diff --git a/chess.nim b/chess.nim index a899b89..912b39e 100644 --- a/chess.nim +++ b/chess.nim @@ -10,9 +10,15 @@ type Moved* = array[0..119, bool] ## Game as object of different values Game* = object - pieces: Pieces + pieces*: Pieces moved: Moved - to_move: Color + to_move*: Color + ## Move as object + Move* = object + start: int + dest: int + color: Color + prom: int const # IDs for piece @@ -51,6 +57,7 @@ const Rook_Moves = [N, E, S, W] Queen_Moves = [N, E, S, W, N+E, N+W, S+E, S+W] King_Moves = [N, E, S, W, N+E, N+W, S+E, S+W] + King_Moves_White_Castle = [E+E, W+W] Pawn_Moves_White = [N] Pawn_Moves_White_Double = [N+N] Pawn_Moves_White_Attack = [N+E, N+W] @@ -102,6 +109,18 @@ proc init_board(): Pieces = Block, Block, Block, Block, Block, Block, Block, Block, Block, Block] return board +proc get_move*(start: int, dest: int, prom: int, color: Color): Move = + ## Get a move object from `start` to `dest` with an eventual promition to `prom` + var move = Move(start: start, dest: dest, prom: prom * ord(color), color: color) + if (KnightID > prom or QueenID < prom): + move.prom = QueenID + return move + +proc get_move*(start: int, dest: int, color: Color): Move = + ## Get a move object from `start` to `dest` with automatic promition to `queen` + var move = Move(start: start, dest: dest, prom: QueenID * ord(color), color: color) + return move + proc init_moved(): Moved = ## Create and return a board of pieces moved. var moved: Moved @@ -113,7 +132,7 @@ proc init_game*(): Game = to_move: Color.White) return game -proc get_field*(pieces: Pieces, field: int): int = +proc get_field(pieces: Pieces, field: int): int = return pieces[field] proc set_field(pieces: var Pieces, field: int, val: int): bool {.discardable.} = @@ -124,7 +143,7 @@ proc set_field(pieces: var Pieces, field: int, val: int): bool {.discardable.} = except Exception: return false -proc get_field*(moved: Moved, field: int): bool = +proc get_field(moved: Moved, field: int): bool = return moved[field] proc set_field(moved: var Moved, field: int, val: bool): bool {.discardable.} = @@ -178,8 +197,8 @@ proc ind_to_field*(ind: int): string = if FileChar[file] == file_ind: return $file & $line -proc gen_bishop_moves(game: Game, field: int, color: Color): seq[int] = - ## Generate possible moves for a bishop with specific `color` located at index `field` of `board`. +proc gen_bishop_dests(game: Game, field: int, color: Color): seq[int] = + ## Generate possible destinations for a bishop with specific `color` located at index `field` of `game`. ## Returns a sequence of possible indices to move to. try: var res = newSeq[int]() @@ -198,8 +217,8 @@ proc gen_bishop_moves(game: Game, field: int, color: Color): seq[int] = except IndexDefect: return @[] -proc gen_rook_moves(game: Game, field: int, color: Color): seq[int] = - ## Generate possible moves for a rook with specific `color` located at index `field` of `board`. +proc gen_rook_dests(game: Game, field: int, color: Color): seq[int] = + ## Generate possible destinations for a rook with specific `color` located at index `field` of `game`. ## Returns a sequence of possible indices to move to. try: var res = newSeq[int]() @@ -218,8 +237,8 @@ proc gen_rook_moves(game: Game, field: int, color: Color): seq[int] = except IndexDefect: return @[] -proc gen_queen_moves(game: Game, field: int, color: Color): seq[int] = - ## Generate possible moves for a queen with specific `color` located at index `field` of `board`. +proc gen_queen_dests(game: Game, field: int, color: Color): seq[int] = + ## Generate possible destinations for a queen with specific `color` located at index `field` of `game`. ## Returns a sequence of possible indices to move to. try: var res = newSeq[int]() @@ -238,8 +257,32 @@ proc gen_queen_moves(game: Game, field: int, color: Color): seq[int] = except IndexDefect: return @[] -proc gen_king_moves(game: Game, field: int, color: Color): seq[int] = - ## Generate possible moves for a king with specific `color` located at index `field` of `board`. +proc gen_king_castle_dest(game: Game, field: int, color: Color): seq[int] = + ## Generate possible castle destinations for a king with specific `color` located at index `field` of `game` + ## Returns a sequence of possible indices to move to. + try: + var res = newSeq[int]() + var dest: int + var target: int + var half_dest: int + var half_target: int + for castle in King_Moves_White_Castle: + dest = field + castle + target = game.pieces.get_field(dest) + half_dest = field + (int) castle/2 + half_target = game.pieces.get_field(half_dest) + if (target == 999 or (target != 0)): + continue + if (half_target == 999 or (half_target != 0)): + continue + res.add(dest) + return res + except IndexDefect: + return @[] + + +proc gen_king_dests(game: Game, field: int, color: Color): seq[int] = + ## Generate possible destinations for a king with specific `color` located at index `field` of `game`. ## Returns a sequence of possible indices to move to. try: var res = newSeq[int]() @@ -251,12 +294,13 @@ proc gen_king_moves(game: Game, field: int, color: Color): seq[int] = if (target == 999 or (ord(color) * target > 0 and ord(color) * target != EnPassantID)): continue res.add(dest) + res.add(game.gen_king_castle_dest(field, color)) return res except IndexDefect: return @[] -proc gen_knight_moves(game: Game, field: int, color: Color): seq[int] = - ## Generate possible moves for a knight with specific `color` located at index `field` of `board`. +proc gen_knight_dests(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. try: var res = newSeq[int]() @@ -272,8 +316,8 @@ proc gen_knight_moves(game: Game, field: int, color: Color): seq[int] = except IndexDefect: return @[] -proc gen_pawn_attacks(game: Game, field: int, color: Color): seq[int] = - ## Generate possible attacks for a pawn with specific `color` located at index `field` of `board`. +proc gen_pawn_attack_dests(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. try: var res = newSeq[int]() @@ -289,8 +333,8 @@ proc gen_pawn_attacks(game: Game, field: int, color: Color): seq[int] = except IndexDefect: return @[] -proc gen_pawn_doubles(game: Game, field: int, color: Color): seq[int] = - ## Generate possible double moves for a pawn with specific `color` located at index `field` of `board`. +proc gen_pawn_double_dests(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. try: var res = newSeq[int]() @@ -306,8 +350,8 @@ proc gen_pawn_doubles(game: Game, field: int, color: Color): seq[int] = except IndexDefect: return @[] -proc gen_pawn_moves(game: Game, field: int, color: Color): seq[int] = - ## Generate possible moves for a pawn with specific `color` located at index `field` of `board`. +proc gen_pawn_dests(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. try: var res = newSeq[int]() @@ -319,8 +363,8 @@ proc gen_pawn_moves(game: Game, field: int, color: Color): seq[int] = if (target != 0 and target != ord(color) * EnPassantID): continue res.add(dest) - res.add(game.gen_pawn_attacks(field, color)) - res.add(game.gen_pawn_doubles(field, color)) + res.add(game.gen_pawn_attack_dests(field, color)) + res.add(game.gen_pawn_double_dests(field, color)) return res except IndexDefect: return @[] @@ -336,21 +380,21 @@ proc piece_on(game: Game, color: Color, sequence: seq[int], proc is_attacked(game: Game, position: int, color: Color): bool = ## Check if a field is attacked by the opposite of `color` in a `game`. var attacked = false - attacked = attacked or