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Expose insufficient material and repeated position functions

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This commit is contained in:
Sebastian Lague 2023-07-24 22:51:54 +02:00
parent d18b6702f2
commit 188f6f8d3a
1 changed files with 24 additions and 11 deletions
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21
Chess-Challenge/src/API/Board.cs
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@ -168,18 +168,31 @@ namespace ChessChallenge.API
public bool IsInCheckmate() => IsInCheck() && GetLegalMoves().Length == 0;
/// <summary>
/// Test if the current position is a draw due stalemate,
/// 3-fold repetition, insufficient material, or 50-move rule.
/// Test if the current position is a draw due stalemate, repetition, insufficient material, or 50-move rule.
/// Note: this function will return true if the same position has occurred twice on the board (rather than 3 times,
/// which is when the game is actually drawn). This quirk is to help bots avoid repeating positions unnecessarily.
/// </summary>
public bool IsDraw()
{
return IsFiftyMoveDraw() || Arbiter.InsufficentMaterial(board) || IsInStalemate() || IsRepetition();
return IsFiftyMoveDraw() || IsInsufficientMaterial() || IsInStalemate() || IsRepeatedPosition();
bool IsInStalemate() => !IsInCheck() && GetLegalMoves().Length == 0;
bool IsFiftyMoveDraw() => board.currentGameState.fiftyMoveCounter >= 100;
bool IsRepetition() => repetitionHistory.Contains(board.ZobristKey);
}
/// <summary>
/// Test if the current position has occurred at least once before on the board.
/// This includes both positions in the actual game, and positions reached by
/// making moves while the bot is thinking.
/// </summary>
public bool IsRepeatedPosition() => repetitionHistory.Contains(board.ZobristKey);
/// <summary>
/// Test if there are sufficient pieces remaining on the board to potentially deliver checkmate.
/// If not, the game is automatically a draw.
/// </summary>
public bool IsInsufficientMaterial() => Arbiter.InsufficentMaterial(board);
/// <summary>
/// Does the given player still have the right to castle kingside?
/// Note that having the right to castle doesn't necessarily mean castling is legal right now