1. 技术文章
  2. Object Oriented Design for a Chess game [closed]

Object Oriented Design for a Chess game [closed]

由 偶尔善良 提交于 2019-11-29 19:02:10

I actually just wrote a full C# implementation of a chess board, pieces, rules, etc. Here's roughly how I modeled it (actual implementation removed since I don't want to take all the fun out of your coding):

public enum PieceType {
    None, Pawn, Knight, Bishop, Rook, Queen, King
}

public enum PieceColor {
    White, Black
}

public struct Piece {
    public PieceType Type { get; set; }
    public PieceColor Color { get; set; }
}

public struct Square {
    public int X { get; set; }
    public int Y { get; set; }

    public static implicit operator Square(string str) {
        // Parses strings like "a1" so you can write "a1" in code instead
        // of new Square(0, 0)
    }
}

public class Board {
    private Piece[,] board;

    public Piece this[Square square] { get; set; }

    public Board Clone() { ... }
}

public class Move {
    public Square From { get; }
    public Square To { get; }
    public Piece PieceMoved { get; }
    public Piece PieceCaptured { get; }
    public PieceType Promotion { get; }
    public string AlgebraicNotation { get; }
}

public class Game {
    public Board Board { get; }
    public IList<Move> Movelist { get; }
    public PieceType Turn { get; set; }
    public Square? DoublePawnPush { get; set; } // Used for tracking valid en passant captures
    public int Halfmoves { get; set; }

    public bool CanWhiteCastleA { get; set; }
    public bool CanWhiteCastleH { get; set; }
    public bool CanBlackCastleA { get; set; }
    public bool CanBlackCastleH { get; set; }
}

public interface IGameRules {
    // ....
}

The basic idea is that Game/Board/etc simply store the state of the game. You can manipulate them to e.g. set up a position, if that's what you want. I have a class that implements my IGameRules interface that is responsible for:

  • Determining what moves are valid, including castling and en passant.
  • Determining if a specific move is valid.
  • Determining when players are in check/checkmate/stalemate.
  • Executing moves.

Separating the rules from the game/board classes also means you can implement variants relatively easily. All methods of the rules interface take a Game object which they can inspect to determine which moves are valid.

Note that I do not store player information on Game. I have a separate class Table that is responsible for storing game metadata such as who was playing, when the game took place, etc.

EDIT: Note that the purpose of this answer isn't really to give you template code you can fill out -- my code actually has a bit more information stored on each item, more methods, etc. The purpose is to guide you towards the goal you're trying to achieve.

Here is my idea, for a fairly basic chess game : 

class GameBoard {
 IPiece config[8][8];  

 init {
  createAndPlacePieces("Black");
  createAndPlacePieces("White");
  setTurn("Black");

 }

 createAndPlacePieces(color) {
   //generate pieces using a factory method
   //for e.g. config[1][0] = PieceFactory("Pawn",color);
 }

 setTurn(color) {
   turn = color;
 }

 move(fromPt,toPt) {
  if(getPcAt(fromPt).color == turn) {
    toPtHasOppositeColorPiece = getPcAt(toPt) != null && getPcAt(toPt).color != turn;
    possiblePath = getPcAt(fromPt).generatePossiblePath(fromPt,toPt,toPtHasOppositeColorPiece);
   if(possiblePath != NULL) {
      traversePath();
      changeTurn();
   }
  }
 } 

}

Interface IPiece {
  function generatePossiblePath(fromPt,toPt,toPtHasEnemy);
}

class PawnPiece implements IPiece{
  function generatePossiblePath(fromPt,toPt,toPtHasEnemy) {
    return an array of points if such a path is possible
    else return null;
  }
}

class ElephantPiece implements IPiece {....}

I recently created a chess program in PHP (website click here, source click here) and I made it object oriented. Here are the classes I used.

  • ChessRulebook (static) - I put all my generate_legal_moves() code in here. That method is given a board, whose turn it is, and some variables to set the level of detail of the output, and it generates all the legal moves for that position. It returns a list of ChessMoves.
  • ChessMove - Stores everything needed to create algebraic notation, including starting square, ending square, color, piece type, capture, check, checkmate, promotion piece type, and en passant. Optional additional variables include disambiguation (for moves like Rae4), castling, and board.
  • ChessBoard - Stores the same information as a Chess FEN, including an 8x8 array representing the squares and storing the ChessPieces, whose turn it is, en passant target square, castling rights, halfmove clock, and fullmove clock.
  • ChessPiece - Stores piece type, color, square, and piece value (for example, pawn = 1, knight = 3, rook = 5, etc.)
  • ChessSquare - Stores the rank and file, as ints.

I am currently trying to turn this code into a chess A.I., so it needs to be FAST. I've optimized the generate_legal_moves() function from 1500ms to 8ms, and am still working on it. Lessons I learned from that are...

  • Do not store an entire ChessBoard in every ChessMove by default. Only store the board in the move when needed.
  • Use primitive types such as int when possible. That is why ChessSquare stores rank and file as int, rather than also storing an alphanumeric string with human readable chess square notation such as "a4".
  • The program creates tens of thousands of ChessSquares when searching the move tree. I will probably refactor the program to not use ChessSquares, which should give a speed boost.
  • Do not calculate any unnecessary variables in your classes. Originally, calculating the FEN in each of my ChessBoards was really killing the program's speed. I had to find this out with a profiler.

I know this is old, but hopefully it helps somebody. Good luck!

标签
chess
oop
易学教程内所有资源均来自网络或用户发布的内容，如有违反法律规定的内容欢迎反馈！
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!