private static IEnumerable <SquareCoordinate> GetPawnMobility(SquareCoordinate square, Board board, Color pieceColor)
{
var ret = new List <SquareCoordinate>();
SquareCoordinate?allowedSquare = null;
if (DoubleForwardMoveAllowed(board, pieceColor, square, out allowedSquare))
{
ret.Add(allowedSquare.Value);
}
if (SingleForwardMoveAllowed(board, pieceColor, square, out allowedSquare))
{
ret.Add(allowedSquare.Value);
}
if (IsPawnCaptureAllowed(board, pieceColor, square, square.File - 1, out allowedSquare))
{
ret.Add(allowedSquare.Value);
}
if (IsPawnCaptureAllowed(board, pieceColor, square, square.File + 1, out allowedSquare))
{
ret.Add(allowedSquare.Value);
}
return(ret);
}
private bool IsNotCheckOnKingMove(Board board, SquareCoordinate startingCoordinate, SquareCoordinate endingCoordinate, Color kingColor)
{
return(!board.IsControlledByColor(endingCoordinate, kingColor.OpponentColor) &&
!board.IsInOpponentControlAfterMove(board[startingCoordinate],
board[endingCoordinate],
board[endingCoordinate]));
}
private static void TryAddSquare(List <SquareCoordinate> ret,
SquareCoordinate startingSquare,
int newRank,
int newFile,
Board board,
Color pieceColor,
SquareInfluenceType availabilityType)
{
if (!IsValidPosition(newRank, newFile))
{
return;
}
var newSquare = new SquareCoordinate(newRank, newFile);
switch (availabilityType)
{
case SquareInfluenceType.Control:
ret.Add(newSquare);
break;
case SquareInfluenceType.Mobility:
if (IsInPieceMobility(board, startingSquare, newSquare, pieceColor))
{
ret.Add(newSquare);
}
break;
default:
throw new NotImplementedException();
}
}
private static IEnumerable <SquareCoordinate> GetStraightInBetweenPosition(SquareCoordinate startingCoordinate, SquareCoordinate endingCoordinate)
{
var ret = new List <SquareCoordinate>();
var fileShift = endingCoordinate.File - startingCoordinate.File;
if (fileShift != 0)
{
var shiftDirection = Math.Sign(fileShift);
var shiftAbs = Math.Abs(fileShift);
for (int i = 1; i < shiftAbs; i++)
{
var newFile = startingCoordinate.File + (shiftDirection * i);
ret.Add(new SquareCoordinate(startingCoordinate.Rank, newFile));
}
}
else
{
var rankShift = endingCoordinate.Rank - startingCoordinate.Rank;
var shiftDirection = Math.Sign(rankShift);
var shiftAbs = Math.Abs(rankShift);
for (int i = 1; i < shiftAbs; i++)
{
var newRank = startingCoordinate.Rank + (shiftDirection * i);
ret.Add(new SquareCoordinate(newRank, startingCoordinate.File));
}
}
return(ret);
}
private static bool EnPassantAllowed(Board board, Color color, SquareCoordinate square, out SquareCoordinate?allowedSquare)
{
if (square.Rank == color.EnPassantStartingRank)
{
var lastMove = board.GetLastMove();
if (lastMove != null)
{
var lastMoveEnPassantInfo = lastMove.GetAllowEnPassantOnNextMoveInfo();
if (lastMoveEnPassantInfo.AllowEnPassant)
{
var leftCaptureFile = square.File - 1;
var rightCaptureFile = square.File + 1;
if (lastMoveEnPassantInfo.IsEnPassantFile(leftCaptureFile))
{
allowedSquare = new SquareCoordinate(color.EnPassantStartingRank, leftCaptureFile);
return(true);
}
else if (lastMoveEnPassantInfo.IsEnPassantFile(rightCaptureFile))
{
allowedSquare = new SquareCoordinate(color.EnPassantStartingRank, rightCaptureFile);
return(true);
}
}
}
}
allowedSquare = null;
return(false);
}
internal static bool IsOnTwoOneL(this SquareCoordinate startingCoordinate, SquareCoordinate endingCoordinate)
{
var rankIncrement = Math.Abs(startingCoordinate.Rank - endingCoordinate.Rank);
var fileIncrement = Math.Abs(startingCoordinate.File - endingCoordinate.File);
return(IsATwoOneL(rankIncrement, fileIncrement) ||
IsATwoOneL(fileIncrement, rankIncrement));
}
private bool IsNotBreakingAbsolutePin(Board board, SquareCoordinate startingCoordinate, SquareCoordinate endingCoordinate, Color movingSide)
