gobang/lib/flyweight/chess_flyweight_factory.dart

import 'package:gobang/flyweight/chess.dart';

/// 棋子享元工厂（单例）
class ChessFlyweightFactory {
  ChessFlyweightFactory._();

  static final ChessFlyweightFactory instance = ChessFlyweightFactory._();

  static ChessFlyweightFactory getInstance() => instance;

  final Map<String, Chess> _cache = {};

  Chess getChess(String type) {
    return _cache.putIfAbsent(type, () {
      switch (type) {
        case 'white':
          return WhiteChess();
        case 'black':
        default:
          return BlackChess();
      }
    });
  }
}