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chess: updating documentation 

Documentation is now set for every method with complete parameters.
Also all global variables and constants as well as types are documented.
master
TiynGER 1 week ago
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9b68538b12
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6ad11fde2a
2 changed files with 131 additions and 92 deletions
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@ -10,9 +10,8 @@ type
## `Board` saves the position of the chess pieces.
Moved* = array[0..119, bool] ## \
## `Moved` saves the position of squares a piece moved on or from.
CastleRights = tuple
# `CastleRights` contains the rights to castling for each player.
## `CastleRights` contains the rights to castling for each player.
wk: bool # `wk` describes White kingside castle
wq: bool # `wq` describes White queenside castle
bk: bool # `bk` describes Black kingside castle
@ -32,8 +31,8 @@ type
color: Color
prom: int
PieceAmount = tuple
# `PieceAmount` describes the number of pieces of a certain type a/both
# player/s has/have.
## `PieceAmount` describes the number of pieces of a certain type a/both
## player/s has/have.
p: int # `p` describes the amount of pawns.
n: int # `n` describes the amount of knights.
b: int # `b` describes the amount of bishops.
@ -41,69 +40,79 @@ type
q: int # `q` describes the amount of queens.
const
Block* = 999 ## \
Block* = 999 ## \
## `Block` is the value assigned to empty blocked fields in a board.
WPawn* = 1
## `WPawn` is the value assigned to a square in a board with a white pawn.
WKnight* = 2 ## \
WKnight* = 2 ## \
## `WKnight` is the value assigned to a square in a board with a white
## knight.
WBishop* = 3 ## \
WBishop* = 3 ## \
## `WBishop` is the value assigned to a square in a board with a white
## bishop.
WRook* = 4 ## \
WRook* = 4 ## \
## `WRook` is the value assigned to a square in a board with a white rook.
WQueen* = 5 ## \
WQueen* = 5 ## \
## `WQueen` is the value assigned to a square in a board with a white
## queen.
WKing* = 6 ## \
WKing* = 6 ## \
## `WKing` is the value assigned to a square in a board with a white king.
WEnPassant* = 7 ## \
WEnPassant* = 7 ## \
## `WEnPassant` is assigned to a square in a board with an invisible white
## en passant pawn.
BPawn* = -WPawn ## \
BPawn* = -WPawn ## \
## `BPawn` is the value assigned to a square in a board with a black pawn.
BKnight* = -WKnight ## \
BKnight* = -WKnight ## \
## `BKnight` is the value assigned to a square in a board with a black\
## knight.
BBishop* = -WBishop ## \
BBishop* = -WBishop ## \
## `BBishop` is the value assigned to a square in a board with a black\
## bishop.
BRook* = -WRook ## \
BRook* = -WRook ## \
## `BRook` is the value assigned to a square in a board with a black rook.
BQueen* = -WQueen ## \
BQueen* = -WQueen ## \
## `BQueen` is the value assigned to a square in a board with a black queen.
BKing* = -WKing ## \
BKing* = -WKing ## \
## `BKing` is the value assigned to a square in a board with a black king.
BEnPassant* = -WEnPassant ## \
BEnPassant* = -WEnPassant ## \
## `BEnPassant` is assigned to a square in a board with an invisible black
## en passant pawn.
# Directions of squares from whites perspective.
N = 10 # move up
S = -N # Move down
W = 1 # Move left
E = -W # Move right
N = 10 ## `N` describes a move a field up the board from whites perspective.
S = -N ## `S` describes a move a field down the board from whites perspective.
W = 1 ## `W` describes a move a field to the left from whites perspective.
E = -W ## `E` describes a move a field to the right from whites perspective.
# Directions for the pieces. Special moves are in separate arrays.
Knight_Moves = [N+N+E, N+N+W, E+E+N, E+E+S, S+S+E, S+S+W, W+W+N, W+W+S]
Bishop_Moves = [N+E, N+W, S+E, S+W]
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]
# Material as PieceAmount where a forced checkmate is not possible.
InsufficientMaterial: array[4,PieceAmount] = [
(0, 0, 0, 0, 0), # only kings
(0, 0, 1, 0, 0), # knight only
(0, 1, 0, 0, 0), # bishop only
(0, 2, 0, 0, 0) # 2 knights
]