{
var kingPosition = board.GetKingSquare(movingSide);
return(!board.IsInOpponentControlAfterMove(board[startingCoordinate],
board[endingCoordinate],
kingPosition));
}
internal static bool IsKingValidMove(SquareCoordinate startingCoordinate, SquareCoordinate endingCoordinate)
{
var rankDiff = Math.Abs(startingCoordinate.Rank - endingCoordinate.Rank);
var fileDiff = Math.Abs(startingCoordinate.File - endingCoordinate.File);
return((rankDiff != 0 || fileDiff != 0) &&
(rankDiff == 1 || rankDiff == 0) &&
(fileDiff == 1 || fileDiff == 0));
}
internal ThreefoldRepetitionPositionUnit(SquareCoordinate startingSquare,
SquareCoordinate endingSquare,
Piece piece,
Color nextTurn)
{
_startingSquare = startingSquare;
_endingSquare = endingSquare;
_piece = piece;
_nextTurn = nextTurn;
}
private static bool SingleForwardMoveAllowed(Board board, Color color, SquareCoordinate square, out SquareCoordinate?allowedSquare)
{
var singleRankMove = square.Rank + color.MovingDirection;
var isAllowed = !board.IsAnyPieceInSquare(singleRankMove, square.File) &&
IsValidPosition(singleRankMove, square.File);
allowedSquare = isAllowed
? new SquareCoordinate(singleRankMove, square.File)
: (SquareCoordinate?)null;
return(isAllowed);
}
internal static bool IsOnDiagonal(this SquareCoordinate startingCoordinate, SquareCoordinate endingCoordinate)
{
var rankIncrement = startingCoordinate.Rank - endingCoordinate.Rank;
var fileIncrement = startingCoordinate.File - endingCoordinate.File;
if (fileIncrement == 0)
{
return(false);
}
return(fileIncrement != 0 &&
Math.Abs((double)rankIncrement / fileIncrement) == 1.00);
}
private static bool IsPawnCaptureAllowed(Board board, Color color, SquareCoordinate square, int captureFile, out SquareCoordinate?allowedSquare)
{
var endingRank = square.Rank + color.MovingDirection;
var isAllowed = IsValidPosition(square.Rank, captureFile) &&
board.IsAnyOpponentPieceInSquare(new SquareCoordinate(endingRank, captureFile), color);
allowedSquare = isAllowed
? new SquareCoordinate(endingRank, captureFile)
: (SquareCoordinate?)null;
return(isAllowed);
}
internal static IEnumerable <SquareCoordinate> GetKingControl(SquareCoordinate startingCoordinate)
{
var ret = new List <SquareCoordinate>();
SquareCoordinate?newPos = null;
//Old square
ret.Add(startingCoordinate);
//Upper left
if (TryGetNewPosition(startingCoordinate.Rank + 1, startingCoordinate.File - 1, out newPos))
{
ret.Add(newPos.Value);
}
//Upper middle
if (TryGetNewPosition(startingCoordinate.Rank + 1, startingCoordinate.File, out newPos))
{
ret.Add(newPos.Value);
}
//Upper right
if (TryGetNewPosition(startingCoordinate.Rank + 1, startingCoordinate.File + 1, out newPos))
{
ret.Add(newPos.Value);
}
//Middle right
if (TryGetNewPosition(startingCoordinate.Rank, startingCoordinate.File + 1, out newPos))
{
ret.Add(newPos.Value);
}
//Middle left
if (TryGetNewPosition(startingCoordinate.Rank, startingCoordinate.File - 1, out newPos))
{
ret.Add(newPos.Value);
}
//Bottom right
if (TryGetNewPosition(startingCoordinate.Rank - 1, startingCoordinate.File + 1, out newPos))
{
ret.Add(newPos.Value);
}
//Bottom middle
if (TryGetNewPosition(startingCoordinate.Rank - 1, startingCoordinate.File, out newPos))
{
ret.Add(newPos.Value);
}
//Bottom left
if (TryGetNewPosition(startingCoordinate.Rank - 1, startingCoordinate.File - 1, out newPos))
{
ret.Add(newPos.Value);
}
return(ret);
}
internal static IEnumerable <SquareCoordinate> GetPawnAvailability(SquareCoordinate startingCoordinate, Board board, Color pieceColor, SquareInfluenceType availabilityType)
{
switch (availabilityType)
{
case SquareInfluenceType.Control:
return(GetPawnControl(startingCoordinate, board, pieceColor));
