- // TODO: find a more general way to describe pawn movements to avoid
- // re-writing almost the same function for several variants.
- getPotentialPawnMoves([x, y]) {
- const color = this.turn;
- const piece = this.getPiece(x, y);
- let moves = [];
- const [sizeX, sizeY] = [V.size.x, V.size.y];
- const shiftX = color == "w" ? -1 : 1;
- const startRank = color == "w" ? sizeX - 2 : 1;
- const lastRank = color == "w" ? 0 : sizeX - 1;
-
- const finalPieces =
- x + shiftX == lastRank
- ? piece == V.PAWN
- ? [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN]
- : [V.QUEEN] //hidden queen revealed
- : piece;
- if (this.board[x + shiftX][y] == V.EMPTY) {
- // One square forward
- for (let p of finalPieces) {
- moves.push(
- this.getBasicMove([x, y], [x + shiftX, y], {
- c: color,
- p: p
- })
- );
- }
- if (
- x == startRank &&
- this.board[x + 2 * shiftX][y] == V.EMPTY
- ) {
- // Two squares jump
- moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y]));
- }
- }
- // 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 p of finalPieces) {
- moves.push(
- this.getBasicMove([x, y], [x + shiftX, y + shiftY], {
- c: color,
- p: p
- })
- );
- }
- }
- }
-
- 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);
- }
+ getEnpassantCaptures([x, y], shiftX) {
+ const Lep = this.epSquares.length;
+ const epSquare = this.epSquares[Lep - 1];
+ 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,
+ // Captured piece may be a hidden queen
+ p: this.board[x][epSquare.y][1],
+ c: this.getColor(x, epSquare.y)
+ });