Knight_Moves = [N+N+E, N+N+W, E+E+N, E+E+S, S+S+E, S+S+W, W+W+N, W+W+S] ## \
## `Knight_Moves` describes the possible knight moves.
Bishop_Moves = [N+E, N+W, S+E, S+W] ## \
## `Bishop_Moves` describes the possible 1 field distance bishop moves.
Rook_Moves = [N, E, S, W] ## \
## `Rook_Moves` describes the possible 1 field distance rook moves.
Queen_Moves = [N, E, S, W, N+E, N+W, S+E, S+W] ## \
## `Queen_Moves` describes the possible 1 field distance queen moves.
King_Moves = [N, E, S, W, N+E, N+W, S+E, S+W] ## \
## `King_Moves` describes the possible 1 field distance king moves.
King_Moves_White_Castle = [E+E, W+W] ## \
## `King_Moves` describes the possible king moves for castling.
Pawn_Moves_White = [N] ## \
## `Pawn_Moves_White` describes the possible 1 field distance pawn moves
## from whites perspective that are not attacks.
Pawn_Moves_White_Double = [N+N] ## \
## `Pawn_Moves_White_Double` describes the possible pawn 2 field distance
## moves from whites perspective.
Pawn_Moves_White_Attack = [N+E, N+W] ## \
## `Pawn_Moves_White` describes the possible 1 field distance pawn moves
## from whites perspective that are ttacks.
InsufficientMaterial: array[4, PieceAmount] = [
(0, 0, 0, 0, 0), # only kings
(0, 0, 1, 0, 0), # knight only
(0, 1, 0, 0, 0), # bishop only
(0, 2, 0, 0, 0) # 2 knights
] ## `InsufficientMaterial` describes the pieces where no checkmate can be
## forced.
let
# Representation of the pieces by ID.
PieceChar = {
0: " ",
WPawn: "P",
@ -120,8 +129,8 @@ let
BQueen: "q",
BKing: "k",
BEnPassant: " ",
}.newTable
# Files on the chess board mapped to according integers.
}.newTable ## \
## `PieceChar` describes the representation for the pieceIDs for the cli.
FileChar = {
"a": 7,
"b": 6,
@ -131,10 +140,14 @@ let
"f": 2,
"g": 1,
"h": 0
}.newTable
}.newTable ## \
# `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
## 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
@ -191,7 +204,8 @@ proc initBoard(): Board =
return board
proc initBoard(board: array[0..63, int]): Board =
## Create and return a board with pieces in position of choice
## Create and return a board with pieces in position of choice, described in
## `board`.
let board = [
Block, Block, Block, Block, Block, Block, Block, Block, Block, Block,
Block, Block, Block, Block, Block, Block, Block, Block, Block, Block,
@ -229,6 +243,7 @@ proc initGame*(): Game =
proc initGame*(board: array[0..63, int], color: Color): Game =
## Create ad return a Game object based on a position of choice.
## `board` describes the pieces, `color` the color that is about to move.
let board = initBoard(board)
let compare = initBoard()
var moved = initMoved()
@ -242,19 +257,22 @@ proc initGame*(board: array[0..63, int], color: Color): Game =
return game
proc getMove*(start: int, dest: int, prom: int, color: Color): Move =
## Get a move object from `start` to `dest` with an eventual promition to `prom`
## 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 from `start` to `dest` with automatic promition to `queen`
## 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`.
## Prints out the given `board` with its pieces as characters and line
## indices from perspecive of `color`.
var line_str = ""
if (color == Color.Black):
for i in countup(0, len(game.board)-1):
@ -276,21 +294,23 @@ proc echoBoard*(game: Game, color: Color) =
echo "a b c d e f g h"
proc fieldToInd*(file: string, line: int): int =
## Calculate board index from `file` and `line` of a chess board.
## 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 board index from `field` of a chess board.
## 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 field name from board index `ind`.
## 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:
@ -298,7 +318,7 @@ proc indToField*(ind: int): string =
return $file & $line
proc genCastleRights(moved: Moved): CastleRights =
## Generate rights to castle from given `moved`
## Generate and return rights to castle from given `moved`
let wk = not moved[fieldToInd("e1")] and not moved[fieldToInd("h1")]
let wq = not moved[fieldToInd("e1")] and not moved[fieldToInd("a1")]
let bk = not moved[fieldToInd("e8")] and not moved[fieldToInd("h8")]
@ -306,7 +326,8 @@ proc genCastleRights(moved: Moved): CastleRights =
return (wk, wq, bk, bq)
proc notationToMove*(notation: string, color: Color): Move =
## Convert simplified algebraic chess `notation` to a move object, color of player is `color`.
## 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])
@ -327,7 +348,8 @@ proc notationToMove*(notation: string, color: Color): Move =
return move
proc genBishopDests(game: Game, field: int, color: Color): seq[int] =
## Generate possible destinations for a bishop with specific `color` located at index `field` of `game`.
## Generate possible destinations for a bishop 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 @[]
@ -349,7 +371,8 @@ proc genBishopDests(game: Game, field: int, color: Color): seq[int] =
