/*
* Remove castling flags that arent valid
*/
private static void removeInvalidCastleFlags(Position position)
{
int castleMask = position.getCastleMask();
int validCastle = 0;
if (position.getPiece(4) == PieceType.K)
{
if (position.getPiece(0) == PieceType.R) validCastle |= (1 << Position.A1_CASTLE);
if (position.getPiece(7) == PieceType.R) validCastle |= (1 << Position.H1_CASTLE);
}
if (position.getPiece(60) == PieceType.k)
{
if (position.getPiece(56) == PieceType.r) validCastle |= (1 << Position.A8_CASTLE);
if (position.getPiece(63) == PieceType.r) validCastle |= (1 << Position.H8_CASTLE);
}
castleMask &= validCastle;
position.setCastleMask(castleMask);
}
/*
* Parse a FEN string and return a position object
*/
public static Position convertFENToPosition(String fen)
{
Position position = new Position();
String[] terms = fen.Split(' ');
if (terms.Length < 2)
{
System.Console.WriteLine("Too few terms");
}
for (int i = 0; i < terms.Length; i++)
{
terms[i] = terms[i].Trim();
}
//Piece placement
int rank = 7;
int file = 0;
for (int i = 0; i < terms[0].Length; i++)
{
char c = (char)terms[0].ToCharArray().GetValue(i);
switch (c)
{
case '1': file += 1; break;
case '2': file += 2; break;
case '3': file += 3; break;
case '4': file += 4; break;
case '5': file += 5; break;
case '6': file += 6; break;
case '7': file += 7; break;
case '8': file += 8; break;
case '/': rank--; file = 0; break;
case 'P': setPieceSafely(position, file, rank, PieceType.P); file++; break;
case 'N': setPieceSafely(position, file, rank, PieceType.N); file++; break;
case 'B': setPieceSafely(position, file, rank, PieceType.B); file++; break;
case 'R': setPieceSafely(position, file, rank, PieceType.R); file++; break;
case 'Q': setPieceSafely(position, file, rank, PieceType.Q); file++; break;
case 'K': setPieceSafely(position, file, rank, PieceType.K); file++; break;
case 'p': setPieceSafely(position, file, rank, PieceType.p); file++; break;
case 'n': setPieceSafely(position, file, rank, PieceType.n); file++; break;
case 'b': setPieceSafely(position, file, rank, PieceType.b); file++; break;
case 'r': setPieceSafely(position, file, rank, PieceType.r); file++; break;
case 'q': setPieceSafely(position, file, rank, PieceType.q); file++; break;
case 'k': setPieceSafely(position, file, rank, PieceType.k); file++; break;
default: throw new ParserError("Invalid Piece", position);
}
}
//Active Colour
if (terms[1].Length > 0)
{
Boolean whiteToMove;
char c = (char)terms[1].ToCharArray().GetValue(0);
switch (c)
{
case 'w': whiteToMove = true; break;
case 'b': whiteToMove = false; break;
default: throw new ParserError("Invalid Active Colour", position);
}
position.setWhiteMove(whiteToMove);
}
else
{
throw new ParserError("Invalid Active Colour", position);
}
//Castling Rights
int castleMask = 0;
if (terms.Length > 2)
{
for (int i = 0; i < terms[2].Length; i++)
{
char c = (char)terms[2].ToCharArray().GetValue(i);
switch (c)
{
case 'K':
castleMask |= (1 << Position.H1_CASTLE);
break;
case 'Q':
castleMask |= (1 << Position.A1_CASTLE);
break;
case 'k':
castleMask |= (1 << Position.H8_CASTLE);
break;
case 'q':
castleMask |= (1 << Position.A8_CASTLE);
break;
case '-':
break;
default:
throw new ParserError("Invalid castling flags", position);
}
}
}
position.setCastleMask(castleMask);
removeInvalidCastleFlags(position);
//En Passant Target Square
if (terms.Length > 3)
{
String epString = terms[3];
if (!epString.Equals("-"))
{
if (epString.Length < 2)
{
throw new ParserError("Invalid En Passent Square", position);
}
position.setEpSquare(getSquare(epString));
}
}
try
{
//Halfmove Clock
if (terms.Length > 4)
{
position.halfMoveClock = Convert.ToInt32(terms[4]);
}
//Full Move Counter
if (terms.Length > 5)
{
position.fullMoveCounter = Convert.ToInt32(terms[5]);
}
}
catch (ArgumentException ae)
{
//Ignore errors here since fields are optional
}
//Each side must have exactly one king
int maxNumber = (int)PieceType.Empty + 1;
int[] numPieces = new int[maxNumber];
for (int i = 0; i < maxNumber; i++)
{
numPieces[i] = 0;
}
for (file = 0; file < 8; file++)
{
for (rank = 0; rank < 8; rank++)
{
numPieces[(int)position.getPiece(Position.getSquare(file, rank))]++;
}
}
if (numPieces[(int)PieceType.K] != 1)
{
throw new ParserError("Too many white kings", position);
}
if (numPieces[(int)PieceType.k] != 1)
{
throw new ParserError("Too many black kings", position);
}
//White must not have too many pieces
int maxWPawns = 8;
maxWPawns -= Math.Max(0, numPieces[(int)PieceType.N] - 2);
maxWPawns -= Math.Max(0, numPieces[(int)PieceType.B] - 2);
maxWPawns -= Math.Max(0, numPieces[(int)PieceType.R] - 2);
maxWPawns -= Math.Max(0, numPieces[(int)PieceType.Q] - 1);
if (numPieces[(int)PieceType.P] > maxWPawns)
{
throw new ParserError("Too many white pieces", position);
}
//Black must not have too many pieces
int maxBPawns = 8;
maxBPawns -= Math.Max(0, numPieces[(int)PieceType.n] - 2);
maxBPawns -= Math.Max(0, numPieces[(int)PieceType.b] - 2);
maxBPawns -= Math.Max(0, numPieces[(int)PieceType.r] - 2);
maxBPawns -= Math.Max(0, numPieces[(int)PieceType.q] - 1);
//Make sure king can not be captured
Position pos2 = new Position(position);
pos2.setWhiteMove(!position.whiteMove);
if (MoveGenerator.inCheck(pos2))
{
throw new ParserError("King capture possible", position);
}
fixupEPSquare(position);
return position;
}
/*
* Convert a piece placement string to a position object
* This does not have to adhere to the strict rules of how
* many pieces a player must have. i.e.(player may have no king)
* This is primarily used for testing purposes, as well as tutorial
* scenarios.
