+ getEnpassantCaptures([x, y], shift) {
+ const Lep = this.epSquares.length;
+ const epSquare = this.epSquares[Lep - 1]; //always at least one element
+ if (
+ !!epSquare &&
+ epSquare[0].x == x + shift &&
+ epSquare[0].y == y
+ ) {
+ let enpassantMove = this.getBasicMove([x, y], [x + shift, y]);
+ enpassantMove.vanish.push({
+ x: x,
+ y: epSquare[1],
+ p: "p",
+ c: this.getColor(x, epSquare[1])
+ });
+ return [enpassantMove];
+ }
+ return [];
+ }
+
+ // Special pawns movements
+ getPotentialPawnMoves([x, y]) {
+ const color = this.turn;
+ 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
+ ? [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN]
+ : [V.PAWN];
+
+ // One square diagonally
+ for (let shiftY of [-1, 1]) {
+ if (this.board[x + shiftX][y + shiftY] == V.EMPTY) {
+ for (let piece of finalPieces) {
+ moves.push(
+ this.getBasicMove([x, y], [x + shiftX, y + shiftY], {
+ c: color,
+ p: piece
+ })
+ );
+ }
+ if (
+ V.PawnSpecs.twoSquares &&
+ x == startRank &&
+ y + 2 * shiftY >= 0 &&
+ y + 2 * shiftY < sizeY &&
+ this.board[x + 2 * shiftX][y + 2 * shiftY] == V.EMPTY
+ ) {
+ // Two squares jump
+ moves.push(
+ this.getBasicMove([x, y], [x + 2 * shiftX, y + 2 * shiftY])
+ );
+ }
+ }
+ }
+ // Capture
+ if (
+ this.board[x + shiftX][y] != V.EMPTY &&
+ this.canTake([x, y], [x + shiftX, y])
+ ) {
+ for (let piece of finalPieces) {
+ moves.push(
+ this.getBasicMove([x, y], [x + shiftX, y], { c: color, p: piece })
+ );
+ }
+ }
+
+ // Next condition so that other variants could inherit from this class
+ if (V.HasEnpassant) {
+ // NOTE: backward en-passant captures are not considered
+ // because no rules define them (for now).
+ Array.prototype.push.apply(
+ moves,
+ this.getEnpassantCaptures([x, y], shiftX)
+ );
+ }
+
+ return moves;
+ }
+
+ isAttackedByPawn([x, y], color) {
+ let pawnShift = (color == "w" ? 1 : -1);
+ return (
+ x + pawnShift >= 0 && x + pawnShift < V.size.x &&
+ this.getPiece(x + pawnShift, y) == V.PAWN &&
+ this.getColor(x + pawnShift, y) == color
+ );
+ }
+
+ static get SEARCH_DEPTH() {
+ return 2;
+ }
+
+ getNotation(move) {
+ const piece = this.getPiece(move.start.x, move.start.y);
+ if (piece == V.PAWN) {
+ // Pawn move
+ const finalSquare = V.CoordsToSquare(move.end);
+ let notation = "";
+ if (move.vanish.length == 2)
+ // Capture
+ notation = "Px" + finalSquare;
+ else {
+ // No capture: indicate the initial square for potential ambiguity
+ const startSquare = V.CoordsToSquare(move.start);
+ notation = startSquare + finalSquare;
+ }
+ if (move.appear[0].p != V.PAWN)
+ // Promotion
+ notation += "=" + move.appear[0].p.toUpperCase();
+ return notation;
+ }
+ return super.getNotation(move); //all other pieces are orthodox
+ }
+
+};