return res
proc genRookDests(game: Game, field: int, color: Color): seq[int] =
## Generate possible destinations for a rook with specific `color` located at index `field` of `game`.
## Generate possible destinations for a rook 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 @[]
@ -371,7 +394,8 @@ proc genRookDests(game: Game, field: int, color: Color): seq[int] =
return res
proc genQueenDests(game: Game, field: int, color: Color): seq[int] =
## Generate possible destinations for a queen with specific `color` located at index `field` of `game`.
## Generate possible destinations for a queen 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 @[]
@ -393,7 +417,8 @@ proc genQueenDests(game: Game, field: int, color: Color): seq[int] =
return res
proc genKingCastleDest(game: Game, field: int, color: Color): seq[int] =
## Generate possible castle destinations for a king with specific `color` located at index `field` of `game`
## 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.
if (not field in game.board.low..game.board.high):
return @[]
@ -416,9 +441,9 @@ proc genKingCastleDest(game: Game, field: int, color: Color): seq[int] =
res.add(dest)
return res
proc genKingDests(game: Game, field: int, color: Color): seq[int] =
## Generate possible destinations for a king with specific `color` located at index `field` of `game`.
## Generate possible destinations for a king 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 @[]
@ -437,7 +462,8 @@ proc genKingDests(game: Game, field: int, color: Color): seq[int] =
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`.
## 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 @[]
@ -455,7 +481,8 @@ proc genKnightDests(game: Game, field: int, color: Color): seq[int] =
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`.
## 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 @[]
@ -473,7 +500,8 @@ proc genPawnAttackDests(game: Game, field: int, color: Color): seq[int] =
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`.
## 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 @[]
@ -492,7 +520,8 @@ proc genPawnDoubleDests(game: Game, field: int, color: Color): seq[int] =
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`.
## 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 @[]
@ -513,14 +542,16 @@ proc genPawnDests(game: Game, field: int, color: Color): seq[int] =
proc pieceOn(game: Game, color: Color, sequence: seq[int],
pieceID: int): bool =
## Check if a piece with `pieceID` of a given `color` is in a field described in a `sequence` in a `game`.
## Returns true if the `PieceID` of a given `color` is in `sequence` else
## wrong.
for check in sequence:
if game.board[check] == ord(color) * -1 * pieceID:
return true
return false
proc isAttacked(game: Game, position: int, color: Color): bool =
## Check if a field is attacked by the opposite of `color` in a `game`.
## Returns true if a `position` in a `game` is attacked by the opposite
## color of `color`.
var attacked = false
attacked = attacked or game.pieceOn(color, game.genPawnAttackDests(
position, color), WPawn)
@ -537,7 +568,7 @@ proc isAttacked(game: Game, position: int, color: Color): bool =
return attacked
proc isInCheck*(game: Game, color: Color): bool =
## Check if the King of a given `color` is in check in a `game`.
## Returns true if the king of a given `color` is in check in a `game`.
var king_pos: int
for i in countup(0, game.board.high):
if game.board[i] == ord(color) * WKing:
@ -545,9 +576,8 @@ proc isInCheck*(game: Game, color: Color): bool =
return game.isAttacked(king_pos, color)
proc uncheckedMove(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
## Moves a piece if possible from `start` position to `dest` position in a
## `game`.
let piece = game.board[start]
game.board[start] = 0
game.board[dest] = piece
@ -557,19 +587,21 @@ proc uncheckedMove(game: var Game, start: int, dest: int): bool {.discardable.}
proc moveLeadsToCheck(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.
## Returns true if a move from `start` to `dest` in a `game` puts the `color`
## king in check.
var check = game
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 `game`.
## 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 genLegalKnightMoves(game: Game, field: int, color: Color): seq[Move] =
## Generates all legal knight moves starting from `field` in a `game` for a `color`.
## Generates all legal knight moves in a `game` starting from `field` for a
## `color`.
if game.board[field] != WKnight * ord(color):
return @[]
var res = newSeq[Move]()
@ -580,7 +612,8 @@ proc genLegalKnightMoves(game: Game, field: int, color: Color): seq[Move] =
return res
proc genLegalBishopMoves(game: Game, field: int, color: Color): seq[Move] =
## Generates all legal bishop moves starting from `field` in a `game` for a `color`.
## Generates all legal bishop moves in a `game` starting from `field` for a
## `color`.
if game.board[field] != WBishop * ord(color):
return @[]
var res = newSeq[Move]()
@ -591,7 +624,8 @@ proc genLegalBishopMoves(game: Game, field: int, color: Color): seq[Move] =
