if (position.length == 0) return false;
const rows = position.split("/");
if (rows.length != V.size.x) return false;
- let kings = {};
+ let kings = { "k": 0, "K": 0 };
for (let row of rows) {
let sumElts = 0;
for (let i = 0; i < row.length; i++) {
- if (['K','k'].includes(row[i]))
- kings[row[i]] = true;
+ if (['K','k'].includes(row[i])) kings[row[i]]++;
if (V.PIECES.includes(row[i].toLowerCase())) sumElts++;
else {
const num = parseInt(row[i]);
}
if (sumElts != V.size.y) return false;
}
- // Both kings should be on board:
- if (Object.keys(kings).length != 2)
- return false;
+ // Both kings should be on board. Exactly one per color.
+ if (Object.values(kings).some(v => v != 1)) return false;
return true;
}
return V.CoordToColumn(coords.y) + (V.size.x - coords.x);
}
- // Path to pieces
+ // Path to pieces (standard ones in pieces/ folder)
getPpath(b) {
- return b; //usual pieces in pieces/ folder
+ return b;
}
// Path to promotion pieces (usually the same)
// Position part of the FEN string
getBaseFen() {
+ const format = (count) => {
+ // if more than 9 consecutive free spaces, break the integer,
+ // otherwise FEN parsing will fail.
+ if (count <= 9) return count;
+ // Currently only boards of size up to 11 or 12:
+ return "9" + (count - 9);
+ };
let position = "";
for (let i = 0; i < V.size.x; i++) {
let emptyCount = 0;
else {
if (emptyCount > 0) {
// Add empty squares in-between
- position += emptyCount;
+ position += format(emptyCount);
emptyCount = 0;
}
position += V.board2fen(this.board[i][j]);
}
if (emptyCount > 0) {
// "Flush remainder"
- position += emptyCount;
+ position += format(emptyCount);
}
if (i < V.size.x - 1) position += "/"; //separate rows
}
// Extract (relevant) flags from fen
setFlags(fenflags) {
// white a-castle, h-castle, black a-castle, h-castle
- this.castleFlags = { w: [true, true], b: [true, true] };
+ this.castleFlags = { w: [-1, -1], b: [-1, -1] };
for (let i = 0; i < 4; i++) {
this.castleFlags[i < 2 ? "w" : "b"][i % 2] =
V.ColumnToCoord(fenflags.charAt(i));
// Build a regular move from its initial and destination squares.
// tr: transformation
getBasicMove([sx, sy], [ex, ey], tr) {
+ const initColor = this.getColor(sx, sy);
+ const initPiece = this.getPiece(sx, sy);
let mv = new Move({
appear: [
new PiPo({
x: ex,
y: ey,
- c: tr ? tr.c : this.getColor(sx, sy),
- p: tr ? tr.p : this.getPiece(sx, sy)
+ c: tr ? tr.c : initColor,
+ p: tr ? tr.p : initPiece
})
],
vanish: [
new PiPo({
x: sx,
y: sy,
- c: this.getColor(sx, sy),
- p: this.getPiece(sx, sy)
+ c: initColor,
+ p: initPiece
})
]
});
enpassantMove.vanish.push({
x: x,
y: epSquare.y,
- p: "p",
+ // Captured piece is usually a pawn, but next line seems harmless
+ p: this.getPiece(x, epSquare.y),
c: this.getColor(x, epSquare.y)
});
}
return !!enpassantMove ? [enpassantMove] : [];
}
+ // Consider all potential promotions:
+ addPawnMoves([x1, y1], [x2, y2], moves, promotions) {
+ let finalPieces = [V.PAWN];
+ const color = this.turn;
+ const lastRank = (color == "w" ? 0 : V.size.x - 1);
+ if (x2 == lastRank) {
+ // promotions arg: special override for Hiddenqueen variant
+ if (!!promotions) finalPieces = promotions;
+ else if (!!V.PawnSpecs.promotions)
+ finalPieces = V.PawnSpecs.promotions;
+ }
+ let tr = null;
+ for (let piece of finalPieces) {
+ tr = (piece != V.PAWN ? { c: color, p: piece } : null);
+ moves.push(this.getBasicMove([x1, y1], [x2, y2], tr));
+ }
+ }
+
// What are the pawn moves from square x,y ?
