diff --git a/src/chess.nim b/src/chess.nim index 20d8d92..fb7fca5 100644 --- a/src/chess.nim +++ b/src/chess.nim @@ -109,8 +109,7 @@ const (0, 1, 0, 0, 0), # bishop only (0, 2, 0, 0, 0) # 2 knights ] ## `InsufficientMaterial` describes the pieces where no checkmate can be - ## forced. - + ## forced let PieceChar = { @@ -144,47 +143,65 @@ let # `FileChar` maps the files of the chessboard to numbers for better # conversion. -proc checkInsufficientMaterial(board: Board): bool = - ## Checks for combinations of pieces on a `board`, where no checkmate can be - ## forced. - ## Returns true if no player can force a checkmate to the other. - var wp = 0 - var wn = 0 - var wb = 0 - var wr = 0 - var wq = 0 - var bp = 0 - var bn = 0 - var bb = 0 - var br = 0 - var bq = 0 - for field in board.low..board.high: - case board[field]: - of WPawn: - wp = wp + 1 - of BPawn: - bp = bp + 1 - of WKnight: - wn = wn + 1 - of BKnight: - bn = bn + 1 - of WBishop: - wb = wb + 1 - of BBishop: - bb = bb + 1 - of WRook: - wr = wr + 1 - of BRook: - br = br + 1 - of WQueen: - wq = wq + 1 - of BQueen: - bq = bq + 1 - else: - continue - let wpieces: PieceAmount = (wp, wn, wb, wr, wq) - let bpieces: PieceAmount = (bp, bn, bb, br, bq) - return (wpieces in InsufficientMaterial) and (bpieces in InsufficientMaterial) +proc fieldToInd*(file: string, line: int): int = + ## Calculate and return board index from `file` and `line` of a chess board. + ## Returns -1 if the `field` was not input correct. + try: + return 1+(line+1)*10+FileChar[file] + except IndexDefect, ValueError: + return -1 + +proc fieldToInd*(field: string): int = + ## Calculate and return board index from `field` of a chess board. + ## Returns -1 if the `field` was not input correct. + try: + return fieldToInd($field[0], parseInt($field[1])) + except IndexDefect, ValueError: + return -1 + +proc indToField*(ind: int): string = + ## Calculate and returns field name from board index `ind`. + let line = (int)ind/10-1 + let file_ind = (ind)%%10-1 + for file, i in FileChar: + if FileChar[file] == file_ind: + return $file & $line + +proc getMove*(start: int, dest: int, prom: int, color: Color): Move = + ## Get a move object of the `color` player from `start` to `dest` with an + ## eventual promition to `prom`. + var move = Move(start: start, dest: dest, prom: prom * ord(color), color: color) + if (WKnight > prom or WQueen < prom): + move.prom = WQueen + return move + +proc getMove*(start: int, dest: int, color: Color): Move = + ## Get a move object of the `color` player from `start` to `dest` with + ## automatic promition to queen. + var move = Move(start: start, dest: dest, prom: WQueen * ord(color), color: color) + return move + +proc notationToMove*(notation: string, color: Color): Move = + ## Convert and return simplified algebraic chess `notation` to a move object, + ## color of player is `color`. + var move: Move + var start = fieldToInd(notation[0..1]) + var dest = fieldToInd(notation[2..3]) + move = getMove(start, dest, color) + if (len(notation) > 4): + var promStr = $notation[4] + var prom: int + case promStr: + of "Q": + prom = WQueen * ord(color) + of "R": + prom = WRook * ord(color) + of "B": + prom = WBishop * ord(color) + of "N": + prom = WKnight * ord(color) + move = getMove(start, dest, prom, color) + return move proc initBoard(): Board = ## Create and return a board with pieces in starting position. @@ -256,20 +273,6 @@ proc initGame*(board: array[0..63, int], color: Color): Game = fiftyMoveCounter: 0) return game -proc getMove*(start: int, dest: int, prom: int, color: Color): Move = - ## Get a move object of the `color` player from `start` to `dest` with an - ## eventual promition to `prom`. - var move = Move(start: start, dest: dest, prom: prom * ord(color), color: color) - if (WKnight > prom or WQueen < prom): - move.prom = WQueen - return move - -proc getMove*(start: int, dest: int, color: Color): Move = - ## Get a move object of the `color` player from `start` to `dest` with - ## automatic promition to queen. - var move = Move(start: start, dest: dest, prom: WQueen * ord(color), color: color) - return move - proc echoBoard*(game: Game, color: Color) = ## Prints