A bit more flexibility in boards drawing
[vchess.git] / client / src / base_rules.js
1 // (Orthodox) Chess rules are defined in ChessRules class.
2 // Variants generally inherit from it, and modify some parts.
3
4 import { ArrayFun } from "@/utils/array";
5 import { randInt, shuffle } from "@/utils/alea";
6
7 // class "PiPo": Piece + Position
8 export const PiPo = class PiPo {
9 // o: {piece[p], color[c], posX[x], posY[y]}
10 constructor(o) {
11 this.p = o.p;
12 this.c = o.c;
13 this.x = o.x;
14 this.y = o.y;
15 }
16 };
17
18 export const Move = class Move {
19 // o: {appear, vanish, [start,] [end,]}
20 // appear,vanish = arrays of PiPo
21 // start,end = coordinates to apply to trigger move visually (think castle)
22 constructor(o) {
23 this.appear = o.appear;
24 this.vanish = o.vanish;
25 this.start = o.start ? o.start : { x: o.vanish[0].x, y: o.vanish[0].y };
26 this.end = o.end ? o.end : { x: o.appear[0].x, y: o.appear[0].y };
27 }
28 };
29
30 // NOTE: x coords = top to bottom; y = left to right
31 // (from white player perspective)
32 export const ChessRules = class ChessRules {
33
34 //////////////
35 // MISC UTILS
36
37 // Some variants don't have flags:
38 static get HasFlags() {
39 return true;
40 }
41
42 // Or castle
43 static get HasCastle() {
44 return V.HasFlags;
45 }
46
47 // Pawns specifications
48 static get PawnSpecs() {
49 return {
50 directions: { 'w': -1, 'b': 1 },
51 initShift: { w: 1, b: 1 },
52 twoSquares: true,
53 threeSquares: false,
54 promotions: [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN],
55 canCapture: true,
56 captureBackward: false,
57 bidirectional: false
58 };
59 }
60
61 // En-passant captures need a stack of squares:
62 static get HasEnpassant() {
63 return true;
64 }
65
66 // Some variants cannot have analyse mode
67 static get CanAnalyze() {
68 return true;
69 }
70 // Patch: issues with javascript OOP, objects can't access static fields.
71 get canAnalyze() {
72 return V.CanAnalyze;
73 }
74
75 // Some variants show incomplete information,
76 // and thus show only a partial moves list or no list at all.
77 static get ShowMoves() {
78 return "all";
79 }
80 get showMoves() {
81 return V.ShowMoves;
82 }
83
84 // Sometimes moves must remain hidden until game ends
85 static get SomeHiddenMoves() {
86 return false;
87 }
88 get someHiddenMoves() {
89 return V.SomeHiddenMoves;
90 }
91
92 // Generally true, unless the variant includes random effects
93 static get CorrConfirm() {
94 return true;
95 }
96
97 // Used for Monochrome variant (TODO: harmonize: !canFlip ==> showFirstTurn)
98 get showFirstTurn() {
99 return false;
100 }
101
102 // Some variants always show the same orientation
103 static get CanFlip() {
104 return true;
105 }
106 get canFlip() {
107 return V.CanFlip;
108 }
109
110 // For (generally old) variants without checkered board
111 static get Monochrome() {
112 return false;
113 }
114
115 // Some games are drawn unusually (bottomr right corner is black)
116 static get DarkBottomRight() {
117 return false;
118 }
119
120 // Some variants require lines drawing
121 static get Lines() {
122 if (V.Monochrome) {
123 let lines = [];
124 // Draw all inter-squares lines
125 for (let i = 0; i <= V.size.x; i++)
126 lines.push([[i, 0], [i, V.size.y]]);
127 for (let j = 0; j <= V.size.y; j++)
128 lines.push([[0, j], [V.size.x, j]]);
129 return lines;
130 }
131 return null;
132 }
133
134 // In some variants, the player who repeat a position loses
135 static get LoseOnRepetition() {
136 return false;
137 }
138
139 // Some variants use click infos:
140 doClick() {
141 return null;
142 }
143
144 // Some variants may need to highlight squares on hover (Hamilton, Weiqi...)
145 hoverHighlight() {
146 return false;
147 }
148
149 static get IMAGE_EXTENSION() {
150 // All pieces should be in the SVG format
151 return ".svg";
152 }
153
154 // Turn "wb" into "B" (for FEN)
155 static board2fen(b) {
156 return b[0] == "w" ? b[1].toUpperCase() : b[1];
157 }
158
159 // Turn "p" into "bp" (for board)
160 static fen2board(f) {
161 return f.charCodeAt() <= 90 ? "w" + f.toLowerCase() : "b" + f;
162 }
163
164 // Check if FEN describes a board situation correctly
165 static IsGoodFen(fen) {
166 const fenParsed = V.ParseFen(fen);
167 // 1) Check position
168 if (!V.IsGoodPosition(fenParsed.position)) return false;
169 // 2) Check turn
170 if (!fenParsed.turn || !V.IsGoodTurn(fenParsed.turn)) return false;
171 // 3) Check moves count
172 if (!fenParsed.movesCount || !(parseInt(fenParsed.movesCount, 10) >= 0))
173 return false;
174 // 4) Check flags
175 if (V.HasFlags && (!fenParsed.flags || !V.IsGoodFlags(fenParsed.flags)))
176 return false;
177 // 5) Check enpassant
178 if (
179 V.HasEnpassant &&
180 (!fenParsed.enpassant || !V.IsGoodEnpassant(fenParsed.enpassant))
181 ) {
182 return false;
183 }
184 return true;
185 }
186
187 // Is position part of the FEN a priori correct?
188 static IsGoodPosition(position) {
189 if (position.length == 0) return false;
190 const rows = position.split("/");
191 if (rows.length != V.size.x) return false;
192 let kings = { "k": 0, "K": 0 };
193 for (let row of rows) {
194 let sumElts = 0;
195 for (let i = 0; i < row.length; i++) {
196 if (['K','k'].includes(row[i])) kings[row[i]]++;
197 if (V.PIECES.includes(row[i].toLowerCase())) sumElts++;
198 else {
199 const num = parseInt(row[i], 10);
200 if (isNaN(num)) return false;
201 sumElts += num;
202 }
203 }
204 if (sumElts != V.size.y) return false;
205 }
206 // Both kings should be on board. Exactly one per color.