game.piece_on(color, game.gen_pawn_attacks(position, + attacked = attacked or game.piece_on(color, game.gen_pawn_attack_dests(position, color), PawnID) - attacked = attacked or game.piece_on(color, game.gen_queen_moves(position, + attacked = attacked or game.piece_on(color, game.gen_queen_dests(position, color), QueenID) - attacked = attacked or game.piece_on(color, game.gen_king_moves(position, + attacked = attacked or game.piece_on(color, game.gen_king_dests(position, color), KingID) - attacked = attacked or game.piece_on(color, game.gen_rook_moves(position, + attacked = attacked or game.piece_on(color, game.gen_rook_dests(position, color), RookID) - attacked = attacked or game.piece_on(color, game.gen_bishop_moves(position, + attacked = attacked or game.piece_on(color, game.gen_bishop_dests(position, color), BishopID) - attacked = attacked or game.piece_on(color, game.gen_knight_moves(position, + attacked = attacked or game.piece_on(color, game.gen_knight_dests(position, color), KnightID) return attacked -proc is_in_check(game: Game, color: Color): bool = +proc is_in_check*(game: Game, color: Color): bool = ## Check if the King of a given `color` is in check in a `game`. var king_pos: int for i in countup(0, game.pieces.high): @@ -358,7 +402,7 @@ proc is_in_check(game: Game, color: Color): bool = king_pos = i return game.is_attacked(king_pos, color) -proc simple_move(game: var Game, start: int, dest: int): bool {.discardable.} = +proc unchecked_move(game: var Game, start: int, dest: int): bool {.discardable.} = ## Moves a piece if possible from `start` position to `dest` position. ## Doesnt check boundaries, checks, movement. ## returns true if the piece moved, else false @@ -376,9 +420,9 @@ proc simple_move(game: var Game, start: int, dest: int): bool {.discardable.} = proc move_leads_to_check(game: Game, start: int, dest: int, color: Color): bool = - ## Checks in a game if a move from `start` to `dest` puts the `color` king in check. + ## Checks in a `game` if a move from `start` to `dest` puts the `color` king in check. var check = game - check.simple_move(start, dest) + check.unchecked_move(start, dest) return check.is_in_check(color) proc remove_en_passant(pieces: var Pieces, color: Color): void = @@ -387,58 +431,120 @@ proc remove_en_passant(pieces: var Pieces, color: Color): void = if pieces.get_field(field) == ord(color) * EnPassantID: pieces.set_field(field,0) -proc checked_move*(game: var Game, start: int, dest: int, color: Color): bool {.discardable.} = - ## Tries to make a move in a given `game` with the piece of a given `color` from `start` to `dest`. - ## This process checks for the legality of the move and performs the switch of `game.to_move` - try: - if game.to_move != color: - return false - var sequence = newSeq[int]() - let piece = game.pieces.get_field(start) - var create_en_passant = false - var captured_en_passant = false - if (piece == PawnID * ord(color)): - sequence.add(game.gen_pawn_moves(start, color)) - create_en_passant = dest in game.gen_pawn_doubles(start,color) - captured_en_passant = (game.pieces.get_field(dest) == -1 * ord(color) * EnPassantID) - if (piece == KnightID * ord(color)): - sequence.add(game.gen_knight_moves(start, color)) - if (piece == BishopID * ord(color)): - sequence.add(game.gen_bishop_moves(start, color)) - if (piece == RookID * ord(color)): - sequence.add(game.gen_rook_moves(start, color)) - if (piece == QueenID * ord(color)): - sequence.add(game.gen_queen_moves(start, color)) - if (piece == KingID * ord(color)): - sequence.add(game.gen_king_moves(start, color)) - if (dest in sequence) and not game.move_leads_to_check(start, dest, color): - game.pieces.remove_en_passant(color) - game.simple_move(start, dest) - game.to_move = Color(ord(game.to_move)*(-1)) - if create_en_passant: - game.pieces.set_field(dest-(N*ord(color)),EnPassantID * ord(color)) - if captured_en_passant: - game.pieces.set_field(dest-(N*ord(color)),0) - return true - except IndexDefect, ValueError: - return false +proc gen_legal_knight_moves(game: Game, field: int, color: Color): seq[Move] = + ## Generates all legal knight moves starting from `field` in a `game` for a `color`. + if game.pieces.get_field(field) != KnightID * ord(color): + return @[] + var res = newSeq[Move]() + var moves = game.gen_knight_dests(field, color) + for dest in moves: + if not game.move_leads_to_check(field, dest, color): + res.add(get_move(field, dest, color)) + return res + +proc gen_legal_bishop_moves(game: Game, field: int, color: Color): seq[Move] = + ## Generates all legal bishop moves starting from `field` in a `game` for a `color`. + if game.pieces.get_field(field) != BishopID * ord(color): + return @[] + var res = newSeq[Move]() + var moves = game.gen_bishop_dests(field, color) + for dest in moves: + if not game.move_leads_to_check(field, dest, color): + res.add(get_move(field, dest, color)) + return res + +proc gen_legal_rook_moves(game: Game, field: int, color: Color): seq[Move] = + ## Generates all legal rook moves starting from `field` in a `game` for a `color`. + if game.pieces.get_field(field) != RookID * ord(color): + return @[] + var res = newSeq[Move]() + var moves = game.gen_rook_dests(field, color) + for dest in moves: + if not game.move_leads_to_check(field, dest, color): + res.add(get_move(field, dest, color)) + return res + +proc gen_legal_queen_moves(game: Game, field: int, color: Color): seq[Move] = + ## Generates all legal queen moves starting from `field` in a `game` for a `color`. + if game.pieces.get_field(field) != QueenID * ord(color): + return @[] + var res = newSeq[Move]() + var moves = game.gen_queen_dests(field, color) + for dest in moves: + if not game.move_leads_to_check(field, dest, color): + res.add(get_move(field, dest, color)) + return res + +proc gen_legal_king_moves(game: Game, field: int, color: Color): seq[Move] = + ## Generates all legal king moves starting from `field` in a `game` for a `color`. + if game.pieces.get_field(field) != KingID * ord(color): + return @[] + var res = newSeq[Move]() + var moves = game.gen_king_dests(field, color) + for dest in moves: + if field - dest == W+W and game.is_attacked(dest+W, color): + continue + if field - dest == E+E and game.is_attacked(dest+E, color): + continue + if not game.move_leads_to_check(field, dest, color): + res.add(get_move(field, dest, color)) + return res + +proc gen_pawn_promotion(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 KnightID..QueenID: + promotions.add(get_move(start, dest, piece, color)) + return promotions + +proc gen_legal_pawn_moves(game: Game, field: int, color: Color): seq[Move] = + ## Generates all legal pawn moves starting from `field` in a `game` for a `color`. + if game.pieces.get_field(field) != PawnID * ord(color): + return @[] + var res = newSeq[Move]() + var moves = game.gen_pawn_dests(field, color) + for dest in moves: + if not game.move_leads_to_check(field, dest, color): + var promotions = gen_pawn_promotion(get_move(field, dest, color), color) + if promotions != @[]: + res.add(promotions) + else: + res.add(get_move(field, dest, color)) + return res + +proc gen_legal_moves*(game: Game, field: int, color: Color): seq[Move] = + ## Generates all legal moves starting from `field` in a `game` for a `color`. + var legal_moves = newSeq[Move]() + var target = ord(color) * game.pieces.get_field(field) + if 0 < target and target < EnPassantID: + legal_moves = case target: + of PawnID: + game.gen_legal_pawn_moves(field, color) + of KnightID: + game.gen_legal_knight_moves(field, color) + of BishopID: + game.gen_legal_bishop_moves(field, color) + of RookID: + game.gen_legal_rook_moves(field, color) + of QueenID: + game.gen_legal_queen_moves(field, color) + of KingID: + game.gen_legal_king_moves(field, color) + else: + @[] + return legal_moves -proc checked_promotion*(game: var Game, start: int, dest: int, color: Color, - prom: int): bool {.discardable.