Add initial Lua scripting support

This is preliminary. There are still tons of issues, and any aspect
of scripting may change in the future. I decided to merge this
(preliminary) work now because it makes it easier to develop it, not
because it's done. lua.rst is clear enough about it (plus some
sarcasm).

This requires linking to Lua. Lua has no official pkg-config file, but
there are distribution specific .pc files, all with different names.
Adding a non-pkg-config based configure test was considered, but we'd
rather not.

One major complication is that libquvi links against Lua too, and if
the Lua version is different from mpv's, you will get a crash as soon
as libquvi uses Lua. (libquvi by design always runs when a file is
opened.) I would consider this the problem of distros and whoever
builds mpv, but to make things easier for users, we add a terrible
runtime test to the configure script, which probes whether libquvi
will crash. This is disabled when cross-compiling, but in that case
we hope the user knows what he is doing.

2 files changed, 8 insertions, 0 deletions

diff --git a/mpvcore/input/input.c b/mpvcore/input/input.c
index 902aa52b47..f624b8f5dd 100644
--- a/mpvcore/input/input.c
+++ b/mpvcore/input/input.c
@@ -229,6 +229,8 @@ static const mp_cmd_t mp_cmds[] = {
 
   { MP_CMD_VO_CMDLINE, "vo_cmdline", { ARG_STRING } },
 
+  { MP_CMD_SCRIPT_DISPATCH, "script_dispatch", { ARG_STRING, ARG_INT } },
+
   {0}
 };
 
@@ -528,6 +530,7 @@ struct input_ctx {
     // Autorepeat stuff
     short ar_state;
     int64_t last_ar;
+
     // Autorepeat config
     unsigned int ar_delay;
     unsigned int ar_rate;
@@ -1455,6 +1458,8 @@ static void remove_key_down(struct input_ctx *ictx, int code)
 static bool key_updown_ok(enum mp_command_type cmd)
 {
     switch (cmd) {
+    case MP_CMD_SCRIPT_DISPATCH:
+        return true;
     default:
         return false;
     }
diff --git a/mpvcore/input/input.h b/mpvcore/input/input.h
index f3ea895395..639f069a9c 100644
--- a/mpvcore/input/input.h
+++ b/mpvcore/input/input.h
@@ -85,6 +85,9 @@ enum mp_command_type {
     /// Video output commands
     MP_CMD_VO_CMDLINE,
 
+    /// Internal for Lua scripts
+    MP_CMD_SCRIPT_DISPATCH,
+
     // Internal
     MP_CMD_COMMAND_LIST, // list of sub-commands in args[0].v.p
 };