207 if (Object.values(kings).some(v => v != 1)) return false;
208 return true;
209 }
210
211 // For FEN checking
212 static IsGoodTurn(turn) {
213 return ["w", "b"].includes(turn);
214 }
215
216 // For FEN checking
217 static IsGoodFlags(flags) {
218 // NOTE: a little too permissive to work with more variants
219 return !!flags.match(/^[a-z]{4,4}$/);
220 }
221
222 // NOTE: not with regexp to adapt to different board sizes. (TODO?)
223 static IsGoodEnpassant(enpassant) {
224 if (enpassant != "-") {
225 const ep = V.SquareToCoords(enpassant);
226 if (isNaN(ep.x) || !V.OnBoard(ep)) return false;
227 }
228 return true;
229 }
230
231 // 3 --> d (column number to letter)
232 static CoordToColumn(colnum) {
233 return String.fromCharCode(97 + colnum);
234 }
235
236 // d --> 3 (column letter to number)
237 static ColumnToCoord(column) {
238 return column.charCodeAt(0) - 97;
239 }
240
241 // a4 --> {x:3,y:0}
242 static SquareToCoords(sq) {
243 return {
244 // NOTE: column is always one char => max 26 columns
245 // row is counted from black side => subtraction
246 x: V.size.x - parseInt(sq.substr(1), 10),
247 y: sq[0].charCodeAt() - 97
248 };
249 }
250
251 // {x:0,y:4} --> e8
252 static CoordsToSquare(coords) {
253 return V.CoordToColumn(coords.y) + (V.size.x - coords.x);
254 }
255
256 // Path to pieces (standard ones in pieces/ folder)
257 getPpath(b) {
258 return b;
259 }
260
261 // Path to promotion pieces (usually the same)
262 getPPpath(m) {
263 return this.getPpath(m.appear[0].c + m.appear[0].p);
264 }
265
266 // Aggregates flags into one object
267 aggregateFlags() {
268 return this.castleFlags;
269 }
270
271 // Reverse operation
272 disaggregateFlags(flags) {
273 this.castleFlags = flags;
274 }
275
276 // En-passant square, if any
277 getEpSquare(moveOrSquare) {
278 if (!moveOrSquare) return undefined;
279 if (typeof moveOrSquare === "string") {
280 const square = moveOrSquare;
281 if (square == "-") return undefined;
282 return V.SquareToCoords(square);
283 }
284 // Argument is a move:
285 const move = moveOrSquare;
286 const s = move.start,
287 e = move.end;
288 if (
289 s.y == e.y &&
290 Math.abs(s.x - e.x) == 2 &&
291 // Next conditions for variants like Atomic or Rifle, Recycle...
292 (move.appear.length > 0 && move.appear[0].p == V.PAWN) &&
293 (move.vanish.length > 0 && move.vanish[0].p == V.PAWN)
294 ) {
295 return {
296 x: (s.x + e.x) / 2,
297 y: s.y
298 };
299 }
300 return undefined; //default
301 }
302
303 // Can thing on square1 take thing on square2
304 canTake([x1, y1], [x2, y2]) {
305 return this.getColor(x1, y1) !== this.getColor(x2, y2);
306 }
307
308 // Is (x,y) on the chessboard?
309 static OnBoard(x, y) {
310 return x >= 0 && x < V.size.x && y >= 0 && y < V.size.y;
311 }
312
313 // Used in interface: 'side' arg == player color
314 canIplay(side, [x, y]) {
315 return this.turn == side && this.getColor(x, y) == side;
316 }
317
318 // On which squares is color under check ? (for interface)
319 getCheckSquares() {
320 const color = this.turn;
321 return (
322 this.underCheck(color)
323 // kingPos must be duplicated, because it may change:
324 ? [JSON.parse(JSON.stringify(this.kingPos[color]))]
325 : []
326 );
327 }
328
329 /////////////
330 // FEN UTILS
331
332 // Setup the initial random (asymmetric) position
333 static GenRandInitFen(randomness) {
334 if (randomness == 0)
335 // Deterministic:
336 return "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w 0 ahah -";
337
338 let pieces = { w: new Array(8), b: new Array(8) };
339 let flags = "";
340 // Shuffle pieces on first (and last rank if randomness == 2)
341 for (let c of ["w", "b"]) {
342 if (c == 'b' && randomness == 1) {
343 pieces['b'] = pieces['w'];
344 flags += flags;
345 break;
346 }
347
348 let positions = ArrayFun.range(8);
349
350 // Get random squares for bishops
351 let randIndex = 2 * randInt(4);
352 const bishop1Pos = positions[randIndex];
353 // The second bishop must be on a square of different color
354 let randIndex_tmp = 2 * randInt(4) + 1;
355 const bishop2Pos = positions[randIndex_tmp];
356 // Remove chosen squares
357 positions.splice(Math.max(randIndex, randIndex_tmp), 1);
358 positions.splice(Math.min(randIndex, randIndex_tmp), 1);
359
360 // Get random squares for knights
361 randIndex = randInt(6);
362 const knight1Pos = positions[randIndex];
363 positions.splice(randIndex, 1);
364 randIndex = randInt(5);
365 const knight2Pos = positions[randIndex];
366 positions.splice(randIndex, 1);
367
368 // Get random square for queen
369 randIndex = randInt(4);
370 const queenPos = positions[randIndex];
371 positions.splice(randIndex, 1);
372
373 // Rooks and king positions are now fixed,
374 // because of the ordering rook-king-rook
375 const rook1Pos = positions[0];
376 const kingPos = positions[1];
377 const rook2Pos = positions[2];
378
379 // Finally put the shuffled pieces in the board array
380 pieces[c][rook1Pos] = "r";
381 pieces[c][knight1Pos] = "n";
382 pieces[c][bishop1Pos] = "b";
383 pieces[c][queenPos] = "q";
384 pieces[c][kingPos] = "k";
385 pieces[c][bishop2Pos] = "b";
386 pieces[c][knight2Pos] = "n";
387 pieces[c][rook2Pos] = "r";
388 flags += V.CoordToColumn(rook1Pos) + V.CoordToColumn(rook2Pos);
389 }
390 // Add turn + flags + enpassant
391 return (
392 pieces["b"].join("") +
393 "/pppppppp/8/8/8/8/PPPPPPPP/" +
394 pieces["w"].join("").toUpperCase() +
395 " w 0 " + flags + " -"
396 );
397 }
398
399 // "Parse" FEN: just return untransformed string data
400 static ParseFen(fen) {
401 const fenParts = fen.split(" ");
402 let res = {
403 position: fenParts[0],
404 turn: fenParts[1],
405 movesCount: fenParts[2]
406 };
407 let nextIdx = 3;
408 if (V.HasFlags) Object.assign(res, { flags: fenParts[nextIdx++] });
409 if (V.HasEnpassant) Object.assign(res, { enpassant: fenParts[nextIdx] });
410 return res;
411 }
412
413 // Return current fen (game state)
414 getFen() {
415 return (
416 this.getBaseFen() + " " +
417 this.getTurnFen() + " " +
418 this.movesCount +
419 (V.HasFlags ? " " + this.getFlagsFen() : "") +
420 (V.HasEnpassant ? " " + this.getEnpassantFen() : "")
421 );
422 }
423
424 getFenForRepeat() {
425 // Omit movesCount, only variable allowed to differ
426 return (
427 this.getBaseFen() + "_" +
428 this.getTurnFen() +
429 (V.HasFlags ? "_" + this.getFlagsFen() : "") +
430 (V.HasEnpassant ? "_" + this.getEnpassantFen() : "")
431 );
432 }
433
434 // Position part of the FEN string
435 getBaseFen() {
436 const format = (count) => {
437 // if more than 9 consecutive free spaces, break the integer,
438 // otherwise FEN parsing will fail.
