LuaDardo Plus #

A maintained fork of LuaDardo - Lua 5.3 virtual machine written in pure Dart.

Why This Fork? #

The original LuaDardo has been inactive since July 2023 with several critical bugs unfixed. This fork provides:

• Bug fixes for issues #13, #24, #33, #34, #36
• Web platform support - runs on all platforms including browsers
• Async Dart functions - call async Dart code from Lua
• Active maintenance and community support
• 100% Dart - no native dependencies

Fixed Issues #

Installation #

dependencies:
  lua_dardo_plus: ^0.3.0

Example #

import 'package:lua_dardo_plus/lua.dart';

void main() {
  LuaState state = LuaState.newState();
  state.openLibs();
  state.loadString(r'''
a = 10
while a < 20 do
   print("a value is", a)
   a = a + 1
end
''');
  state.call(0, 0);
}

Usage #

The LuaDardo Plus library is compatible with Lua C APIs. For Dart-Lua interoperability, refer to the Lua C API guide.

Dart Calls Lua #

Get Lua variables:

-- test.lua
a = 100
b = 120

LuaState ls = LuaState.newState();
ls.openLibs();
ls.doFile("test.lua");

ls.getGlobal("a");
if (ls.isNumber(-1)) {
  var a = ls.toNumber(-1);
  print("a=$a");
}

ls.getGlobal("b");
if (ls.isNumber(-1)) {
  var b = ls.toNumber(-1);
  print("b=$b");
}

Get Lua table:

-- test.lua
mytable = {k1 = 1, k2 = 2.34, k3 = "test"}

ls.getGlobal("mytable");
ls.getField(-1, "k1");
if (ls.isInteger(-1)) {
  var k1 = ls.toInteger(-1);
}

Call Lua function:

-- test.lua
function myFunc()
    print("myFunc run")
end

ls.doFile("test.lua");
ls.getGlobal("myFunc");
if (ls.isFunction(-1)) {
  ls.pCall(0, 0, 0);
}

Lua Calls Dart #

import 'package:lua_dardo_plus/lua.dart';
import 'dart:math';

// Wrapper function signature: int Function(LuaState ls)
// Return value is the number of returned values
int randomInt(LuaState ls) {
  int max = ls.checkInteger(1);
  ls.pop(1);

  var random = Random();
  var randVal = random.nextInt(max);
  ls.pushInteger(randVal);
  return 1;
}

void main() {
  LuaState state = LuaState.newState();
  state.openLibs();

  state.pushDartFunction(randomInt);
  state.setGlobal('randomInt');

  state.loadString('''
rand_val = randomInt(10)
print('random value is '..rand_val)
''');
  state.call(0, 0);
}

Async Dart Functions #

Call async Dart functions from Lua (v0.3.0+):

import 'package:lua_dardo_plus/lua.dart';

Future<int> fetchData(LuaState ls) async {
  final url = ls.checkString(1);

  // Simulate async operation (e.g., HTTP request)
  await Future.delayed(Duration(seconds: 1));

  ls.pushString('Data from $url');
  return 1; // Number of return values
}

void main() async {
  LuaState state = LuaState.newState();
  state.openLibs();

  // Register async function
  state.registerAsync('fetchData', fetchData);

  // Call from Dart using callAsync
  state.getGlobal('fetchData');
  state.pushString('https://api.example.com');
  await state.callAsync(1, 1);

  print(state.toStr(-1)); // "Data from https://api.example.com"
}

Available async methods:

• registerAsync(name, func) - Register async function as global
• pushDartFunctionAsync(func) - Push async function onto stack
• pushDartClosureAsync(func, nUpvals) - Push async closure with upvalues
• callAsync(nArgs, nResults) - Call function asynchronously
• pCallAsync(nArgs, nResults, errFunc) - Protected async call
• doStringAsync(code) - Execute Lua string asynchronously
• doFileAsync(path) - Execute Lua file asynchronously

Web Platform Support #

LuaDardo Plus works on web platforms (v0.3.0+). The library uses platform abstraction to handle dart:io dependencies:

import 'package:lua_dardo_plus/lua.dart';
import 'package:lua_dardo_plus/src/platform/platform.dart';

void main() {
  // Customize print output (useful for web)
  PlatformServices.instance.printCallback = (s) {
    // Redirect to console, DOM, etc.
    print(s);
  };

  LuaState state = LuaState.newState();
  state.openLibs();
  state.doString('print("Hello from Lua on the web!")');
}

Web limitations:

• os.execute(), os.exit(), os.remove(), os.rename(), os.getenv() throw UnsupportedError
• os.time(), os.clock(), os.date(), os.difftime() work normally
• File loading (doFile, loadFile) not supported on web

Migration from lua_dardo #

Simply update your import:

// Before
import 'package:lua_dardo/lua.dart';

// After
import 'package:lua_dardo_plus/lua.dart';

License #

Apache-2.0 (same as original LuaDardo)

Credits #

• Original author: arcticfox1919
• Fork maintainer: ImL1s