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