feat: support multiple return values from js-functions

Author: quaternion

src/lua-state-context.cpp

@@ -617,6 +617,7 @@ namespace {
     int top_index = lua_gettop(L);
 
     std::vector<napi_value> js_args;
+    js_args.reserve(top_index - 1);
     for (int i = 2; i <= top_index; ++i) {
       auto js_arg = ReadJsValueFromStack(L, env, i);
       js_args.push_back(js_arg);
@@ -625,9 +626,18 @@ namespace {
     // call js function
     Napi::Value js_function_result = js_function_holder->ref->Call(js_args);
 
-    PushJsValueToStack(L, js_function_result);
-
-    return 1;
+    if (js_function_result.IsArray()) {
+      Napi::Array js_function_results = js_function_result.As<Napi::Array>();
+      uint32_t js_function_results_length = js_function_results.Length();
+      for (uint32_t i = 0; i < js_function_results_length; ++i) {
+        Napi::Value result = js_function_results.Get(i);
+        PushJsValueToStack(L, result);
+      }
+      return js_function_results_length;
+    } else {
+      PushJsValueToStack(L, js_function_result);
+      return 1;
+    }
   }
 
   int GcJsFunctionLuaCallback(lua_State* L) {

tests/lua-state.set-global.test.js

@@ -133,5 +133,13 @@ describe(`${LuaState.name}#${LuaState.prototype.setGlobal.name}`, () => {
         'should returns result',
       )
     })
+
+    it('should set function with multiple returns', () => {
+      luaState.setGlobal('func', () => {
+        return [1, 'foo']
+      })
+      luaState.eval(`r1, r2 = func()`)
+      deepStrictEqual(luaState.eval(`return { r1, r2 }`), { 1: 1, 2: 'foo' })
+    })
   })
 })