} = - ## Tries to make a promotion to `prom` in a given `game` with the piece of a given `color` from `start` to `dest`. - ## This process checks for the legality of the move and performs the switch of `game.to_move` - try: - if game.pieces.get_field(start) != PawnID * ord(color) or (1 > prom or - prom > 5): - return false - if (90 < dest and dest < 99) or (20 < dest and dest < 29): - if (game.checked_move(start, dest, color)): - game.pieces.set_field(dest, prom) - return false - except IndexDefect, ValueError: - return false +proc gen_legal_moves*(game: Game, color: Color): seq[Move] = + ## Generates all legal moves in a `game` for a `color`. + var legal_moves = newSeq[Move]() + for field in game.pieces.low..game.pieces.high: + legal_moves.add(game.gen_legal_moves(field, color)) + return legal_moves -proc castling*(game: var Game, kstart: int, dest_kingside: bool, +proc castling(game: var Game, kstart: int, dest_kingside: bool, color: Color): bool {.discardable.} = ## Tries to castle in a given `game` with the king of a given `color` from `start`. ## `dest_kingside` for kingside castling, else castling is queenside. @@ -450,57 +556,74 @@ proc castling*(game: var Game, kstart: int, dest_kingside: bool, var rstart: int var rdest: int if (dest_kingside): - kdest = kstart + (E+E) * ord(color) - rstart = kstart + (E+E+E) * ord(color) - rdest = rstart + (W+W) * ord(color) + kdest = kstart + (E+E) + rstart = kstart + (E+E+E) + rdest = rstart + (W+W) else: - rstart = kstart + (W+W+W+W) * ord(color) - rdest = rstart + (E+E+E) * ord(color) - kdest = kstart + (W+W) * ord(color) + rstart = kstart + (W+W+W+W) + rdest = rstart + (E+E+E) + kdest = kstart + (W+W) if not game.moved.get_field(kstart) and not game.moved.get_field(rstart): var check = false if (dest_kingside): check = check or game.is_attacked(kstart, color) - check = check or game.is_attacked(kstart+(E)*ord(color), color) - check = check or game.is_attacked(kstart+(E+E)*ord(color), color) + check = check or game.is_attacked(kstart+(E), color) + check = check or game.is_attacked(kstart+(E+E), color) else: check = check or game.is_attacked(kstart, color) - check = check or game.is_attacked(kstart+(W)*ord(color), color) - check = check or game.is_attacked(kstart+(W+W)*ord(color), color) + check = check or game.is_attacked(kstart+(W), color) + check = check or game.is_attacked(kstart+(W+W), color) if check: return false - game.simple_move(kstart, kdest) - game.simple_move(rstart, rdest) + game.unchecked_move(kstart, kdest) + game.unchecked_move(rstart, rdest) + return true return false except IndexDefect, ValueError: return false +proc checked_move*(game: var Game, move: Move): bool {.discardable.} = + ## Tries to make a move in a given `game` with the piece of a given `color` from `start` to `dest`. + ## This process checks for the legality of the move and performs the switch of `game.to_move` + try: + let start = move.start + let dest = move.dest + let color = move.color + let prom = move.prom + if game.to_move != color: + return false + var sequence = newSeq[Move]() + let piece = game.pieces.get_field(start) + var create_en_passant = false + var captured_en_passant = false + var move: Move + move = get_move(start, dest, color) + if (piece == PawnID * ord(color)): + create_en_passant = dest in