client/src/variants/Extinction.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export const VariantRules = class  ExtinctionRules extends ChessRules
   4 {
   5   setOtherVariables(fen)
   6   {
   7     super.setOtherVariables(fen);
   8     const pos = V.ParseFen(fen).position;
   9     // NOTE: no need for safety "|| []", because each piece type must be present
  10     // (otherwise game is already over!)
  11     this.material =
  12     {
  13       "w":
  14       {
  15         [V.KING]: pos.match(/K/g).length,
  16         [V.QUEEN]: pos.match(/Q/g).length,
  17         [V.ROOK]: pos.match(/R/g).length,
  18         [V.KNIGHT]: pos.match(/N/g).length,
  19         [V.BISHOP]: pos.match(/B/g).length,
  20         [V.PAWN]: pos.match(/P/g).length
  21       },
  22       "b":
  23       {
  24         [V.KING]: pos.match(/k/g).length,
  25         [V.QUEEN]: pos.match(/q/g).length,
  26         [V.ROOK]: pos.match(/r/g).length,
  27         [V.KNIGHT]: pos.match(/n/g).length,
  28         [V.BISHOP]: pos.match(/b/g).length,
  29         [V.PAWN]: pos.match(/p/g).length
  30       }
  31     };
  32   }
  33
  34   getPotentialPawnMoves([x,y])
  35   {
  36     let moves = super.getPotentialPawnMoves([x,y]);
  37     // Add potential promotions into king
  38     const color = this.turn;
  39     const shift = (color == "w" ? -1 : 1);
  40     const lastRank = (color == "w" ? 0 : V.size.x-1);
  41
  42     if (x+shift == lastRank)
  43     {
  44       // Normal move
  45       if (this.board[x+shift][y] == V.EMPTY)
  46         moves.push(this.getBasicMove([x,y], [x+shift,y], {c:color,p:V.KING}));
  47       // Captures
  48       if (y>0 && this.board[x+shift][y-1] != V.EMPTY
  49         && this.canTake([x,y], [x+shift,y-1]))
  50       {
  51         moves.push(this.getBasicMove([x,y], [x+shift,y-1], {c:color,p:V.KING}));
  52       }
  53       if (y<V.size.y-1 && this.board[x+shift][y+1] != V.EMPTY
  54         && this.canTake([x,y], [x+shift,y+1]))
  55       {
  56         moves.push(this.getBasicMove([x,y], [x+shift,y+1], {c:color,p:V.KING}));
  57       }
  58     }
  59
  60     return moves;
  61   }
  62
  63   // TODO: verify this assertion
  64   atLeastOneMove()
  65   {
  66     return true; //always at least one possible move
  67   }
  68
  69   underCheck(color)
  70   {
  71     return false; //there is no check
  72   }
  73
  74   getCheckSquares(color)
  75   {
  76     return [];
  77   }
  78
  79   updateVariables(move)
  80   {
  81     super.updateVariables(move);
  82     // Treat the promotion case: (not the capture part)
  83     if (move.appear[0].p != move.vanish[0].p)
  84     {
  85       this.material[move.appear[0].c][move.appear[0].p]++;
  86       this.material[move.appear[0].c][V.PAWN]--;
  87     }
  88     if (move.vanish.length==2 && move.appear.length==1) //capture
  89       this.material[move.vanish[1].c][move.vanish[1].p]--;
  90   }
  91
  92   unupdateVariables(move)
  93   {
  94     super.unupdateVariables(move);
  95     if (move.appear[0].p != move.vanish[0].p)
  96     {
  97       this.material[move.appear[0].c][move.appear[0].p]--;
  98       this.material[move.appear[0].c][V.PAWN]++;
  99     }
 100     if (move.vanish.length==2 && move.appear.length==1)
 101       this.material[move.vanish[1].c][move.vanish[1].p]++;
 102   }
 103
 104   getCurrentScore()
 105   {
 106     if (this.atLeastOneMove()) // game not over?
 107     {
 108       const color = this.turn;
 109       if (Object.keys(this.material[color]).some(
 110         p => { return this.material[color][p] == 0; }))
 111       {
 112         return (this.turn == "w" ? "0-1" : "1-0");
 113       }
 114       return "*";
 115     }
 116
 117     return (this.turn == "w" ? "0-1" : "1-0"); //NOTE: currently unreachable...
 118   }
 119
 120   evalPosition()
 121   {
 122     const color = this.turn;
 123     if (Object.keys(this.material[color]).some(
 124       p => { return this.material[color][p] == 0; }))
 125     {
 126       // Very negative (resp. positive) if white (reps. black) pieces set is incomplete
 127       return (color=="w"?-1:1) * V.INFINITY;
 128     }
 129     return super.evalPosition();
 130   }
 131 }