/// <summary>
/// Apply a FEN string board setup to the board structure.
/// *EXCEPTION FREE FUNCTION*
/// </summary>
/// <param name="fenString">The string to set</param>
/// <param name="validate">If true, the fen string is validated, otherwise not</param>
/// <returns>
/// 0 = all ok.
/// -1 = Error in piece file layout parsing
/// -2 = Error in piece rank layout parsing
/// -3 = Unknown piece detected
/// -4 = Error while parsing moving side
/// -5 = Error while parsing castleling
/// -6 = Error while parsing en-passant square
/// -9 = FEN length exceeding maximum
/// </returns>
public FenError SetFen(string fenString, bool validate = false)
{
// TODO : Replace with stream at some point
// basic validation, catches format errors
if (validate)
{
Fen.Fen.Validate(fenString);
}
foreach (var square in Occupied)
{
Position.RemovePiece(square, Position.BoardLayout[square.AsInt()]);
}
//for (var i = 0; i <= PositionIndex; i++)
// _stateList[i].Clear();
Position.Clear();
var fen = new FenData(fenString);
Player player;
var c = fen.GetAdvance;
var f = 1; // file (column)
var r = 8; // rank (row)
// map pieces to data structure
while (c != 0 && !(f == 9 && r == 1))
{
if (char.IsDigit(c))
{
f += c - '0';
if (f > 9)
{
return(new FenError(-1, fen.Index));
}
c = fen.GetAdvance;
continue;
}
if (c == '/')
{
if (f != 9)
{
return(new FenError(-2, fen.Index));
}
r--;
f = 1;
c = fen.GetAdvance;
continue;
}
var pieceIndex = PieceExtensions.PieceChars.IndexOf(c);
if (pieceIndex == -1)
{
return(new FenError(-3, fen.Index));
}
player = char.IsLower(PieceExtensions.PieceChars[pieceIndex]);
var square = new Square(r - 1, f - 1);
AddPiece(square, player, (EPieceType)pieceIndex);
c = fen.GetAdvance;
f++;
}
if (!Fen.Fen.IsDelimiter(c))
{
return(new FenError(-4, fen.Index));
}
c = fen.GetAdvance;
player = c == 'w' ? 0 : 1;
if (player == -1)
{
return(new FenError(-4, fen.Index));
}
if (!Fen.Fen.IsDelimiter(fen.GetAdvance))
{
return(new FenError(-5, fen.Index));
}
if (!SetupCastleling(fen))
{
return(new FenError(-5, fen.Index));
}
if (!Fen.Fen.IsDelimiter(fen.GetAdvance))
{
return(new FenError(-6, fen.Index));
}
State.EnPassantSquare = fen.GetEpSquare();
// temporary.. the whole method should be using this, but this will do for now.
var moveCounters = fen.Fen.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
var first = moveCounters[moveCounters.Length - 2];
var second = moveCounters[moveCounters.Length - 1];
second.ToIntegral(out int number);
if (number > 0)
{
number -= 1;
}
PositionIndex = PositionStart = number;
first.ToIntegral(out number);
State = Position.State = _stateList[PositionIndex];
State.ReversibleHalfMoveCount = number;
State.SideToMove = player;
if (player.IsBlack())
{
var zobristSide = Zobrist.GetZobristSide();
State.Key ^= zobristSide;
State.PawnStructureKey ^= zobristSide;
}
State.Key ^= Zobrist.GetZobristCastleling(State.CastlelingRights);
if (State.EnPassantSquare != ESquare.none)
{
State.Key ^= Zobrist.GetZobristEnPessant(State.EnPassantSquare.File().AsInt());
}
Position.InCheck = Position.IsAttacked(Position.GetPieceSquare(EPieceType.King, State.SideToMove), ~State.SideToMove);
//State.GenerateMoves(true);
return(0);
}
/// <summary>
/// Updates the hash key depending on a move
/// </summary>
/// <param name="move">The move the hash key is depending on</param>
private void UpdateKey(Move move)
{
// TODO : Merge with MakeMove to avoid duplicate ifs
var pawnKey = State.PawnStructureKey;
var key = State.Key ^ pawnKey;
pawnKey ^= Zobrist.GetZobristSide();
if (_stateList[PositionIndex - 1].EnPassantSquare != ESquare.none)
{
key ^= Zobrist.GetZobristEnPessant(_stateList[PositionIndex - 1].EnPassantSquare.File().AsInt());
}
if (State.EnPassantSquare != ESquare.none)
{
key ^= Zobrist.GetZobristEnPessant(State.EnPassantSquare.File().AsInt());
}
if (move.IsNullMove())
{
key ^= pawnKey;
State.Key = key;
State.PawnStructureKey = pawnKey;
return;
}
var pawnPiece = move.GetMovingPieceType() == EPieceType.Pawn;
if (pawnPiece)
{
pawnKey ^= Zobrist.GetZobristPst(move.GetMovingPiece(), move.GetFromSquare());
}
else
{
key ^= Zobrist.GetZobristPst(move.GetMovingPiece(), move.GetFromSquare());
}
var squareTo = move.GetToSquare();
if (move.IsPromotionMove())
{
key ^= Zobrist.GetZobristPst(move.GetPromotedPiece(), squareTo);
}
else
{
if (pawnPiece)
{
pawnKey ^= Zobrist.GetZobristPst(move.GetMovingPiece(), squareTo);
}
else
{
key ^= Zobrist.GetZobristPst(move.GetMovingPiece(), squareTo);
}
}
if (pawnPiece && move.IsEnPassantMove())
{
pawnKey ^= Zobrist.GetZobristPst(move.GetCapturedPiece().Type() + (State.SideToMove << 3), squareTo + (State.SideToMove.Side == 0 ? 8 : -8));
}
else if (move.IsCaptureMove())
{
if (pawnPiece)
{
pawnKey ^= Zobrist.GetZobristPst(move.GetCapturedPiece(), squareTo);
}
else
{
key ^= Zobrist.GetZobristPst(move.GetCapturedPiece(), squareTo);
}
}
else if (move.IsCastlelingMove())
{
var piece = (EPieces)(EPieceType.Rook + move.GetSideMask());
key ^= Zobrist.GetZobristPst(piece, Position.GetRookCastleFrom(squareTo));
key ^= Zobrist.GetZobristPst(piece, squareTo.GetRookCastleTo());
}
// castleling
// castling rights
if (State.CastlelingRights != _stateList[PositionIndex - 1].CastlelingRights)
{
key ^= Zobrist.GetZobristCastleling(_stateList[PositionIndex - 1].CastlelingRights);
key ^= Zobrist.GetZobristCastleling(State.CastlelingRights);
}
key ^= pawnKey;
State.Key = key;
State.PawnStructureKey = pawnKey;
}
public void Hash(ECastleling castleling, ERank rank) => Value ^= Zobrist.GetZobristCastleling((int)rank);