439 if (count <= 9) return count;
440 // Currently only boards of size up to 11 or 12:
441 return "9" + (count - 9);
442 };
443 let position = "";
444 for (let i = 0; i < V.size.x; i++) {
445 let emptyCount = 0;
446 for (let j = 0; j < V.size.y; j++) {
447 if (this.board[i][j] == V.EMPTY) emptyCount++;
448 else {
449 if (emptyCount > 0) {
450 // Add empty squares in-between
451 position += format(emptyCount);
452 emptyCount = 0;
453 }
454 position += V.board2fen(this.board[i][j]);
455 }
456 }
457 if (emptyCount > 0) {
458 // "Flush remainder"
459 position += format(emptyCount);
460 }
461 if (i < V.size.x - 1) position += "/"; //separate rows
462 }
463 return position;
464 }
465
466 getTurnFen() {
467 return this.turn;
468 }
469
470 // Flags part of the FEN string
471 getFlagsFen() {
472 let flags = "";
473 // Castling flags
474 for (let c of ["w", "b"])
475 flags += this.castleFlags[c].map(V.CoordToColumn).join("");
476 return flags;
477 }
478
479 // Enpassant part of the FEN string
480 getEnpassantFen() {
481 const L = this.epSquares.length;
482 if (!this.epSquares[L - 1]) return "-"; //no en-passant
483 return V.CoordsToSquare(this.epSquares[L - 1]);
484 }
485
486 // Turn position fen into double array ["wb","wp","bk",...]
487 static GetBoard(position) {
488 const rows = position.split("/");
489 let board = ArrayFun.init(V.size.x, V.size.y, "");
490 for (let i = 0; i < rows.length; i++) {
491 let j = 0;
492 for (let indexInRow = 0; indexInRow < rows[i].length; indexInRow++) {
493 const character = rows[i][indexInRow];
494 const num = parseInt(character, 10);
495 // If num is a number, just shift j:
496 if (!isNaN(num)) j += num;
497 // Else: something at position i,j
498 else board[i][j++] = V.fen2board(character);
499 }
500 }
501 return board;
502 }
503
504 // Extract (relevant) flags from fen
505 setFlags(fenflags) {
506 // white a-castle, h-castle, black a-castle, h-castle
507 this.castleFlags = { w: [-1, -1], b: [-1, -1] };
508 for (let i = 0; i < 4; i++) {
509 this.castleFlags[i < 2 ? "w" : "b"][i % 2] =
510 V.ColumnToCoord(fenflags.charAt(i));
511 }
512 }
513
514 //////////////////
515 // INITIALIZATION
516
517 // Fen string fully describes the game state
518 constructor(fen) {
519 if (!fen)
520 // In printDiagram() fen isn't supply because only getPpath() is used
521 // TODO: find a better solution!
522 return;
523 const fenParsed = V.ParseFen(fen);
524 this.board = V.GetBoard(fenParsed.position);
525 this.turn = fenParsed.turn;
526 this.movesCount = parseInt(fenParsed.movesCount, 10);
527 this.setOtherVariables(fen);
528 }
529
530 // Scan board for kings positions
531 scanKings(fen) {
532 // Squares of white and black king:
533 this.kingPos = { w: [-1, -1], b: [-1, -1] };
534 const fenRows = V.ParseFen(fen).position.split("/");
535 const startRow = { 'w': V.size.x - 1, 'b': 0 };
536 for (let i = 0; i < fenRows.length; i++) {
537 let k = 0; //column index on board
538 for (let j = 0; j < fenRows[i].length; j++) {
539 switch (fenRows[i].charAt(j)) {
540 case "k":
541 this.kingPos["b"] = [i, k];
542 break;
543 case "K":
544 this.kingPos["w"] = [i, k];
545 break;
546 default: {
547 const num = parseInt(fenRows[i].charAt(j), 10);
548 if (!isNaN(num)) k += num - 1;
549 }
550 }
551 k++;
552 }
553 }
554 }
555
556 // Some additional variables from FEN (variant dependant)
557 setOtherVariables(fen) {
558 // Set flags and enpassant:
559 const parsedFen = V.ParseFen(fen);
560 if (V.HasFlags) this.setFlags(parsedFen.flags);
561 if (V.HasEnpassant) {
562 const epSq =
563 parsedFen.enpassant != "-"
564 ? this.getEpSquare(parsedFen.enpassant)
565 : undefined;
566 this.epSquares = [epSq];
567 }
568 // Search for kings positions:
569 this.scanKings(fen);
570 }
571
572 /////////////////////
573 // GETTERS & SETTERS
574
575 static get size() {
576 return { x: 8, y: 8 };
577 }
578
579 // Color of thing on square (i,j). 'undefined' if square is empty
580 getColor(i, j) {
581 return this.board[i][j].charAt(0);
582 }
583
584 // Piece type on square (i,j). 'undefined' if square is empty
585 getPiece(i, j) {
586 return this.board[i][j].charAt(1);
587 }
588
589 // Get opponent color
590 static GetOppCol(color) {
591 return color == "w" ? "b" : "w";
