command, lua: add a way to share data between scripts

Very primitive and dumb, but fulfils its purpose for the next commits.

I chose this specific implementation because it has the lowest footprint
in command.c, without resorting to crazy hacks such as sending messages
between scripts (which would be hard to coordinate especially on
startup).

2 files changed, 55 insertions, 0 deletions

diff --git a/player/command.c b/player/command.c
index 8576e36da7..32e4e3dfea 100644
--- a/player/command.c
+++ b/player/command.c
@@ -102,6 +102,12 @@ struct command_ctx {
     struct ao_hotplug *hotplug;
 
     struct mp_cmd_ctx *cache_dump_cmd; // in progress cache dumping
+
+    char **script_props;
+};
+
+static const struct m_option script_props_type = {
+    .type = &m_option_type_keyvalue_list
 };
 
 struct overlay {
@@ -3217,6 +3223,27 @@ static int mp_property_bindings(void *ctx, struct m_property *prop,
     return M_PROPERTY_NOT_IMPLEMENTED;
 }
 
+
+static int mp_property_script_props(void *ctx, struct m_property *prop,
+                                    int action, void *arg)
+{
+    MPContext *mpctx = ctx;
+    struct command_ctx *cmd = mpctx->command_ctx;
+    switch (action) {
+    case M_PROPERTY_GET_TYPE:
+        *(struct m_option *)arg = script_props_type;
+        return M_PROPERTY_OK;
+    case M_PROPERTY_GET:
+        m_option_copy(&script_props_type, arg, &cmd->script_props);
+        return M_PROPERTY_OK;
+    case M_PROPERTY_SET:
+        m_option_copy(&script_props_type, &cmd->script_props, arg);
+        mp_notify_property(mpctx, prop->name);
+        return M_PROPERTY_OK;
+    }
+    return M_PROPERTY_NOT_IMPLEMENTED;
+}
+
 // Redirect a property name to another
 #define M_PROPERTY_ALIAS(name, real_property) \
     {(name), mp_property_alias, .priv = (real_property)}
@@ -3391,6 +3418,8 @@ static const struct m_property mp_properties_base[] = {
     {"command-list", mp_property_commands},
     {"input-bindings", mp_property_bindings},
 
+    {"shared-script-properties", mp_property_script_props},
+
     M_PROPERTY_ALIAS("video", "vid"),
     M_PROPERTY_ALIAS("audio", "aid"),
     M_PROPERTY_ALIAS("sub", "sid"),
@@ -5856,6 +5885,8 @@ void command_uninit(struct MPContext *mpctx)
     overlay_uninit(mpctx);
     ao_hotplug_destroy(ctx->hotplug);
 
+    m_option_free(&script_props_type, &ctx->script_props);
+
     talloc_free(mpctx->command_ctx);
     mpctx->command_ctx = NULL;
 }
diff --git a/player/lua/defaults.lua b/player/lua/defaults.lua
index f2983e8dc3..29e513f4ea 100644
--- a/player/lua/defaults.lua
+++ b/player/lua/defaults.lua
@@ -676,4 +676,28 @@ function mp_utils.subprocess_detached(t)
     mp.commandv("run", unpack(t.args))
 end
 
+function mp_utils.shared_script_property_set(name, value)
+    if value ~= nil then
+        -- no such thing as change-list with mpv_node, so build a string value
+        mp.commandv("change-list", "shared-script-properties", "append",
+                    name .. "=" .. value)
+    else
+        mp.commandv("change-list", "shared-script-properties", "remove", name)
+    end
+end
+
+function mp_utils.shared_script_property_get(name)
+    local map = mp.get_property_native("shared-script-properties")
+    return map and map[name]
+end
+
+-- cb(name, value) on change and on init
+function mp_utils.shared_script_property_observe(name, cb)
+    -- it's _very_ wasteful to observe the mpv core "super" property for every
+    -- shared sub-property, but then again you shouldn't use this
+    mp.observe_property("shared-script-properties", "native", function(_, val)
+        cb(name, val and val[name])
+    end)
+end
+
 return {}