Add KeyEventResult enum and support passthrough (filter) mode

Author: buzztaiki

src/addonloader/base.lua

@@ -120,10 +120,23 @@ local oldsetCurrentInputMethod=fcitx.setCurrentInputMethod
 local function setCurrentInputMethod(name,local_im)
     if(local_im == nil) then
         local_im = false
-    end    
+    end
     oldsetCurrentInputMethod(name,local_im)
 end
 
 fcitx.setCurrentInputMethod = setCurrentInputMethod
 
+--- Result of key event handler. It represents the action to be taken
+-- after a fcitx.EventType.KeyEvent handler is executed.
+-- @table KeyEventResult
+-- @field NotHandled Let Fcitx5 continue its normal processing. Equivalent to returning `false`.
+-- @field Handled Fcitx5 handles the event and consumes it. Equivalent to returning `true`.
+-- @field Passthrough Fcitx5 will not process this event and will let it pass through to the application.
+local KeyEventResult = {
+    NotHandled = 0,
+    Handled = 1,
+    Passthrough = 2,
+}
+fcitx.KeyEventResult = KeyEventResult
+
 return fcitx

src/addonloader/luaaddonstate.cpp

@@ -262,9 +262,25 @@ std::tuple<int> LuaAddonState::watchEventImpl(int eventType,
                 return 3;
             },
             [](std::unique_ptr<LuaState> &state, KeyEvent &event) {
-                auto b = lua_toboolean(state, -1);
-                if (b) {
-                    event.filterAndAccept();
+                if (lua_isinteger(state, -1)) {
+                    auto result = lua_tointeger(state, -1);
+                    switch (static_cast<KeyEventResult>(result)) {
+                    case KeyEventResult::NotHandled:
+                        break;
+                    case KeyEventResult::Passthrough:
+                        event.filter();
+                        break;
+                    case KeyEventResult::Handled:
+                        event.filterAndAccept();
+                        break;
+                    default:
+                        FCITX_LUA_ERROR() << "invalid KeyEventResult: " << result;
+                    }
+                } else {
+                    auto b = lua_toboolean(state, -1);
+                    if (b) {
+                        event.filterAndAccept();
+                    }
                 }
             });
         break;

src/addonloader/luaaddonstate.h

@@ -95,6 +95,12 @@ class Converter {
     ScopedConnection connection_;
 };
 
+enum class KeyEventResult {
+    NotHandled,
+    Handled,
+    Passthrough,
+};
+
 class LuaAddonState {
 public:
     LuaAddonState(Library *luaLibrary, const std::string &name,

src/addonloader/luafunc.h

@@ -23,6 +23,7 @@ FOREACH_LUA_FUNCTION(lua_pushstring)
 FOREACH_LUA_FUNCTION(lua_pushlstring)
 FOREACH_LUA_FUNCTION(lua_type)
 FOREACH_LUA_FUNCTION(lua_gettable)
+FOREACH_LUA_FUNCTION(lua_isinteger)
 FOREACH_LUA_FUNCTION(lua_tointegerx)
 FOREACH_LUA_FUNCTION(lua_pushnil)
 FOREACH_LUA_FUNCTION(lua_next)