| 1 | class BerolinaRules extends ChessRules |
| 2 | { |
| 3 | // En-passant after 2-sq jump |
| 4 | getEpSquare(moveOrSquare) |
| 5 | { |
| 6 | if (!moveOrSquare) |
| 7 | return undefined; |
| 8 | if (typeof moveOrSquare === "string") |
| 9 | { |
| 10 | const square = moveOrSquare; |
| 11 | if (square == "-") |
| 12 | return undefined; |
| 13 | return V.SquareToCoords(square); |
| 14 | } |
| 15 | // Argument is a move: |
| 16 | const move = moveOrSquare; |
| 17 | const [sx,ex,sy] = [move.start.x,move.end.x,move.start.y]; |
| 18 | if (this.getPiece(sx,sy) == V.PAWN && Math.abs(sx - ex) == 2) |
| 19 | { |
| 20 | return { |
| 21 | x: ex, |
| 22 | y: (move.end.y + sy)/2 |
| 23 | }; |
| 24 | } |
| 25 | return undefined; //default |
| 26 | } |
| 27 | |
| 28 | // Special pawn rules: promotions to captured friendly pieces, |
| 29 | // optional on ranks 8-9 and mandatory on rank 10. |
| 30 | getPotentialPawnMoves([x,y]) |
| 31 | { |
| 32 | const color = this.turn; |
| 33 | let moves = []; |
| 34 | const [sizeX,sizeY] = [V.size.x,V.size.y]; |
| 35 | const shiftX = (color == "w" ? -1 : 1); |
| 36 | const firstRank = (color == 'w' ? sizeX-1 : 0); |
| 37 | const startRank = (color == "w" ? sizeX-2 : 1); |
| 38 | const lastRank = (color == "w" ? 0 : sizeX-1); |
| 39 | |
| 40 | if (x+shiftX >= 0 && x+shiftX < sizeX) //TODO: always true |
| 41 | { |
| 42 | const finalPieces = x + shiftX == lastRank |
| 43 | ? [V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN] |
| 44 | : [V.PAWN] |
| 45 | // One square diagonally |
| 46 | for (let shiftY of [-1,1]) |
| 47 | { |
| 48 | if (this.board[x+shiftX][y+shiftY] == V.EMPTY) |
| 49 | { |
| 50 | for (let piece of finalPieces) |
| 51 | { |
| 52 | moves.push(this.getBasicMove([x,y], [x+shiftX,y+shiftY], |
| 53 | {c:pawnColor,p:piece})); |
| 54 | } |
| 55 | if (x == startRank && this.board[x+2*shiftX][y] == V.EMPTY) |
| 56 | { |
| 57 | // Two squares jump |
| 58 | moves.push(this.getBasicMove([x,y], [x+2*shiftX,y+2*shiftY]); |
| 59 | } |
| 60 | } |
| 61 | } |
| 62 | // Capture |
| 63 | if (this.board[x+shiftX][y] != V.EMPTY |
| 64 | && this.canTake([x,y], [x+shiftX,y])) |
| 65 | { |
| 66 | for (let piece of finalPieces) |
| 67 | { |
| 68 | moves.push(this.getBasicMove([x,y], [x+shiftX,y+shiftY], |
| 69 | {c:pawnColor,p:piece})); |
| 70 | } |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | // En passant |
| 75 | const Lep = this.epSquares.length; |
| 76 | const epSquare = this.epSquares[Lep-1]; //always at least one element |
| 77 | if (!!epSquare && epSquare.x == x+shiftX && epSquare.y == y) |
| 78 | { |
| 79 | let enpassantMove = this.getBasicMove([x,y], [x+shift,y]); |
| 80 | enpassantMove.vanish.push({ |
| 81 | x: epSquare.x, |
| 82 | y: y, |
| 83 | p: 'p', |
| 84 | c: this.getColor(epSquare.x,y) |
| 85 | }); |
| 86 | moves.push(enpassantMove); |
| 87 | } |
| 88 | |
| 89 | return moves; |
| 90 | } |
| 91 | } |
| 92 | |
| 93 | const VariantRules = BerolinaRules; |