*/
public static Position convertPiecePlacementToPosition(String fen)
{
Position position = new Position();
String[] terms = fen.Split(' ');
if (terms.Length < 2)
{
System.Console.WriteLine("Too few terms");
}
for (int i = 0; i < terms.Length; i++)
{
terms[i] = terms[i].Trim();
}
//Piece placement
int rank = 7;
int file = 0;
for (int i = 0; i < terms[0].Length; i++)
{
char c = (char)terms[0].ToCharArray().GetValue(i);
switch (c)
{
case '1': file += 1; break;
case '2': file += 2; break;
case '3': file += 3; break;
case '4': file += 4; break;
case '5': file += 5; break;
case '6': file += 6; break;
case '7': file += 7; break;
case '8': file += 8; break;
case '/': rank--; file = 0; break;
case 'P': position.setPiece(Position.getSquare(file, rank), PieceType.P); file++; break;
case 'N': position.setPiece(Position.getSquare(file, rank), PieceType.N); file++; break;
case 'B': position.setPiece(Position.getSquare(file, rank), PieceType.B); file++; break;
case 'R': position.setPiece(Position.getSquare(file, rank), PieceType.R); file++; break;
case 'Q': position.setPiece(Position.getSquare(file, rank), PieceType.Q); file++; break;
case 'K': position.setPiece(Position.getSquare(file, rank), PieceType.K); file++; break;
case 'p': position.setPiece(Position.getSquare(file, rank), PieceType.p); file++; break;
case 'n': position.setPiece(Position.getSquare(file, rank), PieceType.n); file++; break;
case 'b': position.setPiece(Position.getSquare(file, rank), PieceType.b); file++; break;
case 'r': position.setPiece(Position.getSquare(file, rank), PieceType.r); file++; break;
case 'q': position.setPiece(Position.getSquare(file, rank), PieceType.q); file++; break;
case 'k': position.setPiece(Position.getSquare(file, rank), PieceType.k); file++; break;
default: throw new ParserError("Invalid Piece", position);
}
}
//Active Colour
if (terms[1].Length > 0)
{
Boolean whiteToMove;
char c = (char)terms[1].ToCharArray().GetValue(0);
switch (c)
{
case 'w': whiteToMove = true; break;
case 'b': whiteToMove = false; break;
default: throw new ParserError("Invalid Active Colour", position);
}
position.setWhiteMove(whiteToMove);
}
else
{
throw new ParserError("Invalid Active Colour", position);
}
//Castling Rights
int castleMask = 0;
if (terms.Length > 2)
{
for (int i = 0; i < terms[2].Length; i++)
{
char c = (char)terms[2].ToCharArray().GetValue(i);
switch (c)
{
case 'K':
castleMask |= (1 << Position.H1_CASTLE);
break;
case 'Q':
castleMask |= (1 << Position.A1_CASTLE);
break;
case 'k':
castleMask |= (1 << Position.H8_CASTLE);
break;
case 'q':
castleMask |= (1 << Position.A8_CASTLE);
break;
case '-':
break;
default:
throw new ParserError("Invalid castling flags", position);
}
}
}
position.setCastleMask(castleMask);
removeInvalidCastleFlags(position);
//En Passant Target Square
if (terms.Length > 3)
{
String epString = terms[3];
if (!epString.Equals("-"))
{
if (epString.Length < 2)
{
throw new ParserError("Invalid En Passent Square", position);
}
position.setEpSquare(getSquare(epString));
}
}
try
{
//Halfmove Clock
if (terms.Length > 4)
{
position.halfMoveClock = Convert.ToInt32(terms[4]);
}
//Full Move Counter
if (terms.Length > 5)
{
position.fullMoveCounter = Convert.ToInt32(terms[5]);
}
}
catch (ArgumentException ae)
{
//Ignore errors here since fields are optional
Console.WriteLine(ae.ToString());
}
fixupEPSquare(position);
return position;
}