", -1},
                 {"no", 0},
-                {"yes", 1}, {"", 1})),
+                {"yes", 1})),
     OPT_STRING("volume-restore-data", mixer_restore_volume_data, 0),
-    OPT_CHOICE("gapless-audio", gapless_audio, M_OPT_OPTIONAL_PARAM,
+    OPT_CHOICE("gapless-audio", gapless_audio, 0,
                ({"no", 0},
-                {"yes", 1}, {"", 1},
+                {"yes", 1},
                 {"weak", -1})),
     OPT_DOUBLE("audio-buffer", audio_buffer, M_OPT_MIN | M_OPT_MAX,
                .min = 0, .max = 10),
@@ -505,8 +505,9 @@ const m_option_t mp_opts[] = {
                       ({"no", 1},
                        {"inf", -1},
                        {"force", -2})),
-    OPT_CHOICE_OR_INT("loop-file", loop_file, M_OPT_OPTIONAL_PARAM, 0, 10000,
-                      ({"yes", -1}, {"", -1}, {"no", 0}, // compat
+    OPT_CHOICE_OR_INT("loop-file", loop_file, 0, 0, 10000,
+                      ({"no", 0},
+                       {"yes", -1},
                        {"inf", -1})),
 
     OPT_FLAG("resume-playback", position_resume, 0),
@@ -553,11 +554,10 @@ const m_option_t mp_opts[] = {
     OPT_STRING("osd-msg2", osd_msg[1], 0),
     OPT_STRING("osd-msg3", osd_msg[2], 0),
 
-    OPT_CHOICE("idle", player_idle_mode, M_OPT_OPTIONAL_PARAM,
+    OPT_CHOICE("idle", player_idle_mode, 0,
                ({"no",   0},
                 {"once", 1},
-                {"yes",  2},
-                {"",     2})),
+                {"yes",  2})),
 
     OPT_FLAG("input-terminal", consolecontrols, CONF_GLOBAL),
 

video/out/gl_video.c

@@ -398,9 +398,9 @@ const struct m_sub_options gl_video_conf = {
                    ({"auto",   MP_CHROMA_AUTO},
                     {"center", MP_CHROMA_CENTER},
                     {"left",   MP_CHROMA_LEFT})),
-        OPT_CHOICE("alpha", alpha_mode, M_OPT_OPTIONAL_PARAM,
+        OPT_CHOICE("alpha", alpha_mode, 0,
                    ({"no", 0},
-                    {"yes", 1}, {"", 1},
+                    {"yes", 1},
                     {"blend", 2})),
         OPT_FLAG("rectangle-textures", use_rectangle, 0),
         OPT_COLOR("background", background, 0),