Fix bugs with en passant
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54a6217bd3
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@ -133,12 +133,15 @@ proc doMove(self: ChessBoard, move: Move)
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proc pretty*(self: ChessBoard): string
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proc spawnPiece(self: ChessBoard, location: Location, piece: Piece)
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proc updateAttackedSquares(self: ChessBoard)
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proc updateSlidingAttacks(self: ChessBoard)
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proc getPinnedDirections(self: ChessBoard, loc: Location): seq[Location]
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proc getAttacks*(self: ChessBoard, loc: Location): Attacked
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proc getSlidingAttacks(self: ChessBoard, loc: Location): tuple[attacks: Attacked, pins: Attacked]
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proc inCheck*(self: ChessBoard, color: PieceColor = None): bool
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proc toFEN*(self: ChessBoard): string
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proc undoLastMove*(self: ChessBoard)
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proc movePiece(self: ChessBoard, move: Move, attack: bool = true)
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proc removePiece(self: ChessBoard, location: Location, attack: bool = true)
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proc extend[T](self: var seq[T], other: openarray[T]) {.inline.} =
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@ -847,27 +850,21 @@ proc generatePawnMoves(self: ChessBoard, location: Location): seq[Move] =
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if target.isValid():
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let otherPiece = self.grid[target]
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if target == self.position.enPassantSquare and self.grid[enPassantPawn].color == piece.color.opposite():
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# Ensure en passant doesn't create a check
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let king = self.getKing(piece.color)
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var ok = true
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if king.row == location.row:
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var current = location
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while true:
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current = current + piece.color.rightSide()
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if not current.isValid():
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break
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let p = self.grid[current.row, current.col]
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if p.color == piece.color:
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break
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if p.color == None:
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continue
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# Bishops can't create checks through en passant (neither can knights)
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if p.color == piece.color.opposite() and p.kind in [Queen, Rook]:
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ok = false
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break
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if ok:
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# En passant may be possible
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let targetPawn = self.grid[enPassantPawn]
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# Remove both pieces and see if the king ends up in check
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self.removePiece(enPassantPawn, attack=false)
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self.removePiece(location, attack=false)
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self.updateAttackedSquares()
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if not self.inCheck(piece.color):
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# King is not in check after en passant: move is legal
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directions.add(diagonal)
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# Reset what we just did and reupdate the attack metadata
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self.spawnPiece(location, piece)
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self.spawnPiece(enPassantPawn, targetPawn)
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self.updateAttackedSquares()
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elif otherPiece.color == piece.color.opposite() and otherPiece.kind != King: # Can't capture the king!
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# A capture may be possible
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directions.add(diagonal)
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# Check for pins
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let pinned = self.getPinnedDirections(location)
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@ -924,8 +921,9 @@ proc generateSlidingMoves(self: ChessBoard, location: Location): seq[Move] =
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if direction in pinned:
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newDirections.add(direction)
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directions = newDirections
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let checked = self.inCheck()
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let resolutions = if not checked: @[] else: self.getCheckResolutions(piece.color)
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let
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checked = self.inCheck()
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resolutions = if not checked: @[] else: self.getCheckResolutions(piece.color)
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for direction in directions:
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# Slide in this direction as long as it's possible
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var
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@ -1333,9 +1331,10 @@ proc updateSlidingAttacks(self: ChessBoard) =
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proc updateAttackedSquares(self: ChessBoard) =
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## Updates internal metadata about which squares
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## are attacked
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self.position.attacked.white.setLen(0)
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self.position.attacked.black.setLen(0)
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self.position.pinned.white.setLen(0)
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self.position.pinned.black.setLen(0)
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# Pawns
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self.updatePawnAttacks()
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# Sliding pieces
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@ -1687,8 +1686,6 @@ proc undoLastMove*(self: ChessBoard) =
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proc isLegal(self: ChessBoard, move: Move): bool {.inline.} =
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## Returns whether the given move is legal
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if self.grid[move.startSquare.row, move.startSquare.col].color != self.getActiveColor():
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return false
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return move in self.generateMoves(move.startSquare)
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@ -2047,6 +2044,8 @@ proc handleMoveCommand(board: ChessBoard, command: seq[string]): Move {.discarda
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move.flags = move.flags or CastleLong.uint16
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elif move.targetSquare == move.startSquare + shortCastleKing():
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move.flags = move.flags or CastleShort.uint16
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if move.targetSquare == board.getEnPassantTarget():
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move.flags = move.flags or EnPassant.uint16
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result = board.makeMove(move)
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if result == emptyMove():
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echo &"Error: move: {moveString} is illegal"
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@ -2095,7 +2094,7 @@ proc handlePositionCommand(board: var ChessBoard, command: seq[string]) =
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try:
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tempBoard = newChessboardFromFEN(fenString)
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except ValueError:
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echo &"Error: position: {getCurrentExceptionMsg()}"
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echo &"error: position: {getCurrentExceptionMsg()}"
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return
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if args.len() > 0:
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var i = 0
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@ -2113,6 +2112,9 @@ proc handlePositionCommand(board: var ChessBoard, command: seq[string]) =
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echo board
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of "pretty":
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echo board.pretty()
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else:
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echo &"error: position: unknown subcommand '{command[1]}'"
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return
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proc handleUCICommand(board: var ChessBoard, command: seq[string]) =
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@ -2154,7 +2156,8 @@ const HELP_TEXT = """Nimfish help menu:
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- ep: Print the current en passant target
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- pretty: Shorthand for "position pretty"
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- print: Shorthand for "position print"
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- fen: Shorthand for "position fen" (print only!)
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- fen: Shorthand for "position fen"
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- pos <args>: Shorthand for "position <args>"
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- get <square>: Get the piece on the given square
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- uci: enter UCI mode (WIP)
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"""
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@ -2189,7 +2192,7 @@ proc main: int =
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echo HELP_TEXT
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of "go":
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handleGoCommand(board, cmd)
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of "position":
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of "position", "pos":
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handlePositionCommand(board, cmd)
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of "move":
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handleMoveCommand(board, cmd)
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