out the given `board` with its pieces as characters and line ## indices from perspecive of `color`. @@ -293,30 +296,6 @@ proc echoBoard*(game: Game, color: Color) = echo line_str echo "a b c d e f g h" -proc fieldToInd*(file: string, line: int): int = - ## Calculate and return board index from `file` and `line` of a chess board. - ## Returns -1 if the `field` was not input correct. - try: - return 1+(line+1)*10+FileChar[file] - except IndexDefect, ValueError: - return -1 - -proc fieldToInd*(field: string): int = - ## Calculate and return board index from `field` of a chess board. - ## Returns -1 if the `field` was not input correct. - try: - return fieldToInd($field[0], parseInt($field[1])) - except IndexDefect, ValueError: - return -1 - -proc indToField*(ind: int): string = - ## Calculate and returns field name from board index `ind`. - let line = (int)ind/10-1 - let file_ind = (ind)%%10-1 - for file, i in FileChar: - if FileChar[file] == file_ind: - return $file & $line - proc genCastleRights(moved: Moved): CastleRights = ## Generate and return rights to castle from given `moved` let wk = not moved[fieldToInd("e1")] and not moved[fieldToInd("h1")] @@ -325,27 +304,84 @@ proc genCastleRights(moved: Moved): CastleRights = let bq = not moved[fieldToInd("e8")] and not moved[fieldToInd("a8")] return (wk, wq, bk, bq) -proc notationToMove*(notation: string, color: Color): Move = - ## Convert and return simplified algebraic chess `notation` to a move object, - ## color of player is `color`. - var move: Move - var start = fieldToInd(notation[0..1]) - var dest = fieldToInd(notation[2..3]) - move = getMove(start, dest, color) - if (len(notation) > 4): - var promStr = $notation[4] - var prom: int - case promStr: - of "Q": - prom = WQueen * ord(color) - of "R": - prom = WRook * ord(color) - of "B": - prom = WBishop * ord(color) - of "N": - prom = WKnight * ord(color) - move = getMove(start, dest, prom, color) - return move +proc genPawnAttackDests(game: Game, field: int, color: Color): seq[int] = + ## Generate possible attack destinations for a pawn with specific `color` + ## located at index `field` of `game`. + ## Returns a sequence of possible indices to move to. + if (not field in game.board.low..game.board.high): + return @[] + var res = newSeq[int]() + var dest: int + var target: int + for attacks in Pawn_Moves_White_Attack: + dest = field + (attacks * ord(color)) + if (not dest in game.board.low..game.board.high): + continue + target = game.board[dest] + if (target == 999 or ord(color) * target >= 0): + continue + res.add(dest) + return res + +proc genPawnDoubleDests(game: Game, field: int, color: Color): seq[int] = + ## Generate possible double destinations for a pawn with specific `color` + ## located at index `field` of `game`. + ## Returns a sequence of possible indices to move to. + if (not field in game.board.low..game.board.high): + return @[] + var res = newSeq[int]() + var dest: int + var target: int + for doubles in Pawn_Moves_White_Double: + dest = field + doubles * ord(color) + if (not dest in game.board.low..game.board.high): + continue + target = game.board[dest] + if (game.moved[field] or (target != 0) or ( + game.board[dest+(S*ord(color))] != 0)): + continue + res.add(dest) + return res + +proc genPawnDests(game: Game, field: int, color: Color): seq[int] = + ## Generate possible destinations for a pawn with specific `color` located at + ## index `field` of `game`. + ## Returns a sequence of possible indices to move to. + if (not field in game.board.low..game.board.high): + return @[] + var res = newSeq[int]() + var dest: int + var target: int + for move in Pawn_Moves_White: + dest = field + move * ord(color) + if (not dest in game.board.low..game.board.high): + continue + target = game.board[dest] + if (target != 0 and target != ord(color) * WEnPassant): + continue + res.add(dest) + res.add(game.genPawnAttackDests(field, color)) + res.add(game.genPawnDoubleDests(field, color)) + return res + +proc genKnightDests(game: Game, field: int, color: Color): seq[int] = + ## Generate possible destinations for a knight with specific `color` located + ## at index `field` of `game`. + ## Returns