getPotentialPawnMoves([x, y], promotions) {
const color = this.turn;
const [sizeX, sizeY] = [V.size.x, V.size.y];
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;
-
- // 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;
- }
- for (let piece of finalPieces) {
- moves.push(
- this.getBasicMove([x1, y1], [x2, y2], {
- c: color,
- p: piece
- })
- );
- }
- }
+ const firstRank = (color == "w" ? sizeX - 1 : 0);
+ const startRank = (color == "w" ? sizeX - 2 : 1);
// Pawn movements in shiftX direction:
const getPawnMoves = (shiftX) => {
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);
+ this.addPawnMoves([x, y], [x + shiftX, y], moves, promotions);
// Next condition because pawns on 1st rank can generally jump
if (
V.PawnSpecs.twoSquares &&
this.board[x + shiftX][y + shiftY] != V.EMPTY &&
this.canTake([x, y], [x + shiftX, y + shiftY])
) {
- addMoves([x, y], [x + shiftX, y + shiftY], moves);
+ this.addPawnMoves(
+ [x, y], [x + shiftX, y + shiftY],
+ moves, promotions
+ );
}
if (
V.PawnSpecs.captureBackward &&
this.board[x - shiftX][y + shiftY] != V.EMPTY &&
this.canTake([x, y], [x - shiftX, y + shiftY])
) {
- addMoves([x, y], [x + shiftX, y + shiftY], moves);
+ this.addPawnMoves(
+ [x, y], [x + shiftX, y + shiftY],
+ moves, promotions
+ );
}
}
}
return moves;
}
- getCastleMoves([x, y]) {
+ // "castleInCheck" arg to let some variants castle under check
+ getCastleMoves([x, y], castleInCheck) {
const c = this.getColor(x, y);
if (x != (c == "w" ? V.size.x - 1 : 0) || y != this.INIT_COL_KING[c])
return []; //x isn't first rank, or king has moved (shortcut)
castleSide++ //large, then small
) {
if (this.castleFlags[c][castleSide] >= V.size.y) continue;
- // If this code is reached, rooks and king are on initial position
+ // If this code is reached, rook and king are on initial position
+ // NOTE: in some variants this is not a rook, but let's keep variable name
const rookPos = this.castleFlags[c][castleSide];
+ const castlingPiece = this.getPiece(x, rookPos);
if (this.getColor(x, rookPos) != c)
// Rook is here but changed color (see Benedict)
continue;
i = y;
do {
if (
- this.isAttacked([x, i], oppCol) ||
+ (!castleInCheck && this.isAttacked([x, i], oppCol)) ||
(this.board[x][i] != V.EMPTY &&
// NOTE: next check is enough, because of chessboard constraints
(this.getColor(x, i) != c ||
- ![V.KING, V.ROOK].includes(this.getPiece(x, i))))
+ ![V.KING, castlingPiece].includes(this.getPiece(x, i))))
) {
continue castlingCheck;
}
new Move({
appear: [
new PiPo({ x: x, y: finalSquares[castleSide][0], p: V.KING, c: c }),
- new PiPo({ x: x, y: finalSquares[castleSide][1], p: V.ROOK, c: c })
+ new PiPo({ x: x, y: finalSquares[castleSide][1], p: castlingPiece, c: c })
],
vanish: [
new PiPo({ x: x, y: y, p: V.KING, c: c }),
- new PiPo({ x: x, y: rookPos, p: V.ROOK, c: c })
+ new PiPo({ x: x, y: rookPos, p: castlingPiece, c: c })
],
end:
Math.abs(y - rookPos) <= 2
// Is color under check after his move ?