592 }
593
594 // Pieces codes (for a clearer code)
595 static get PAWN() {
596 return "p";
597 }
598 static get ROOK() {
599 return "r";
600 }
601 static get KNIGHT() {
602 return "n";
603 }
604 static get BISHOP() {
605 return "b";
606 }
607 static get QUEEN() {
608 return "q";
609 }
610 static get KING() {
611 return "k";
612 }
613
614 // For FEN checking:
615 static get PIECES() {
616 return [V.PAWN, V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN, V.KING];
617 }
618
619 // Empty square
620 static get EMPTY() {
621 return "";
622 }
623
624 // Some pieces movements
625 static get steps() {
626 return {
627 r: [
628 [-1, 0],
629 [1, 0],
630 [0, -1],
631 [0, 1]
632 ],
633 n: [
634 [-1, -2],
635 [-1, 2],
636 [1, -2],
637 [1, 2],
638 [-2, -1],
639 [-2, 1],
640 [2, -1],
641 [2, 1]
642 ],
643 b: [
644 [-1, -1],
645 [-1, 1],
646 [1, -1],
647 [1, 1]
648 ]
649 };
650 }
651
652 ////////////////////
653 // MOVES GENERATION
654
655 // All possible moves from selected square
656 getPotentialMovesFrom([x, y]) {
657 switch (this.getPiece(x, y)) {
658 case V.PAWN:
659 return this.getPotentialPawnMoves([x, y]);
660 case V.ROOK:
661 return this.getPotentialRookMoves([x, y]);
662 case V.KNIGHT:
663 return this.getPotentialKnightMoves([x, y]);
664 case V.BISHOP:
665 return this.getPotentialBishopMoves([x, y]);
666 case V.QUEEN:
667 return this.getPotentialQueenMoves([x, y]);
668 case V.KING:
669 return this.getPotentialKingMoves([x, y]);
670 }
671 return []; //never reached
672 }
673
674 // Build a regular move from its initial and destination squares.
675 // tr: transformation
676 getBasicMove([sx, sy], [ex, ey], tr) {
677 const initColor = this.getColor(sx, sy);
678 const initPiece = this.board[sx][sy].charAt(1);
679 let mv = new Move({
680 appear: [
681 new PiPo({
682 x: ex,
683 y: ey,
684 c: tr ? tr.c : initColor,
685 p: tr ? tr.p : initPiece
686 })
687 ],
688 vanish: [
689 new PiPo({
690 x: sx,
691 y: sy,
692 c: initColor,
693 p: initPiece
694 })
695 ]
696 });
697
698 // The opponent piece disappears if we take it
699 if (this.board[ex][ey] != V.EMPTY) {
700 mv.vanish.push(
701 new PiPo({
702 x: ex,
703 y: ey,
704 c: this.getColor(ex, ey),
705 p: this.board[ex][ey].charAt(1)
706 })
707 );
708 }
709
710 return mv;
711 }
712
713 // Generic method to find possible moves of non-pawn pieces:
714 // "sliding or jumping"
715 getSlideNJumpMoves([x, y], steps, oneStep) {
716 let moves = [];
717 outerLoop: for (let step of steps) {
718 let i = x + step[0];
719 let j = y + step[1];
720 while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
721 moves.push(this.getBasicMove([x, y], [i, j]));
722 if (oneStep) continue outerLoop;
723 i += step[0];
724 j += step[1];
725 }
726 if (V.OnBoard(i, j) && this.canTake([x, y], [i, j]))
727 moves.push(this.getBasicMove([x, y], [i, j]));
728 }
729 return moves;
730 }
731
732 // Special case of en-passant captures: treated separately
733 getEnpassantCaptures([x, y], shiftX) {
734 const Lep = this.epSquares.length;
735 const epSquare = this.epSquares[Lep - 1]; //always at least one element
736 let enpassantMove = null;
737 if (
738 !!epSquare &&
739 epSquare.x == x + shiftX &&
740 Math.abs(epSquare.y - y) == 1
741 ) {
742 enpassantMove = this.getBasicMove([x, y], [epSquare.x, epSquare.y]);
743 enpassantMove.vanish.push({
744 x: x,
745 y: epSquare.y,
746 p: this.board[x][epSquare.y].charAt(1),
747 c: this.getColor(x, epSquare.y)
748 });
749 }
750 return !!enpassantMove ? [enpassantMove] : [];
751 }
752
753 // Consider all potential promotions:
754 addPawnMoves([x1, y1], [x2, y2], moves, promotions) {
755 let finalPieces = [V.PAWN];
756 const color = this.turn; //this.getColor(x1, y1);
757 const lastRank = (color == "w" ? 0 : V.size.x - 1);
758 if (x2 == lastRank) {
759 // promotions arg: special override for Hiddenqueen variant
760 if (!!promotions) finalPieces = promotions;
761 else if (!!V.PawnSpecs.promotions) finalPieces = V.PawnSpecs.promotions;
762 }
763 let tr = null;
764 for (let piece of finalPieces) {
765 tr = (piece != V.PAWN ? { c: color, p: piece } : null);
766 moves.push(this.getBasicMove([x1, y1], [x2, y2], tr));
767 }
768 }
769
770 // What are the pawn moves from square x,y ?
