return V.HasFlags;
}
- // Some variants don't have en-passant
+ // Pawns specifications
+ static get PawnSpecs() {
+ return {
+ directions: { 'w': -1, 'b': 1 },
+ twoSquares: true,
+ promotions: [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN],
+ canCapture: true,
+ captureBackward: false,
+ bidirectional: false
+ };
+ }
+
+ // En-passant captures need a stack of squares:
static get HasEnpassant() {
return true;
}
return moves;
}
+ // Special case of en-passant captures: treated separately
+ getEnpassantCaptures([x, y], shiftX) {
+ const Lep = this.epSquares.length;
+ const epSquare = this.epSquares[Lep - 1]; //always at least one element
+ let enpassantMove = null;
+ if (
+ !!epSquare &&
+ epSquare.x == x + shiftX &&
+ Math.abs(epSquare.y - y) == 1
+ ) {
+ enpassantMove = this.getBasicMove([x, y], [epSquare.x, epSquare.y]);
+ enpassantMove.vanish.push({
+ x: x,
+ y: epSquare.y,
+ p: "p",
+ c: this.getColor(x, epSquare.y)
+ });
+ }
+ return !!enpassantMove ? [enpassantMove] : [];
+ }
+
// What are the pawn moves from square x,y ?
- getPotentialPawnMoves([x, y]) {
+ getPotentialPawnMoves([x, y], promotions) {
const color = this.turn;
- let moves = [];
const [sizeX, sizeY] = [V.size.x, V.size.y];
- const shiftX = color == "w" ? -1 : 1;
+ const pawnShiftX = V.PawnSpecs.directions[color];
const firstRank = color == "w" ? sizeX - 1 : 0;
const startRank = color == "w" ? sizeX - 2 : 1;
const lastRank = color == "w" ? 0 : sizeX - 1;
- // NOTE: next condition is generally true (no pawn on last rank)
- if (x + shiftX >= 0 && x + shiftX < sizeX) {
- const finalPieces =
- x + shiftX == lastRank
- ? [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN]
- : [V.PAWN];
- if (this.board[x + shiftX][y] == V.EMPTY) {
- // One square forward
- for (let piece of finalPieces) {
- moves.push(
- this.getBasicMove([x, y], [x + shiftX, y], {
- c: color,
- p: piece
- })
- );
- }
- // Next condition because pawns on 1st rank can generally jump
- if (
- [startRank, firstRank].includes(x) &&
- this.board[x + 2 * shiftX][y] == V.EMPTY
- ) {
- // Two squares jump
- moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y]));
- }
+ // Consider all potential promotions:
+ const addMoves = ([x1, y1], [x2, y2], moves) => {
+ let finalPieces = [V.PAWN];
+ if (x2 == lastRank) {
+ // promotions arg: special override for Hiddenqueen variant
+ if (!!promotions) finalPieces = promotions;
+ else if (!!V.PawnSpecs.promotions)
+ finalPieces = V.PawnSpecs.promotions;
}
- // Captures
- for (let shiftY of [-1, 1]) {
- if (
- y + shiftY >= 0 &&
- y + shiftY < sizeY &&
- this.board[x + shiftX][y + shiftY] != V.EMPTY &&
- this.canTake([x, y], [x + shiftX, y + shiftY])
- ) {
- for (let piece of finalPieces) {
- moves.push(
- this.getBasicMove([x, y], [x + shiftX, y + shiftY], {
- c: color,
- p: piece
- })
- );
+ for (let piece of finalPieces) {
+ moves.push(
+ this.getBasicMove([x1, y1], [x2, y2], {
+ c: color,
+ p: piece
+ })
+ );
+ }
+ }
+
+ // Pawn movements in shiftX direction:
+ const getPawnMoves = (shiftX) => {
+ let moves = [];
+ // NOTE: next condition is generally true (no pawn on last rank)
+ if (x + shiftX >= 0 && x + shiftX < sizeX) {
+ if (this.board[x + shiftX][y] == V.EMPTY) {
+ // One square forward
+ addMoves([x, y], [x + shiftX, y], moves);
+ // Next condition because pawns on 1st rank can generally jump
+ if (
+ V.PawnSpecs.twoSquares &&
+ [startRank, firstRank].includes(x) &&
+ this.board[x + 2 * shiftX][y] == V.EMPTY
+ ) {
+ // Two squares jump
+ moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y]));
+ }
+ }
+ // Captures
+ if (V.PawnSpecs.canCapture) {
+ for (let shiftY of [-1, 1]) {
+ if (
+ y + shiftY >= 0 &&
+ y + shiftY < sizeY
+ ) {
+ if (
+ this.board[x + shiftX][y + shiftY] != V.EMPTY &&
+ this.canTake([x, y], [x + shiftX, y + shiftY])
+ ) {
+ addMoves([x, y], [x + shiftX, y + shiftY], moves);
+ }
+ if (
+ V.PawnSpecs.captureBackward &&
+ x - shiftX >= 0 && x - shiftX < V.size.x &&
+ this.board[x - shiftX][y + shiftY] != V.EMPTY &&
+ this.canTake([x, y], [x - shiftX, y + shiftY])
+ ) {
+ addMoves([x, y], [x + shiftX, y + shiftY], moves);
+ }
+ }
}
}
}
+ return moves;
}
+ let pMoves = getPawnMoves(pawnShiftX);
+ if (V.PawnSpecs.bidirectional)
+ pMoves = pMoves.concat(getPawnMoves(-pawnShiftX));
+
if (V.HasEnpassant) {
- // En passant
- const Lep = this.epSquares.length;
- const epSquare = this.epSquares[Lep - 1]; //always at least one element
- if (
- !!epSquare &&
- epSquare.x == x + shiftX &&
- Math.abs(epSquare.y - y) == 1
- ) {
- let enpassantMove = this.getBasicMove([x, y], [epSquare.x, epSquare.y]);
- enpassantMove.vanish.push({
- x: x,
- y: epSquare.y,
- p: "p",
- c: this.getColor(x, epSquare.y)
- });
- moves.push(enpassantMove);
- }
+ // NOTE: backward en-passant captures are not considered
+ // because no rules define them (for now).
+ Array.prototype.push.apply(
+ pMoves,
+ this.getEnpassantCaptures([x, y], pawnShiftX)
+ );
}
- return moves;
+ return pMoves;
}
// What are the rook moves from square x,y ?
if (this.castleFlags[c][castleSide] >= V.size.y) continue;
// If this code is reached, rooks and king are on initial position
+ const rookPos = this.castleFlags[c][castleSide];
+ if (this.getColor(x, rookPos) != c)
+ // Rook is here but changed color (see Benedict)
+ continue;
+
// Nothing on the path of the king ? (and no checks)
const finDist = finalSquares[castleSide][0] - y;
let step = finDist / Math.max(1, Math.abs(finDist));
// Nothing on the path to the rook?
step = castleSide == 0 ? -1 : 1;
- const rookPos = this.castleFlags[c][castleSide];
for (i = y + step; i != rookPos; i += step) {
if (this.board[x][i] != V.EMPTY) continue castlingCheck;
}
projects / vchess.git / blobdiff