game.gen_pawn_double_dests(start,color) + captured_en_passant = (game.pieces.get_field(dest) == -1 * ord(color) * EnPassantID) + sequence.add(game.gen_legal_moves(start, color)) + if (move in sequence): + game.pieces.remove_en_passant(color) + if (piece == KingID * ord(color) and (start - dest == (W+W))): + game.castling(start, true, color) + elif (piece == KingID * ord(color) and (start - dest == (E+E))): + game.castling(start, false, color) + else: + game.unchecked_move(start, dest) + game.to_move = Color(ord(game.to_move)*(-1)) + if create_en_passant: + game.pieces.set_field(dest-(N*ord(color)),EnPassantID * ord(color)) + if captured_en_passant: + game.pieces.set_field(dest-(N*ord(color)),0) + if ((90 < dest and dest < 99) or (20 < dest and dest < 29)) and game.pieces.get_field(dest) == PawnID * ord(color): + game.pieces.set_field(dest, prom) + return true + except IndexDefect, ValueError: + return false + proc has_no_moves(game: Game, color: Color): bool = ## Checks if a player of a given `color` has no legal moves in a `game`. - var sequence = newSeq[(int,int)]() - for field_ind in game.pieces.low..game.pieces.high: - var target = ord(color) * game.pieces.get_field(field_ind) - if 0 < target and target < EnPassantID: - var possibilities = newSeq[int]() - case target: - of PawnID: - possibilities = game.gen_pawn_moves(field_ind, color) - of KnightID: - possibilities = game.gen_knight_moves(field_ind, color) - of BishopID: - possibilities = game.gen_bishop_moves(field_ind, color) - of RookID: - possibilities = game.gen_rook_moves(field_ind, color) - of QueenID: - possibilities = game.gen_queen_moves(field_ind, color) - of KingID: - possibilities = game.gen_king_moves(field_ind, color) - else: - continue - for dest in possibilities: - if (not game.move_leads_to_check(field_ind,dest,color)): - return false - return true + return (game.gen_legal_moves(color) == @[]) proc is_checkmate*(game: Game, color: Color): bool = ## Checks if a player of a given `color` in a `game` is checkmate. diff --git a/game.nim b/game.nim index dab1f9e..e60c4ee 100644 --- a/game.nim +++ b/game.nim @@ -1,12 +1,46 @@ +from strutils import parseInt +import rdstdin + import ./chess -# Testing +proc notation_to_move(notation: string, color: Color): Move = + ## Convert simplified algebraic chess `notation` to a move object, color of player is `color`. + try: + var move: Move + var start = field_to_ind(notation[0..1]) + var dest = field_to_ind(notation[2..3]) + move = get_move(start, dest, color) + if (len(notation) > 4): + var prom_str = $notation[4] + var prom: int + case prom_str: + of "Q": + prom = QueenID * ord(color) + of "R": + prom = RookID * ord(color) + of "B": + prom = BishopID * ord(color) + of "N": + prom = KnightID * ord(color) + move = get_move(start, dest, prom, color) + return move + except IndexError: + var move: Move + return move + +proc run_game(): void = + var game = init_game() + game.echo_board(game.to_move) + while not game.is_checkmate(game.to_move): + echo "Make a move" + echo game.to_move + var move = readLine(stdin) + while not game.checked_move(notation_to_move(move, game.to_move)): + move = readLine(stdin) + game.echo_board(game.to_move) + if game.is_checkmate(game.to_move): + echo $game.to_move & " was checkmated" + if game.is_stalemate(game.to_move): + echo "Stalemate" -var game = chess.init_game() -game.checked_move(field_to_ind("e2"),field_to_ind("e4"),Color.White) -game.checked_move(field_to_ind("e7"),field_to_ind("e6"),Color.Black) -game.checked_move(field_to_ind("g2"),field_to_ind("g4"),Color.White) -game.checked_move(field_to_ind("d8"),field_to_ind("h4"),Color.Black) -game.echo_board(Color.White) -echo game.is_checkmate(Color.White) -echo game.is_stalemate(Color.White) +run_game()