case SquareInfluenceType.Mobility:
return(GetPawnMobility(startingCoordinate, board, pieceColor));
default:
throw new NotImplementedException();
}
}
internal static IEnumerable <SquareCoordinate> GetAllInBetweenSquares(this SquareCoordinate startingCoordinate, SquareCoordinate endingCoordinate)
{
var ret = new List <SquareCoordinate>();
if (startingCoordinate.IsOnDiagonal(endingCoordinate))
{
Extensions.AddRange(ret, GetDiagonalInBetweenPositions(startingCoordinate, endingCoordinate));
}
if (startingCoordinate.IsOnRankOrFile(endingCoordinate))
{
Extensions.AddRange(ret, GetStraightInBetweenPosition(startingCoordinate, endingCoordinate));
}
return(ret);
}
private static bool DoubleForwardMoveAllowed(Board board, Color color, SquareCoordinate square, out SquareCoordinate?allowedSquare)
{
var singleRankMove = square.Rank + color.MovingDirection;
var doubleRankMove = square.Rank + color.MovingDirection * 2;
var isAllowed = square.Rank == color.PawnFirstRank &&
!board.IsAnyPieceInSquare(singleRankMove, square.File) &&
!board.IsAnyPieceInSquare(doubleRankMove, square.File);
allowedSquare = isAllowed
? new SquareCoordinate(doubleRankMove, square.File)
: (SquareCoordinate?)null;
return(isAllowed);
}
internal static IEnumerable <SquareCoordinate> GetLineAvailability(SquareCoordinate startingCoordinate, Board board, Color pieceColor, SquareInfluenceType availabilityType)
{
var ret = new List <SquareCoordinate>();
//Upper line
for (int i = 1; i < 8; i++)
{
var rank = startingCoordinate.Rank + i;
var file = startingCoordinate.File;
if (TryAddPieceGetIsLast(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType))
{
break;
}
}
//Bottom line
for (int i = 1; i < 8; i++)
{
var rank = startingCoordinate.Rank - i;
var file = startingCoordinate.File;
if (TryAddPieceGetIsLast(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType))
{
break;
}
}
//Right line
for (int i = 1; i < 8; i++)
{
var rank = startingCoordinate.Rank;
var file = startingCoordinate.File + i;
if (TryAddPieceGetIsLast(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType))
{
break;
}
}
//Left line
for (int i = 1; i < 8; i++)
{
var rank = startingCoordinate.Rank;
var file = startingCoordinate.File - i;
if (TryAddPieceGetIsLast(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType))
{
break;
}
}
return(ret);
}
private static bool TryAddPieceGetIsLast(List <SquareCoordinate> ret,
SquareCoordinate startingSquare,
int newRank,
int newFile,
Board board,
Color pieceColor,
SquareInfluenceType availabilityType)
{
if (!IsValidPosition(newRank, newFile))
{
return(true);
}
TryAddSquare(ret, startingSquare, newRank, newFile, board, pieceColor, availabilityType);
return(board.IsAnyPieceInSquare(new SquareCoordinate(newRank, newFile)));
}
private static IEnumerable <SquareCoordinate> GetDiagonalInBetweenPositions(SquareCoordinate startingCoordinate, SquareCoordinate endingCoordinate)
{
var ret = new List <SquareCoordinate>();
var shift = Math.Abs(endingCoordinate.Rank - startingCoordinate.Rank);
var fileDirection = Math.Sign(endingCoordinate.File - startingCoordinate.File);
var rankDirection = Math.Sign(endingCoordinate.Rank - startingCoordinate.Rank);
for (int i = 1; i < shift; i++)
{
var rank = startingCoordinate.Rank + (rankDirection * i);
var file = startingCoordinate.File + (fileDirection * i);
ret.Add(new SquareCoordinate(rank, file));
}
return(ret);
}
internal static IEnumerable <SquareCoordinate> GetKnightAvailability(SquareCoordinate startingCoordinate, Board board, Color pieceColor, SquareInfluenceType availabilityType)
{
var ret = new List <SquareCoordinate>();
//Upper right, up
var rank = startingCoordinate.Rank + 2;
var file = startingCoordinate.File + 1;