771 getPotentialPawnMoves([x, y], promotions) {
772 const color = this.turn; //this.getColor(x, y);
773 const [sizeX, sizeY] = [V.size.x, V.size.y];
774 const pawnShiftX = V.PawnSpecs.directions[color];
775 const firstRank = (color == "w" ? sizeX - 1 : 0);
776 const forward = (color == 'w' ? -1 : 1);
777
778 // Pawn movements in shiftX direction:
779 const getPawnMoves = (shiftX) => {
780 let moves = [];
781 // NOTE: next condition is generally true (no pawn on last rank)
782 if (x + shiftX >= 0 && x + shiftX < sizeX) {
783 if (this.board[x + shiftX][y] == V.EMPTY) {
784 // One square forward (or backward)
785 this.addPawnMoves([x, y], [x + shiftX, y], moves, promotions);
786 // Next condition because pawns on 1st rank can generally jump
787 if (
788 V.PawnSpecs.twoSquares &&
789 (
790 (color == 'w' && x >= V.size.x - 1 - V.PawnSpecs.initShift['w'])
791 ||
792 (color == 'b' && x <= V.PawnSpecs.initShift['b'])
793 )
794 ) {
795 if (
796 shiftX == forward &&
797 this.board[x + 2 * shiftX][y] == V.EMPTY
798 ) {
799 // Two squares jump
800 moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y]));
801 if (
802 V.PawnSpecs.threeSquares &&
803 this.board[x + 3 * shiftX][y] == V.EMPTY
804 ) {
805 // Three squares jump
806 moves.push(this.getBasicMove([x, y], [x + 3 * shiftX, y]));
807 }
808 }
809 }
810 }
811 // Captures
812 if (V.PawnSpecs.canCapture) {
813 for (let shiftY of [-1, 1]) {
814 if (y + shiftY >= 0 && y + shiftY < sizeY) {
815 if (
816 this.board[x + shiftX][y + shiftY] != V.EMPTY &&
817 this.canTake([x, y], [x + shiftX, y + shiftY])
818 ) {
819 this.addPawnMoves(
820 [x, y], [x + shiftX, y + shiftY],
821 moves, promotions
822 );
823 }
824 if (
825 V.PawnSpecs.captureBackward && shiftX == forward &&
826 x - shiftX >= 0 && x - shiftX < V.size.x &&
827 this.board[x - shiftX][y + shiftY] != V.EMPTY &&
828 this.canTake([x, y], [x - shiftX, y + shiftY])
829 ) {
830 this.addPawnMoves(
831 [x, y], [x - shiftX, y + shiftY],
832 moves, promotions
833 );
834 }
835 }
836 }
837 }
838 }
839 return moves;
840 }
841
842 let pMoves = getPawnMoves(pawnShiftX);
843 if (V.PawnSpecs.bidirectional)
844 pMoves = pMoves.concat(getPawnMoves(-pawnShiftX));
845
846 if (V.HasEnpassant) {
847 // NOTE: backward en-passant captures are not considered
848 // because no rules define them (for now).
849 Array.prototype.push.apply(
850 pMoves,
851 this.getEnpassantCaptures([x, y], pawnShiftX)
852 );
853 }
854
855 return pMoves;
856 }
857
858 // What are the rook moves from square x,y ?
859 getPotentialRookMoves(sq) {
860 return this.getSlideNJumpMoves(sq, V.steps[V.ROOK]);
861 }
862
863 // What are the knight moves from square x,y ?
864 getPotentialKnightMoves(sq) {
865 return this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT], "oneStep");
866 }
867
868 // What are the bishop moves from square x,y ?
869 getPotentialBishopMoves(sq) {
870 return this.getSlideNJumpMoves(sq, V.steps[V.BISHOP]);
871 }
872
873 // What are the queen moves from square x,y ?
874 getPotentialQueenMoves(sq) {
875 return this.getSlideNJumpMoves(
876 sq,
877 V.steps[V.ROOK].concat(V.steps[V.BISHOP])
878 );
879 }
880
881 // What are the king moves from square x,y ?
882 getPotentialKingMoves(sq) {
883 // Initialize with normal moves
884 let moves = this.getSlideNJumpMoves(
885 sq,
886 V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
887 "oneStep"
888 );
889 if (V.HasCastle && this.castleFlags[this.turn].some(v => v < V.size.y))
890 moves = moves.concat(this.getCastleMoves(sq));
891 return moves;
892 }
893
894 // "castleInCheck" arg to let some variants castle under check
895 getCastleMoves([x, y], finalSquares, castleInCheck, castleWith) {
896 const c = this.getColor(x, y);
897
898 // Castling ?
899 const oppCol = V.GetOppCol(c);
900 let moves = [];
901 let i = 0;
902 // King, then rook:
903 finalSquares = finalSquares || [ [2, 3], [V.size.y - 2, V.size.y - 3] ];
904 const castlingKing = this.board[x][y].charAt(1);
905 castlingCheck: for (
906 let castleSide = 0;
907 castleSide < 2;
908 castleSide++ //large, then small
909 ) {
910 if (this.castleFlags[c][castleSide] >= V.size.y) continue;
911 // If this code is reached, rook and king are on initial position
912
913 // NOTE: in some variants this is not a rook
914 const rookPos = this.castleFlags[c][castleSide];
915 const castlingPiece = this.board[x][rookPos].charAt(1);
916 if (
917 this.board[x][rookPos] == V.EMPTY ||
918 this.getColor(x, rookPos) != c ||
919 (!!castleWith && !castleWith.includes(castlingPiece))
920 ) {
921 // Rook is not here, or changed color (see Benedict)
922 continue;
923 }
924
925 // Nothing on the path of the king ? (and no checks)
926 const finDist = finalSquares[castleSide][0] - y;
927 let step = finDist / Math.max(1, Math.abs(finDist));
928 i = y;
929 do {
930 if (
931 (!castleInCheck && this.isAttacked([x, i], oppCol)) ||
932 (
933 this.board[x][i] != V.EMPTY &&
934 // NOTE: next check is enough, because of chessboard constraints
935 (this.getColor(x, i) != c || ![y, rookPos].includes(i))
936 )
937 ) {
938 continue castlingCheck;
939 }
940 i += step;
941 } while (i != finalSquares[castleSide][0]);
942
943 // Nothing on the path to the rook?
944 step = castleSide == 0 ? -1 : 1;
945 for (i = y + step; i != rookPos; i += step) {
946 if (this.board[x][i] != V.EMPTY) continue castlingCheck;
947 }
948
949 // Nothing on final squares, except maybe king and castling rook?
950 for (i = 0; i < 2; i++) {
951 if (
952 finalSquares[castleSide][i] != rookPos &&
953 this.board[x][finalSquares[castleSide][i]] != V.EMPTY &&
954 (
955 finalSquares[castleSide][i] != y ||
956 this.getColor(x, finalSquares[castleSide][i]) != c
957 )
958 ) {
959 continue castlingCheck;
960 }
961 }
962
963 // If this code is reached, castle is valid
964 moves.push(
965 new Move({
966 appear: [
967 new PiPo({
968 x: x,
969 y: finalSquares[castleSide][0],
970 p: castlingKing,
971 c: c
972 }),
973 new PiPo({
974 x: x,
975 y: finalSquares[castleSide][1],
976 p: castlingPiece,
977 c: c
978 })
979 ],
980 vanish: [
981 // King might be initially disguised (Titan...)