a sequence of possible indices to move to. + if (not field in game.board.low..game.board.high): + return @[] + var res = newSeq[int]() + var dest: int + var target: int + for move in Knight_Moves: + dest = field + move + if (not dest in game.board.low..game.board.high): + continue + target = game.board[dest] + if (target == 999 or (ord(color) * target > 0 and ord(color) * target != WEnPassant)): + continue + res.add(dest) + return res proc genBishopDests(game: Game, field: int, color: Color): seq[int] = ## Generate possible destinations for a bishop with specific `color` located @@ -461,85 +497,6 @@ proc genKingDests(game: Game, field: int, color: Color): seq[int] = res.add(game.genKingCastleDest(field, color)) return res -proc genKnightDests(game: Game, field: int, color: Color): seq[int] = - ## Generate possible destinations for a knight with specific `color` located - ## at index `field` of `game`. - ## Returns a sequence of possible indices to move to. - if (not field in game.board.low..game.board.high): - return @[] - var res = newSeq[int]() - var dest: int - var target: int - for move in Knight_Moves: - dest = field + move - if (not dest in game.board.low..game.board.high): - continue - target = game.board[dest] - if (target == 999 or (ord(color) * target > 0 and ord(color) * target != WEnPassant)): - continue - res.add(dest) - return res - -proc genPawnAttackDests(game: Game, field: int, color: Color): seq[int] = - ## Generate possible attack destinations for a pawn with specific `color` - ## located at index `field` of `game`. - ## Returns a sequence of possible indices to move to. - if (not field in game.board.low..game.board.high): - return @[] - var res = newSeq[int]() - var dest: int - var target: int - for attacks in Pawn_Moves_White_Attack: - dest = field + (attacks * ord(color)) - if (not dest in game.board.low..game.board.high): - continue - target = game.board[dest] - if (target == 999 or ord(color) * target >= 0): - continue - res.add(dest) - return res - -proc genPawnDoubleDests(game: Game, field: int, color: Color): seq[int] = - ## Generate possible double destinations for a pawn with specific `color` - ## located at index `field` of `game`. - ## Returns a sequence of possible indices to move to. - if (not field in game.board.low..game.board.high): - return @[] - var res = newSeq[int]() - var dest: int - var target: int - for doubles in Pawn_Moves_White_Double: - dest = field + doubles * ord(color) - if (not dest in game.board.low..game.board.high): - continue - target = game.board[dest] - if (game.moved[field] or (target != 0) or ( - game.board[dest+(S*ord(color))] != 0)): - continue - res.add(dest) - return res - -proc genPawnDests(game: Game, field: int, color: Color): seq[int] = - ## Generate possible destinations for a pawn with specific `color` located at - ## index `field` of `game`. - ## Returns a sequence of possible indices to move to. - if (not field in game.board.low..game.board.high): - return @[] - var res = newSeq[int]() - var dest: int - var target: int - for move in Pawn_Moves_White: - dest = field + move * ord(color) - if (not dest in game.board.low..game.board.high): - continue - target = game.board[dest] - if (target != 0 and target != ord(color) * WEnPassant): - continue - res.add(dest) - res.add(game.genPawnAttackDests(field, color)) - res.add(game.genPawnDoubleDests(field, color)) - return res - proc pieceOn(game: Game, color: Color, sequence: seq[int], pieceID: int): bool = ## Returns true if the `PieceID` of a given `color` is in `sequence` else @@ -593,11 +550,31 @@ proc moveLeadsToCheck(game: Game, start: int, dest: int, check.uncheckedMove(start, dest) return check.isInCheck(color) -proc removeEnPassant(board: var Board, color: Color): void = - ## Removes every en passant of given `color` from the `board`. - for field in board.low..board.high: - if board[field] == ord(color) * WEnPassant: - board[field] = 0 +proc genPawnPromotion(move: Move, color: Color): seq[Move] = + ## Generate all possible promotions of a `move` by `color`. + var promotions = newSeq[Move]() + let start = move.start + let dest = move.dest + if (90 < dest and dest < 99) or (20 < dest and dest < 29): + for piece in WKnight..WQueen: + promotions.add(getMove(start, dest, piece, color)) + return promotions + +proc genLegalPawnMoves(game: Game, field: int, color: Color): seq[Move] = + ## Generates all legal pawn moves in a `game` starting from `field` for a + ## `color`. + if game.board[field] != WPawn * ord(color): + return @[] + var res = newSeq[Move]() + var moves = game.genPawnDests(field, color) + for dest in moves: + if not game.moveLeadsToCheck(field, dest, color): + var promotions = genPawnPromotion(getMove(field, dest, color), color) + if promotions != @[]: + res.add(promotions) + else: + res.add(getMove(field, dest, color)) + return res proc genLegalKnightMoves(game: Game, field: int, color: Color): seq[Move] = ## Generates all legal knight moves in a `game` starting from `field` for a @@ -663,32 +640,6 @@ proc genLegalKingMoves(game: Game, field: int, color: Color): seq[Move] = res.add(getMove(field, dest, color)) return res -proc genPawnPromotion(move: Move, color: Color): seq[Move] = - ## Generate all possible promotions of a `move` by `color`. - var promotions = newSeq[Move]() - let start = move.start - let dest = move.dest - if (90 < dest and dest < 99) or (20 < dest and dest < 29): - for piece in WKnight..WQueen: - promotions.add(getMove(start, dest, piece, color)) - return promotions - -proc genLegalPawnMoves(game: Game, field: int, color: Color): seq[Move] = - ## Generates all legal pawn moves in a `game` starting from `field` for a - ## `color`. - if game.board[field] != WPawn * ord(color): - return @[] - var res = newSeq[Move]() - var moves = game.genPawnDests(field, color) - for dest in moves: - if not game.moveLeadsToCheck(field, dest, color): - var promotions = genPawnPromotion(getMove(field, dest, color), color) - if promotions != @[]: - res.add(promotions) - else: - res.add(getMove(field, dest, color)) - return res - proc genLegalMoves*(game: Game, field: int, color: Color): seq[Move] = ## Generates all legal moves in a `game` starting from `field` for a `color`. var legal_moves = newSeq[Move]() @@ -756,6 +707,12 @@ proc castling(game: var Game, kstart: int, dest_kingside: bool, return true return false +proc removeEnPassant(board: var Board, color: Color): void = + ## Removes every en passant of given `color` from the `board`. + for field in board.low..board.high: + if board[field] == ord(color) * WEnPassant: + board[field] = 0 + proc checkedMove*(game: var Game, move: Move): bool {.discardable.} = ## Tries to make a `move` in a given `game``. ## This process checks for the legality of the move and performs the switch @@ -833,6 +790,48 @@ proc isDrawClaimable*(game: Game): bool = ## Returns true if a draw is claimable by either player. return game.threeMoveRep() or game.fiftyMoveRule() +proc checkInsufficientMaterial(board: Board): bool = + ## Checks for combinations of pieces on a `board`, where no checkmate can be + ## forced. + ## Returns true if no player can force a checkmate to the other. + var wp = 0 + var wn = 0 + var wb = 0 + var wr = 0 + var wq = 0 + var bp = 0 + var bn = 0 + var bb = 0 + var br = 0 + var bq = 0 + for field in board.low..board.high: + case board[field]: + of WPawn: + wp = wp + 1 + of BPawn: + bp = bp + 1 + of WKnight: + wn = wn + 1 + of BKnight: + bn = bn + 1 + of WBishop: + wb = wb + 1 + of BBishop: + bb = bb + 1 + of WRook: + wr = wr + 1 + of BRook: + br = br + 1 + of WQueen: + wq = wq + 1 + of BQueen: + bq = bq + 1 + else: + continue + let wpieces: PieceAmount = (wp, wn, wb, wr, wq) + let bpieces: PieceAmount = (bp, bn, bb, br, bq) + return (wpieces in InsufficientMaterial) and (bpieces in InsufficientMaterial) + proc isStalemate*(game: Game, color: Color): bool = ## Returns true if the `color` player is stalemate in a `game`. return (game.hasNoMoves(color) and not game.isInCheck(color)) or diff --git a/src/game.nim b/src/game.nim index ddbf06c..3d10636 100644 --- a/src/game.nim +++ b/src/game.nim @@ -1,6 +1,3 @@ -from strutils import parseInt -import rdstdin - import ./chess proc runGame*(): void = diff --git a/src/test.nim b/src/gameTest.nim similarity index 100% rename from src/test.nim rename to src/gameTest.nim