return res
proc genLegalRookMoves(game: Game, field: int, color: Color): seq[Move] =
## Generates all legal rook moves starting from `field` in a `game` for a `color`.
## Generates all legal rook moves in a `game` starting from `field` for a
## `color`.
if game.board[field] != WRook * ord(color):
return @[]
var res = newSeq[Move]()
@ -602,7 +636,8 @@ proc genLegalRookMoves(game: Game, field: int, color: Color): seq[Move] =
return res
proc genLegalQueenMoves(game: Game, field: int, color: Color): seq[Move] =
## Generates all legal queen moves starting from `field` in a `game` for a `color`.
## Generates all legal queen moves in a `game` starting from `field` for a
## `color`.
if game.board[field] != WQueen * ord(color):
return @[]
var res = newSeq[Move]()
@ -613,7 +648,8 @@ proc genLegalQueenMoves(game: Game, field: int, color: Color): seq[Move] =
return res
proc genLegalKingMoves(game: Game, field: int, color: Color): seq[Move] =
## Generates all legal king moves starting from `field` in a `game` for a `color`.
## Generates all legal king moves in a `game` starting from `field` for a
## `color`.
if game.board[field] != WKing * ord(color):
return @[]
var res = newSeq[Move]()
@ -638,7 +674,8 @@ proc genPawnPromotion(move: Move, color: Color): seq[Move] =
return promotions
proc genLegalPawnMoves(game: Game, field: int, color: Color): seq[Move] =
## Generates all legal pawn moves starting from `field` in a `game` for a `color`.
## 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]()
@ -653,7 +690,7 @@ proc genLegalPawnMoves(game: Game, field: int, color: Color): seq[Move] =
return res
proc genLegalMoves*(game: Game, field: int, color: Color): seq[Move] =
## Generates all legal moves starting from `field` in a `game` for a `color`.
## Generates all legal moves in a `game` starting from `field` for a `color`.
var legal_moves = newSeq[Move]()
var target = ord(color) * game.board[field]
if 0 < target and target < WEnPassant:
@ -683,9 +720,11 @@ proc genLegalMoves*(game: Game, color: Color): seq[Move] =
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`.
## Tries to castle in a given `game` with the king of a given `color` from
## `kstart`.
## `dest_kingside` for kingside castling, else castling is queenside.
## This process checks for the legality of the move and performs the switch of `game.to_move`
## This process checks for the legality of the move and performs the switch
## of `game.to_move`
if game.toMove != color:
return false
var kdest = kstart
@ -717,12 +756,10 @@ proc castling(game: var Game, kstart: int, dest_kingside: bool,
return true
return false
proc getPrevBoard*(game: Game): seq[Board] =
return game.previousBoard
proc checkedMove*(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`
## Tries to make a `move` in a given `game``.
## This process checks for the legality of the move and performs the switch
## of `game.to_move` with exception of castling (castling() switches).
let start = move.start
let dest = move.dest
let color = move.color
@ -769,15 +806,16 @@ proc checkedMove*(game: var Game, move: Move): bool {.discardable.} =
return true
proc hasNoMoves(game: Game, color: Color): bool =
## Checks if a player of a given `color` has no legal moves in a `game`.
## Returns true if the `color` player has no legal moves in a `game`.
return (game.genLegalMoves(color) == @[])
proc isCheckmate*(game: Game, color: Color): bool =
## Checks if a player of a given `color` in a `game` is checkmate.
## Returns true if the `color` player is checkmate in a `game`.
return game.hasNoMoves(color) and game.isInCheck(color)
proc threeMoveRep(game: Game): bool =
## Checks if a `rep`-times repitition happened on the last move of the `game`.
## Returns true if a 3-fold repitition happened on the last move of the
## `game`.
var lastState = game.previousBoard[game.previousBoard.high]
var lastCastleRights = game.previousCastleRights[game.previousBoard.high]
var reps = 0
@ -788,14 +826,14 @@ proc threeMoveRep(game: Game): bool =
return reps >= 3
proc fiftyMoveRule(game: Game): bool =
## Checks if a draw with the fifty move rule is available in a `game`.
## Returns true if a draw can be claimed by the 50 move rule in a `game`.
return game.fiftyMoveCounter >= 100
proc isDrawClaimable*(game: Game): bool =
## Checks if a draw is claimable by either player.
## Returns true if a draw is claimable by either player.
return game.threeMoveRep() or game.fiftyMoveRule()
proc isStalemate*(game: Game, color: Color): bool =
## Checks if a player of a given `color` in a `game` is stalemate.
## Returns true if the `color` player is stalemate in a `game`.
return (game.hasNoMoves(color) and not game.isInCheck(color)) or
game.board.checkInsufficientMaterial()

+ 2
- 1
game.nim
View File

@ -3,7 +3,8 @@ import rdstdin
import ./chess
proc runGame(): void =
proc runGame*(): void =
## Initializes and runs a game of chess.
var game = initGame()
var draw: string
game.echoBoard(game.toMove)

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