public/javascripts/variants/Checkered.js

   1 class CheckeredRules extends ChessRules
   2 {
   3     static getPpath(b)
   4     {
   5         return b[0]=='c' ? "Checkered/"+b : b;
   6     }
   7     static board2fen(b)
   8     {
   9         const checkered_codes = {
  10             'p': 's',
  11             'q': 't',
  12             'r': 'u',
  13             'b': 'c',
  14             'n': 'o',
  15         };
  16         if (b[0]=="c")
  17             return checkered_codes[b[1]];
  18         return ChessRules.board2fen(b);
  19     }
  20     static fen2board(f)
  21     {
  22         // Tolerate upper-case versions of checkered pieces (why not?)
  23         const checkered_pieces = {
  24             's': 'p',
  25             'S': 'p',
  26             't': 'q',
  27             'T': 'q',
  28             'u': 'r',
  29             'U': 'r',
  30             'c': 'b',
  31             'C': 'b',
  32             'o': 'n',
  33             'O': 'n',
  34         };
  35         if (Object.keys(checkered_pieces).includes(f))
  36             return 'c'+checkered_pieces[f];
  37         return ChessRules.fen2board(f);
  38     }
  39
  40     static get PIECES() {
  41         return ChessRules.PIECES.concat(['s','t','u','c','o']);
  42     }
  43
  44     static IsGoodFlags(flags)
  45     {
  46         // 4 for castle + 16 for pawns
  47         return !!flags.match(/^[01]{20,20}$/);
  48     }
  49
  50     setFlags(fenflags)
  51     {
  52         super.setFlags(fenflags); //castleFlags
  53         this.pawnFlags =
  54         {
  55             "w": _.map(_.range(8), i => true), //pawns can move 2 squares?
  56             "b": _.map(_.range(8), i => true)
  57         };
  58         if (!fenflags)
  59             return;
  60         const flags = fenflags.substr(4); //skip first 4 digits, for castle
  61         for (let c of ['w','b'])
  62         {
  63             for (let i=0; i<8; i++)
  64                 this.pawnFlags[c][i] = (flags.charAt((c=='w'?0:8)+i) == '1');
  65         }
  66     }
  67
  68     // Aggregates flags into one object
  69     get flags() {
  70         return [this.castleFlags, this.pawnFlags];
  71     }
  72
  73     // Reverse operation
  74     parseFlags(flags)
  75     {
  76         this.castleFlags = flags[0];
  77         this.pawnFlags = flags[1];
  78     }
  79
  80     canTake([x1,y1], [x2,y2])
  81     {
  82         const color1 = this.getColor(x1,y1);
  83         const color2 = this.getColor(x2,y2);
  84         // Checkered aren't captured
  85         return color1 != color2 && color2 != 'c' && (color1 != 'c' || color2 != this.turn);
  86     }
  87
  88     // Post-processing: apply "checkerization" of standard moves
  89     getPotentialMovesFrom([x,y])
  90     {
  91         let standardMoves = super.getPotentialMovesFrom([x,y]);
  92         const lastRank = this.turn == "w" ? 0 : 7;
  93         if (this.getPiece(x,y) == V.KING)
  94             return standardMoves; //king has to be treated differently (for castles)
  95         let moves = [];
  96         standardMoves.forEach(m => {
  97             if (m.vanish[0].p == V.PAWN)
  98             {
  99                 if (Math.abs(m.end.x-m.start.x)==2 && !this.pawnFlags[this.turn][m.start.y])
 100                     return; //skip forbidden 2-squares jumps
 101                 if (this.board[m.end.x][m.end.y] == V.EMPTY && m.vanish.length==2
 102                     && this.getColor(m.start.x,m.start.y) == 'c')
 103                 {
 104                     return; //checkered pawns cannot take en-passant
 105                 }
 106             }
 107             if (m.vanish.length == 1)
 108                 moves.push(m); //no capture
 109             else
 110             {
 111                 // A capture occured (m.vanish.length == 2)
 112                 m.appear[0].c = "c";
 113                 moves.push(m);