TryAddSquare(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType);
//Upper right, right
rank = startingCoordinate.Rank + 1;
file = startingCoordinate.File + 2;
TryAddSquare(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType);
//Upper left, up
rank = startingCoordinate.Rank + 2;
file = startingCoordinate.File - 1;
TryAddSquare(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType);
//Upper left, right
rank = startingCoordinate.Rank + 1;
file = startingCoordinate.File - 2;
TryAddSquare(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType);
//Bottom right, bottom
rank = startingCoordinate.Rank - 2;
file = startingCoordinate.File + 1;
TryAddSquare(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType);
//Bottom right, right
rank = startingCoordinate.Rank - 1;
file = startingCoordinate.File + 2;
TryAddSquare(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType);
//Bottom left, bottom
rank = startingCoordinate.Rank - 2;
file = startingCoordinate.File - 1;
TryAddSquare(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType);
//Bottom left, right
rank = startingCoordinate.Rank - 1;
file = startingCoordinate.File - 2;
TryAddSquare(ret, startingCoordinate, rank, file, board, pieceColor, availabilityType);
return(ret);
}
private static IEnumerable <SquareCoordinate> GetPawnControl(SquareCoordinate startingCoordinate, Board board, Color color)
{
var ret = new List <SquareCoordinate>();
var captureRank = startingCoordinate.Rank + color.MovingDirection;
var leftCaptureFile = startingCoordinate.File - 1;
var rightCaptureFile = startingCoordinate.File + 1;
if (IsValidPosition(captureRank, leftCaptureFile))
{
ret.Add(new SquareCoordinate(captureRank, leftCaptureFile));
}
if (IsValidPosition(captureRank, rightCaptureFile))
{
ret.Add(new SquareCoordinate(captureRank, rightCaptureFile));
}
return(ret);
}
internal static IEnumerable <SquareCoordinate> GetPawnFrontSquares(SquareCoordinate square, Color color)
{
var ret = new List <SquareCoordinate>();
//Left
if (IsValidPosition(square.Rank + color.MovingDirection, square.File - 1))
{
ret.Add(new SquareCoordinate(square.Rank + color.MovingDirection, square.File - 1));
}
//In front
if (IsValidPosition(square.Rank + color.MovingDirection, square.File))
{
ret.Add(new SquareCoordinate(square.Rank + color.MovingDirection, square.File));
}
//Right
if (IsValidPosition(square.Rank + color.MovingDirection, square.File + 1))
{
ret.Add(new SquareCoordinate(square.Rank + color.MovingDirection, square.File + 1));
}
return(ret);
}
internal bool IsControlledByColor(SquareCoordinate coordinate, Color color)
{
return(_piecesInfluenceManager.IsControlledByColor(this[coordinate], color));
}
public Square this[SquareCoordinate coordinate]
{
get { return(_position[coordinate]); }
}
internal bool IsAnyOpponentPieceInSquare(SquareCoordinate coordinate, Color color)
{
return(_position[coordinate].ContainsOpponentPiece(color));
}
internal bool IsAnyPieceInSquare(SquareCoordinate coordinate)
{
return(_position[coordinate].ContainsPiece());
}
internal bool CanPieceOfColorGoToSquare(SquareCoordinate coordinate, Color color)
{
return(_position[coordinate].Piece == null ||
_position[coordinate].Piece.Color.IsOpponentColor(color));
}
private Square CreateSquare(SquareCoordinate coordinate)
{
return(new Square(coordinate));
}
private KeyValuePair <SquareCoordinate, Square> CreateSquare(int rank, int file)
{
var coordinate = new SquareCoordinate(rank, file);
return(new KeyValuePair <SquareCoordinate, Square>(coordinate, CreateSquare(coordinate)));
}
internal static int GetFileDifference(this SquareCoordinate startingCoordinate, SquareCoordinate endingCoordinate)
{
return(endingCoordinate.File - startingCoordinate.File);
}