99 lines
3.1 KiB
Scala
99 lines
3.1 KiB
Scala
package gambit
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object Fen:
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val startPosition = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
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def parse(fen: String): Position =
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val parts = fen.trim.split("\\s+")
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val pos = new Position
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var rank = 7
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for row <- parts(0).split("/") do
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var file = 0
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for ch <- row do
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if ch.isDigit then file += (ch - '0')
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else
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val piece = charToPiece(ch)
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val sq = Square.make(file, rank)
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pos.board(sq) = piece
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if (piece & 7) == Piece.King then pos.kingSquare(piece >> 3) = sq
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file += 1
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rank -= 1
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pos.sideToMove = if parts(1) == "w" then Color.White else Color.Black
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var castle = 0
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if parts(2) != "-" then
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for ch <- parts(2) do
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ch match
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case 'K' => castle |= Castling.WhiteKing
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case 'Q' => castle |= Castling.WhiteQueen
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case 'k' => castle |= Castling.BlackKing
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case 'q' => castle |= Castling.BlackQueen
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case _ => ()
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pos.castling = castle
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pos.epSquare = if parts(3) == "-" then -1 else Square.fromName(parts(3))
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pos.halfmove = if parts.length > 4 then parts(4).toInt else 0
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pos.fullmove = if parts.length > 5 then parts(5).toInt else 1
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pos.hash = pos.computeHash()
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pos
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def toFen(pos: Position): String =
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val sb = new StringBuilder
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var rank = 7
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while rank >= 0 do
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var empty = 0
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var file = 0
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while file < 8 do
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val p = pos.board(Square.make(file, rank))
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if p == Piece.Empty then empty += 1
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else
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if empty > 0 then
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sb.append(empty)
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empty = 0
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sb.append(pieceToChar(p))
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file += 1
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if empty > 0 then sb.append(empty)
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if rank > 0 then sb.append('/')
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rank -= 1
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sb.append(' ')
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sb.append(if pos.sideToMove == Color.White then 'w' else 'b')
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sb.append(' ')
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if pos.castling == 0 then sb.append('-')
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else
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if (pos.castling & Castling.WhiteKing) != 0 then sb.append('K')
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if (pos.castling & Castling.WhiteQueen) != 0 then sb.append('Q')
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if (pos.castling & Castling.BlackKing) != 0 then sb.append('k')
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if (pos.castling & Castling.BlackQueen) != 0 then sb.append('q')
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sb.append(' ')
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sb.append(if pos.epSquare < 0 then "-" else Square.name(pos.epSquare))
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sb.append(' ')
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sb.append(pos.halfmove)
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sb.append(' ')
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sb.append(pos.fullmove)
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sb.toString
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private def charToPiece(ch: Char): Int =
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val color = if ch.isUpper then Color.White else Color.Black
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val pieceType = ch.toLower match
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case 'p' => Piece.Pawn
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case 'n' => Piece.Knight
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case 'b' => Piece.Bishop
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case 'r' => Piece.Rook
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case 'q' => Piece.Queen
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case 'k' => Piece.King
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case _ => Piece.Empty
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Piece.make(color, pieceType)
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private def pieceToChar(piece: Int): Char =
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val letter = Piece.typeOf(piece) match
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case Piece.Pawn => 'p'
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case Piece.Knight => 'n'
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case Piece.Bishop => 'b'
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case Piece.Rook => 'r'
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case Piece.Queen => 'q'
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case Piece.King => 'k'
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case _ => '?'
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if Piece.colorOf(piece) == Color.White then letter.toUpper else letter
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