Class FunctionTypeExtension

src/type-extensions/function.ts:25–235

}

class FunctionTypeExtension extends TypeExtension<FunctionType, FunctionDecoration> {
    private readonly functionRegistry =
        typeof FinalizationRegistry !== 'undefined'
            ? new FinalizationRegistry((func: number) => {
                  if (!this.thread.isClosed()) {
                      this.thread.lua.luaL_unref(this.thread.address, LUA_REGISTRYINDEX, func)
                  }
              })
            : undefined

    private gcPointer: number
    private functionWrapper: number
    private callbackContext: Thread
    private callbackContextIndex: number
    private options?: FunctionTypeExtensionOptions

    public constructor(thread: Global, options?: FunctionTypeExtensionOptions) {
        super(thread, 'js_function')

        this.options = options
        // Create a thread off of the global thread to be used to create function call threads without
        // interfering with the global context. This creates a callback context that will always exist
        // even if the thread that called getValue() has been destroyed.
        this.callbackContext = thread.newThread()
        // Pops it from the global stack but keeps it alive
        this.callbackContextIndex = this.thread.lua.luaL_ref(thread.address, LUA_REGISTRYINDEX)

        if (!this.functionRegistry) {
            console.warn('FunctionTypeExtension: FinalizationRegistry not found. Memory leaks likely.')
        }

        this.gcPointer = thread.lua.module.addFunction((calledL: LuaState) => {
            // Throws a lua error which does a jump if it does not match.
            thread.lua.luaL_checkudata(calledL, 1, this.name)

            const userDataPointer = thread.lua.luaL_checkudata(calledL, 1, this.name)
            const referencePointer = thread.lua.module.getValue(userDataPointer, '*')
            thread.lua.unref(referencePointer)

            return LuaReturn.Ok
        }, 'ii')

        // Creates metatable if it doesn't exist, always pushes it onto the stack.
        if (thread.lua.luaL_newmetatable(thread.address, this.name)) {
            thread.lua.lua_pushstring(thread.address, '__gc')
            thread.lua.lua_pushcclosure(thread.address, this.gcPointer, 0)
            thread.lua.lua_settable(thread.address, -3)

            thread.lua.lua_pushstring(thread.address, '__metatable')
            thread.lua.lua_pushstring(thread.address, 'protected metatable')
            thread.lua.lua_settable(thread.address, -3)
        }
        // Pop the metatable from the stack.
        thread.lua.lua_pop(thread.address, 1)

        this.functionWrapper = thread.lua.module.addFunction((calledL: LuaState) => {
            const calledThread = thread.stateToThread(calledL)