982 new PiPo({ x: x, y: y, p: castlingKing, c: c }),
983 new PiPo({ x: x, y: rookPos, p: castlingPiece, c: c })
984 ],
985 end:
986 Math.abs(y - rookPos) <= 2
987 ? { x: x, y: rookPos }
988 : { x: x, y: y + 2 * (castleSide == 0 ? -1 : 1) }
989 })
990 );
991 }
992
993 return moves;
994 }
995
996 ////////////////////
997 // MOVES VALIDATION
998
999 // For the interface: possible moves for the current turn from square sq
1000 getPossibleMovesFrom(sq) {
1001 return this.filterValid(this.getPotentialMovesFrom(sq));
1002 }
1003
1004 // TODO: promotions (into R,B,N,Q) should be filtered only once
1005 filterValid(moves) {
1006 if (moves.length == 0) return [];
1007 const color = this.turn;
1008 return moves.filter(m => {
1009 this.play(m);
1010 const res = !this.underCheck(color);
1011 this.undo(m);
1012 return res;
1013 });
1014 }
1015
1016 getAllPotentialMoves() {
1017 const color = this.turn;
1018 let potentialMoves = [];
1019 for (let i = 0; i < V.size.x; i++) {
1020 for (let j = 0; j < V.size.y; j++) {
1021 if (this.board[i][j] != V.EMPTY && this.getColor(i, j) == color) {
1022 Array.prototype.push.apply(
1023 potentialMoves,
1024 this.getPotentialMovesFrom([i, j])
1025 );
1026 }
1027 }
1028 }
1029 return potentialMoves;
1030 }
1031
1032 // Search for all valid moves considering current turn
1033 // (for engine and game end)
1034 getAllValidMoves() {
1035 return this.filterValid(this.getAllPotentialMoves());
1036 }
1037
1038 // Stop at the first move found
1039 // TODO: not really, it explores all moves from a square (one is enough).
1040 atLeastOneMove() {
1041 const color = this.turn;
1042 for (let i = 0; i < V.size.x; i++) {
1043 for (let j = 0; j < V.size.y; j++) {
1044 if (this.board[i][j] != V.EMPTY && this.getColor(i, j) == color) {
1045 const moves = this.getPotentialMovesFrom([i, j]);
1046 if (moves.length > 0) {
1047 for (let k = 0; k < moves.length; k++)
1048 if (this.filterValid([moves[k]]).length > 0) return true;
1049 }
1050 }
1051 }
1052 }
1053 return false;
1054 }
1055
1056 // Check if pieces of given color are attacking (king) on square x,y
1057 isAttacked(sq, color) {
1058 return (
1059 this.isAttackedByPawn(sq, color) ||
1060 this.isAttackedByRook(sq, color) ||
1061 this.isAttackedByKnight(sq, color) ||
1062 this.isAttackedByBishop(sq, color) ||
1063 this.isAttackedByQueen(sq, color) ||
1064 this.isAttackedByKing(sq, color)
1065 );
1066 }
1067
1068 // Generic method for non-pawn pieces ("sliding or jumping"):
1069 // is x,y attacked by a piece of given color ?
1070 isAttackedBySlideNJump([x, y], color, piece, steps, oneStep) {
1071 for (let step of steps) {
1072 let rx = x + step[0],
1073 ry = y + step[1];
1074 while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
1075 rx += step[0];
1076 ry += step[1];
1077 }
1078 if (
1079 V.OnBoard(rx, ry) &&
1080 this.getPiece(rx, ry) == piece &&
1081 this.getColor(rx, ry) == color
1082 ) {
1083 return true;
1084 }
1085 }
1086 return false;
1087 }
1088
1089 // Is square x,y attacked by 'color' pawns ?
1090 isAttackedByPawn(sq, color) {
1091 const pawnShift = (color == "w" ? 1 : -1);
1092 return this.isAttackedBySlideNJump(
1093 sq,
1094 color,
1095 V.PAWN,
1096 [[pawnShift, 1], [pawnShift, -1]],
1097 "oneStep"
1098 );
1099 }
1100
1101 // Is square x,y attacked by 'color' rooks ?
1102 isAttackedByRook(sq, color) {
1103 return this.isAttackedBySlideNJump(sq, color, V.ROOK, V.steps[V.ROOK]);
1104 }
1105
1106 // Is square x,y attacked by 'color' knights ?
1107 isAttackedByKnight(sq, color) {
1108 return this.isAttackedBySlideNJump(
1109 sq,
1110 color,
1111 V.KNIGHT,
1112 V.steps[V.KNIGHT],
1113 "oneStep"
1114 );
1115 }
1116
1117 // Is square x,y attacked by 'color' bishops ?
1118 isAttackedByBishop(sq, color) {
1119 return this.isAttackedBySlideNJump(sq, color, V.BISHOP, V.steps[V.BISHOP]);
1120 }
1121
1122 // Is square x,y attacked by 'color' queens ?
1123 isAttackedByQueen(sq, color) {
1124 return this.isAttackedBySlideNJump(
1125 sq,
1126 color,
1127 V.QUEEN,
1128 V.steps[V.ROOK].concat(V.steps[V.BISHOP])
1129 );
1130 }
1131
1132 // Is square x,y attacked by 'color' king(s) ?
1133 isAttackedByKing(sq, color) {
1134 return this.isAttackedBySlideNJump(
1135 sq,
1136 color,
1137 V.KING,
1138 V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
1139 "oneStep"
1140 );
1141 }
1142
1143 // Is color under check after his move ?
