client API: add mpv_command_ret

This change adds a version of `mpv_command` that also returns a result.
The main rationale behind this is `mpv_command_node` requires defining
multiple structs before you can even use it, which results in a pretty
painful to use interface just to get the result from a command.

There isn't really a good name for this function, so I'm open to
suggestions on a better name for it.

libmpv/client.h

@@ -969,6 +969,22 @@ int mpv_command(mpv_handle *ctx, const char **args);
  */
 int mpv_command_node(mpv_handle *ctx, mpv_node *args, mpv_node *result);
 
+/**
+ * This is essentially identical to mpv_command() but it also returns a result.
+ *
+ * Does not use OSD and string expansion by default.
+ *
+ * @param[in] args NULL-terminated list of strings. Usually, the first item
+ *                 is the command, and the following items are arguments.
+ * @param[out] result Optional, pass NULL if unused. If not NULL, and if the
+ *                    function succeeds, this is set to command-specific return
+ *                    data. You must call mpv_free_node_contents() to free it
+ *                    (again, only if the command actually succeeds).
+ *                    Not many commands actually use this at all.
+ * @return error code (the result parameter is not set on error)
+ */
+int mpv_command_ret(mpv_handle *ctx, const char **args, mpv_node *result);
+
 /**
  * Same as mpv_command, but use input.conf parsing for splitting arguments.
  * This is slightly simpler, but also more error prone, since arguments may

libmpv/mpv.def

@@ -5,6 +5,7 @@ mpv_command
 mpv_command_async
 mpv_command_node
 mpv_command_node_async
+mpv_command_ret
 mpv_command_string
 mpv_create
 mpv_create_client

player/client.c

@@ -1087,6 +1087,15 @@ int mpv_command_node(mpv_handle *ctx, mpv_node *args, mpv_node *result)
     return r;
 }
 
+int mpv_command_ret(mpv_handle *ctx, const char **args, mpv_node *result)
+{
+    struct mpv_node rn = {.format = MPV_FORMAT_NONE};
+    int r = run_client_command(ctx, mp_input_parse_cmd_strv(ctx->log, args), &rn);
+    if (result && r >= 0)
+        *result = rn;
+    return r;
+}
+
 int mpv_command_string(mpv_handle *ctx, const char *args)
 {
     return run_client_command(ctx,