client/src/variants/Extinction.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export class ExtinctionRules extends ChessRules {
   4   static get PawnSpecs() {
   5     return Object.assign(
   6       {},
   7       ChessRules.PawnSpecs,
   8       { promotions: ChessRules.PawnSpecs.promotions.concat([V.KING]) }
   9     );
  10   }
  11
  12   static IsGoodPosition(position) {
  13     if (!ChessRules.IsGoodPosition(position))
  14       return false;
  15     // Also check that each piece type is present
  16     const rows = position.split("/");
  17     let pieces = {};
  18     for (let row of rows) {
  19       for (let i = 0; i < row.length; i++) {
  20         if (isNaN(parseInt(row[i])) && !pieces[row[i]])
  21           pieces[row[i]] = true;
  22       }
  23     }
  24     if (Object.keys(pieces).length != 12)
  25       return false;
  26     return true;
  27   }
  28
  29   setOtherVariables(fen) {
  30     super.setOtherVariables(fen);
  31     const pos = V.ParseFen(fen).position;
  32     // NOTE: no need for safety "|| []", because each piece type must be present
  33     // (otherwise game is already over!)
  34     this.material = {
  35       w: {
  36         [V.KING]: pos.match(/K/g).length,
  37         [V.QUEEN]: pos.match(/Q/g).length,
  38         [V.ROOK]: pos.match(/R/g).length,
  39         [V.KNIGHT]: pos.match(/N/g).length,
  40         [V.BISHOP]: pos.match(/B/g).length,
  41         [V.PAWN]: pos.match(/P/g).length
  42       },
  43       b: {
  44         [V.KING]: pos.match(/k/g).length,
  45         [V.QUEEN]: pos.match(/q/g).length,
  46         [V.ROOK]: pos.match(/r/g).length,
  47         [V.KNIGHT]: pos.match(/n/g).length,
  48         [V.BISHOP]: pos.match(/b/g).length,
  49         [V.PAWN]: pos.match(/p/g).length
  50       }
  51     };
  52   }
  53
  54   // TODO: verify this assertion
  55   atLeastOneMove() {
  56     return true; //always at least one possible move
  57   }
  58
  59   filterValid(moves) {
  60     return moves; //there is no check
  61   }
  62
  63   getCheckSquares() {
  64     return [];
  65   }
  66
  67   postPlay(move) {
  68     super.postPlay(move);
  69     // Treat the promotion case: (not the capture part)
  70     if (move.appear[0].p != move.vanish[0].p) {
  71       this.material[move.appear[0].c][move.appear[0].p]++;
  72       this.material[move.appear[0].c][V.PAWN]--;
  73     }
  74     if (move.vanish.length == 2 && move.appear.length == 1)
  75       //capture
  76       this.material[move.vanish[1].c][move.vanish[1].p]--;
  77   }
  78
  79   postUndo(move) {
  80     super.postUndo(move);
  81     if (move.appear[0].p != move.vanish[0].p) {
  82       this.material[move.appear[0].c][move.appear[0].p]--;
  83       this.material[move.appear[0].c][V.PAWN]++;
  84     }
  85     if (move.vanish.length == 2 && move.appear.length == 1)
  86       this.material[move.vanish[1].c][move.vanish[1].p]++;
  87   }
  88
  89   getCurrentScore() {
  90     if (this.atLeastOneMove()) {
  91       // Game not over?
  92       const color = this.turn;
  93       if (
  94         Object.keys(this.material[color]).some(p => {
  95           return this.material[color][p] == 0;
  96         })
  97       ) {
  98         return this.turn == "w" ? "0-1" : "1-0";
  99       }
 100       return "*";
 101     }
 102     return this.turn == "w" ? "0-1" : "1-0"; //NOTE: currently unreachable...
 103   }
 104
 105   evalPosition() {
 106     const color = this.turn;
 107     if (
 108       Object.keys(this.material[color]).some(p => {
 109         return this.material[color][p] == 0;
 110       })
 111     ) {
 112       // Very negative (resp. positive) if white (reps. black) pieces set is incomplete
 113       return (color == "w" ? -1 : 1) * V.INFINITY;
 114     }
 115     return super.evalPosition();
 116   }
 117 };