1144 underCheck(color) {
1145 return this.isAttacked(this.kingPos[color], V.GetOppCol(color));
1146 }
1147
1148 /////////////////
1149 // MOVES PLAYING
1150
1151 // Apply a move on board
1152 static PlayOnBoard(board, move) {
1153 for (let psq of move.vanish) board[psq.x][psq.y] = V.EMPTY;
1154 for (let psq of move.appear) board[psq.x][psq.y] = psq.c + psq.p;
1155 }
1156 // Un-apply the played move
1157 static UndoOnBoard(board, move) {
1158 for (let psq of move.appear) board[psq.x][psq.y] = V.EMPTY;
1159 for (let psq of move.vanish) board[psq.x][psq.y] = psq.c + psq.p;
1160 }
1161
1162 prePlay() {}
1163
1164 play(move) {
1165 // DEBUG:
1166 // if (!this.states) this.states = [];
1167 // const stateFen = this.getFen() + JSON.stringify(this.kingPos);
1168 // this.states.push(stateFen);
1169
1170 this.prePlay(move);
1171 // Save flags (for undo)
1172 if (V.HasFlags) move.flags = JSON.stringify(this.aggregateFlags());
1173 if (V.HasEnpassant) this.epSquares.push(this.getEpSquare(move));
1174 V.PlayOnBoard(this.board, move);
1175 this.turn = V.GetOppCol(this.turn);
1176 this.movesCount++;
1177 this.postPlay(move);
1178 }
1179
1180 updateCastleFlags(move, piece, color) {
1181 const c = color || V.GetOppCol(this.turn);
1182 const firstRank = (c == "w" ? V.size.x - 1 : 0);
1183 // Update castling flags if rooks are moved
1184 const oppCol = this.turn;
1185 const oppFirstRank = V.size.x - 1 - firstRank;
1186 if (piece == V.KING && move.appear.length > 0)
1187 this.castleFlags[c] = [V.size.y, V.size.y];
1188 else if (
1189 move.start.x == firstRank && //our rook moves?
1190 this.castleFlags[c].includes(move.start.y)
1191 ) {
1192 const flagIdx = (move.start.y == this.castleFlags[c][0] ? 0 : 1);
1193 this.castleFlags[c][flagIdx] = V.size.y;
1194 }
1195 // NOTE: not "else if" because a rook could take an opposing rook
1196 if (
1197 move.end.x == oppFirstRank && //we took opponent rook?
1198 this.castleFlags[oppCol].includes(move.end.y)
1199 ) {
1200 const flagIdx = (move.end.y == this.castleFlags[oppCol][0] ? 0 : 1);
1201 this.castleFlags[oppCol][flagIdx] = V.size.y;
1202 }
1203 }
1204
1205 // After move is played, update variables + flags
1206 postPlay(move) {
1207 const c = V.GetOppCol(this.turn);
1208 let piece = undefined;
1209 if (move.vanish.length >= 1)
1210 // Usual case, something is moved
1211 piece = move.vanish[0].p;
1212 else
1213 // Crazyhouse-like variants
1214 piece = move.appear[0].p;
1215
1216 // Update king position + flags
1217 if (piece == V.KING && move.appear.length > 0)
1218 this.kingPos[c] = [move.appear[0].x, move.appear[0].y];
1219 if (V.HasCastle) this.updateCastleFlags(move, piece);
1220 }
1221
1222 preUndo() {}
1223
1224 undo(move) {
1225 this.preUndo(move);
1226 if (V.HasEnpassant) this.epSquares.pop();
1227 if (V.HasFlags) this.disaggregateFlags(JSON.parse(move.flags));
1228 V.UndoOnBoard(this.board, move);
1229 this.turn = V.GetOppCol(this.turn);
1230 this.movesCount--;
1231 this.postUndo(move);
1232
1233 // DEBUG:
1234 // const stateFen = this.getFen() + JSON.stringify(this.kingPos);
1235 // if (stateFen != this.states[this.states.length-1]) debugger;
1236 // this.states.pop();
1237 }
1238
1239 // After move is undo-ed *and flags resetted*, un-update other variables
1240 // TODO: more symmetry, by storing flags increment in move (?!)
1241 postUndo(move) {
1242 // (Potentially) Reset king position
1243 const c = this.getColor(move.start.x, move.start.y);
1244 if (this.getPiece(move.start.x, move.start.y) == V.KING)
1245 this.kingPos[c] = [move.start.x, move.start.y];
1246 }
1247
1248 ///////////////
1249 // END OF GAME
1250
1251 // What is the score ? (Interesting if game is over)
1252 getCurrentScore() {
1253 if (this.atLeastOneMove()) return "*";
1254 // Game over
1255 const color = this.turn;
1256 // No valid move: stalemate or checkmate?
1257 if (!this.underCheck(color)) return "1/2";
1258 // OK, checkmate
1259 return (color == "w" ? "0-1" : "1-0");
1260 }
1261
1262 ///////////////
1263 // ENGINE PLAY
1264
1265 // Pieces values
1266 static get VALUES() {
1267 return {
1268 p: 1,
1269 r: 5,
1270 n: 3,
1271 b: 3,
1272 q: 9,
1273 k: 1000
1274 };
1275 }
1276
1277 // "Checkmate" (unreachable eval)
1278 static get INFINITY() {
1279 return 9999;
1280 }
1281
1282 // At this value or above, the game is over
1283 static get THRESHOLD_MATE() {
1284 return V.INFINITY;
1285 }
1286
1287 // Search depth: 1,2 for e.g. higher branching factor, 4 for smaller
1288 static get SEARCH_DEPTH() {
1289 return 3;
1290 }
1291
1292 // 'movesList' arg for some variants to provide a custom list
1293 getComputerMove(movesList) {
1294 const maxeval = V.INFINITY;
1295 const color = this.turn;
1296 let moves1 = movesList || this.getAllValidMoves();
1297
1298 if (moves1.length == 0)
1299 // TODO: this situation should not happen
1300 return null;
1301
1302 // Rank moves using a min-max at depth 2 (if search_depth >= 2!)