underCheck(color) {
- return this.isAttacked(this.kingPos[color], [V.GetOppCol(color)]);
+ return this.isAttacked(this.kingPos[color], V.GetOppCol(color));
}
/////////////////
play(move) {
// DEBUG:
// if (!this.states) this.states = [];
-// const stateFen = this.getBaseFen() + this.getTurnFen();// + this.getFlagsFen();
+// const stateFen = this.getFen() + JSON.stringify(this.kingPos);
// this.states.push(stateFen);
this.prePlay(move);
this.postPlay(move);
}
+ updateCastleFlags(move, piece) {
+ const c = V.GetOppCol(this.turn);
+ const firstRank = (c == "w" ? V.size.x - 1 : 0);
+ // Update castling flags if rooks are moved
+ const oppCol = V.GetOppCol(c);
+ const oppFirstRank = V.size.x - 1 - firstRank;
+ if (piece == V.KING && move.appear.length > 0)
+ this.castleFlags[c] = [V.size.y, V.size.y];
+ else if (
+ move.start.x == firstRank && //our rook moves?
+ this.castleFlags[c].includes(move.start.y)
+ ) {
+ const flagIdx = (move.start.y == this.castleFlags[c][0] ? 0 : 1);
+ this.castleFlags[c][flagIdx] = V.size.y;
+ }
+ // NOTE: not "else if" because a rook could take an opposing rook
+ if (
+ move.end.x == oppFirstRank && //we took opponent rook?
+ this.castleFlags[oppCol].includes(move.end.y)
+ ) {
+ const flagIdx = (move.end.y == this.castleFlags[oppCol][0] ? 0 : 1);
+ this.castleFlags[oppCol][flagIdx] = V.size.y;
+ }
+ }
+
// After move is played, update variables + flags
postPlay(move) {
const c = V.GetOppCol(this.turn);
else
// Crazyhouse-like variants
piece = move.appear[0].p;
- const firstRank = c == "w" ? V.size.x - 1 : 0;
// Update king position + flags
if (piece == V.KING && move.appear.length > 0) {
this.kingPos[c][0] = move.appear[0].x;
this.kingPos[c][1] = move.appear[0].y;
- if (V.HasCastle) this.castleFlags[c] = [V.size.y, V.size.y];
return;
}
- if (V.HasCastle) {
- // Update castling flags if rooks are moved
- const oppCol = V.GetOppCol(c);
- const oppFirstRank = V.size.x - 1 - firstRank;
- if (
- move.start.x == firstRank && //our rook moves?
- this.castleFlags[c].includes(move.start.y)
- ) {
- const flagIdx = (move.start.y == this.castleFlags[c][0] ? 0 : 1);
- this.castleFlags[c][flagIdx] = V.size.y;
- } else if (
- move.end.x == oppFirstRank && //we took opponent rook?
- this.castleFlags[oppCol].includes(move.end.y)
- ) {
- const flagIdx = (move.end.y == this.castleFlags[oppCol][0] ? 0 : 1);
- this.castleFlags[oppCol][flagIdx] = V.size.y;
- }
- }
+ if (V.HasCastle) this.updateCastleFlags(move, piece);
}
preUndo() {}
this.postUndo(move);
// DEBUG:
-// const stateFen = this.getBaseFen() + this.getTurnFen();// + this.getFlagsFen();
+// const stateFen = this.getFen() + JSON.stringify(this.kingPos);
// if (stateFen != this.states[this.states.length-1]) debugger;
// this.states.pop();
}
// What is the score ? (Interesting if game is over)
getCurrentScore() {
- if (this.atLeastOneMove())
- return "*";
-
+ if (this.atLeastOneMove()) return "*";
// Game over
const color = this.turn;
// No valid move: stalemate or checkmate?
- if (!this.isAttacked(this.kingPos[color], V.GetOppCol(color)))
- return "1/2";
+ if (!this.underCheck(color)) return "1/2";
// OK, checkmate
return (color == "w" ? "0-1" : "1-0");
}
return V.INFINITY;
}
- // Search depth: 2 for high branching factor, 4 for small (Loser chess, eg.)
+ // Search depth: 1,2 for high branching factor, 4 for small (Loser chess, eg.)
static get SEARCH_DEPTH() {
return 3;
}