multistockfish

Multiple flavors of Stockfish Engine.

This plugin provides the following Stockfish engines:

• Official Stockfish engine for chess and chess 960
• Fairy-Stockfish for chess variants

Usage

Init engine

Warning

Only one instance can be created at a time. The Stockfish() constructor will throw a StateError if called while another instance is running.

Note

When using the StockfishFlavor.chess flavor, you need to download the .nnue files before starting an evaluation, since it is not embedded in the binary.

import 'package:multistockfish/multistockfish.dart';

// create a new instance
final stockfish = Stockfish();

// state is a ValueListenable<StockfishState>
print(stockfish.state.value); # StockfishState.starting

// the engine takes a few moment to start
await Future.delayed(...)
print(stockfish.state.value); # StockfishState.ready

UCI command

Wait until the state is ready before sending commands.

stockfish.stdin = 'isready';
stockfish.stdin = 'go movetime 3000';
stockfish.stdin = 'go infinite';
stockfish.stdin = 'stop';

Engine output is directed to a Stream<String>, add a listener to process results.

stockfish.stdout.listen((line) {
  // do something useful
  print(line);
});

Dispose / Hot reload

There are two active isolates when Stockfish engine is running. That interferes with Flutter's hot reload feature so you need to dispose it before attempting to reload.

// sends the UCI quit command
stockfish.stdin = 'quit';

// or even easier...
stockfish.dispose();