1303 for (let i = 0; i < moves1.length; i++) {
1304 this.play(moves1[i]);
1305 const score1 = this.getCurrentScore();
1306 if (score1 != "*") {
1307 moves1[i].eval =
1308 score1 == "1/2"
1309 ? 0
1310 : (score1 == "1-0" ? 1 : -1) * maxeval;
1311 }
1312 if (V.SEARCH_DEPTH == 1 || score1 != "*") {
1313 if (!moves1[i].eval) moves1[i].eval = this.evalPosition();
1314 this.undo(moves1[i]);
1315 continue;
1316 }
1317 // Initial self evaluation is very low: "I'm checkmated"
1318 moves1[i].eval = (color == "w" ? -1 : 1) * maxeval;
1319 // Initial enemy evaluation is very low too, for him
1320 let eval2 = (color == "w" ? 1 : -1) * maxeval;
1321 // Second half-move:
1322 let moves2 = this.getAllValidMoves();
1323 for (let j = 0; j < moves2.length; j++) {
1324 this.play(moves2[j]);
1325 const score2 = this.getCurrentScore();
1326 let evalPos = 0; //1/2 value
1327 switch (score2) {
1328 case "*":
1329 evalPos = this.evalPosition();
1330 break;
1331 case "1-0":
1332 evalPos = maxeval;
1333 break;
1334 case "0-1":
1335 evalPos = -maxeval;
1336 break;
1337 }
1338 if (
1339 (color == "w" && evalPos < eval2) ||
1340 (color == "b" && evalPos > eval2)
1341 ) {
1342 eval2 = evalPos;
1343 }
1344 this.undo(moves2[j]);
1345 }
1346 if (
1347 (color == "w" && eval2 > moves1[i].eval) ||
1348 (color == "b" && eval2 < moves1[i].eval)
1349 ) {
1350 moves1[i].eval = eval2;
1351 }
1352 this.undo(moves1[i]);
1353 }
1354 moves1.sort((a, b) => {
1355 return (color == "w" ? 1 : -1) * (b.eval - a.eval);
1356 });
1357 // console.log(moves1.map(m => { return [this.getNotation(m), m.eval]; }));
1358
1359 // Skip depth 3+ if we found a checkmate (or if we are checkmated in 1...)
1360 if (V.SEARCH_DEPTH >= 3 && Math.abs(moves1[0].eval) < V.THRESHOLD_MATE) {
1361 for (let i = 0; i < moves1.length; i++) {
1362 this.play(moves1[i]);
1363 // 0.1 * oldEval : heuristic to avoid some bad moves (not all...)
1364 moves1[i].eval =
1365 0.1 * moves1[i].eval +
1366 this.alphabeta(V.SEARCH_DEPTH - 1, -maxeval, maxeval);
1367 this.undo(moves1[i]);
1368 }
1369 moves1.sort((a, b) => {
1370 return (color == "w" ? 1 : -1) * (b.eval - a.eval);
1371 });
1372 }
1373
1374 let candidates = [0];
1375 for (let i = 1; i < moves1.length && moves1[i].eval == moves1[0].eval; i++)
1376 candidates.push(i);
1377 return moves1[candidates[randInt(candidates.length)]];
1378 }
1379
1380 alphabeta(depth, alpha, beta) {
1381 const maxeval = V.INFINITY;
1382 const color = this.turn;
1383 const score = this.getCurrentScore();
1384 if (score != "*")
1385 return score == "1/2" ? 0 : (score == "1-0" ? 1 : -1) * maxeval;
1386 if (depth == 0) return this.evalPosition();
1387 const moves = this.getAllValidMoves();
1388 let v = color == "w" ? -maxeval : maxeval;
1389 if (color == "w") {
1390 for (let i = 0; i < moves.length; i++) {
1391 this.play(moves[i]);
1392 v = Math.max(v, this.alphabeta(depth - 1, alpha, beta));
1393 this.undo(moves[i]);
1394 alpha = Math.max(alpha, v);
1395 if (alpha >= beta) break; //beta cutoff
1396 }
1397 }
1398 else {
1399 // color=="b"
1400 for (let i = 0; i < moves.length; i++) {
1401 this.play(moves[i]);
1402 v = Math.min(v, this.alphabeta(depth - 1, alpha, beta));
1403 this.undo(moves[i]);
1404 beta = Math.min(beta, v);
1405 if (alpha >= beta) break; //alpha cutoff
1406 }
1407 }
1408 return v;
1409 }
1410
1411 evalPosition() {
1412 let evaluation = 0;
1413 // Just count material for now
1414 for (let i = 0; i < V.size.x; i++) {
1415 for (let j = 0; j < V.size.y; j++) {
1416 if (this.board[i][j] != V.EMPTY) {
1417 const sign = this.getColor(i, j) == "w" ? 1 : -1;
1418 evaluation += sign * V.VALUES[this.getPiece(i, j)];
1419 }
1420 }
1421 }
1422 return evaluation;
1423 }
1424
1425 /////////////////////////
1426 // MOVES + GAME NOTATION
1427 /////////////////////////
1428
1429 // Context: just before move is played, turn hasn't changed
1430 // TODO: un-ambiguous notation (switch on piece type, check directions...)
1431 getNotation(move) {
1432 if (move.appear.length == 2 && move.appear[0].p == V.KING)
1433 // Castle
1434 return move.end.y < move.start.y ? "0-0-0" : "0-0";
1435
1436 // Translate final square
1437 const finalSquare = V.CoordsToSquare(move.end);
1438
1439 const piece = this.getPiece(move.start.x, move.start.y);
1440 if (piece == V.PAWN) {
1441 // Pawn move
1442 let notation = "";
1443 if (move.vanish.length > move.appear.length) {
1444 // Capture
1445 const startColumn = V.CoordToColumn(move.start.y);
1446 notation = startColumn + "x" + finalSquare;
1447 }
1448 else notation = finalSquare;
1449 if (move.appear.length > 0 && move.appear[0].p != V.PAWN)
1450 // Promotion
1451 notation += "=" + move.appear[0].p.toUpperCase();
1452 return notation;
1453 }
1454 // Piece movement
1455 return (
1456 piece.toUpperCase() +
1457 (move.vanish.length > move.appear.length ? "x" : "") +
1458 finalSquare
1459 );
1460 }
1461
1462 static GetUnambiguousNotation(move) {
1463 // Machine-readable format with all the informations about the move
1464 return (
1465 (!!move.start && V.OnBoard(move.start.x, move.start.y)
1466 ? V.CoordsToSquare(move.start)
1467 : "-"
1468 ) + "." +
1469 (!!move.end && V.OnBoard(move.end.x, move.end.y)
1470 ? V.CoordsToSquare(move.end)
1471 : "-"
1472 ) + " " +
1473 (!!move.appear && move.appear.length > 0
1474 ? move.appear.map(a =>
1475 a.c + a.p + V.CoordsToSquare({ x: a.x, y: a.y })).join(".")
1476 : "-"
1477 ) + "/" +
1478 (!!move.vanish && move.vanish.length > 0
1479 ? move.vanish.map(a =>
1480 a.c + a.p + V.CoordsToSquare({ x: a.x, y: a.y })).join(".")
1481 : "-"
1482 )
1483 );
1484 }
1485
1486 };