 114                 if (m.appear[0].p != m.vanish[1].p //avoid promotions (already treated):
 115                     && (m.vanish[0].p != V.PAWN || m.end.x != lastRank))
 116                 {
 117                     // Add transformation into captured piece
 118                     let m2 = JSON.parse(JSON.stringify(m));
 119                     m2.appear[0].p = m.vanish[1].p;
 120                     moves.push(m2);
 121                 }
 122             }
 123         });
 124         return moves;
 125     }
 126
 127     canIplay(side, [x,y])
 128     {
 129         return (side == this.turn && [side,'c'].includes(this.getColor(x,y)));
 130     }
 131
 132     // Does m2 un-do m1 ? (to disallow undoing checkered moves)
 133     oppositeMoves(m1, m2)
 134     {
 135         return m1.appear.length == 1 && m2.appear.length == 1
 136             && m1.vanish.length == 1 && m2.vanish.length == 1
 137             && m1.start.x == m2.end.x && m1.end.x == m2.start.x
 138             && m1.start.y == m2.end.y && m1.end.y == m2.start.y
 139             && m1.appear[0].c == m2.vanish[0].c && m1.appear[0].p == m2.vanish[0].p
 140             && m1.vanish[0].c == m2.appear[0].c && m1.vanish[0].p == m2.appear[0].p;
 141     }
 142
 143     filterValid(moves)
 144     {
 145         if (moves.length == 0)
 146             return [];
 147         const color = this.turn;
 148         return moves.filter(m => {
 149             const L = this.moves.length;
 150             if (L > 0 && this.oppositeMoves(this.moves[L-1], m))
 151                 return false;
 152             return !this.underCheck(m);
 153         });
 154     }
 155
 156     isAttackedByPawn([x,y], colors)
 157     {
 158         for (let c of colors)
 159         {
 160             const color = (c=="c" ? this.turn : c);
 161             let pawnShift = (color=="w" ? 1 : -1);
 162             if (x+pawnShift>=0 && x+pawnShift<8)
 163             {
 164                 for (let i of [-1,1])
 165                 {
 166                     if (y+i>=0 && y+i<8 && this.getPiece(x+pawnShift,y+i)==V.PAWN
 167                         && this.getColor(x+pawnShift,y+i)==c)
 168                     {
 169                         return true;
 170                     }
 171                 }
 172             }
 173         }
 174         return false;
 175     }
 176
 177     underCheck(move)
 178     {
 179         const color = this.turn;
 180         this.play(move);
 181         let res = this.isAttacked(this.kingPos[color], [this.getOppCol(color),'c']);
 182         this.undo(move);
 183         return res;
 184     }
 185
 186     getCheckSquares(move)
 187     {
 188         this.play(move);
 189         const color = this.turn;
 190         this.moves.push(move); //artifically change turn, for checkered pawns (TODO)
 191         const kingAttacked = this.isAttacked(
 192             this.kingPos[color], [this.getOppCol(color),'c']);
 193         let res = kingAttacked
 194             ? [ JSON.parse(JSON.stringify(this.kingPos[color])) ] //need to duplicate!
 195             : [ ];
 196         this.moves.pop();
 197         this.undo(move);
 198         return res;
 199     }
 200
 201     updateVariables(move)
 202     {
 203         super.updateVariables(move);
 204         // Does this move turn off a 2-squares pawn flag?
 205         const secondRank = [1,6];
 206         if (secondRank.includes(move.start.x) && move.vanish[0].p == V.PAWN)
 207             this.pawnFlags[move.start.x==6 ? "w" : "b"][move.start.y] = false;
 208     }
 209
 210     checkGameEnd()
 211     {
 212         const color = this.turn;
 213         // Artifically change turn, for checkered pawns
 214         this.turn = this.getOppCol(this.turn);
 215         const res = this.isAttacked(this.kingPos[color], [this.getOppCol(color),'c'])
 216             ? (color == "w" ? "0-1" : "1-0")
 217             : "1/2";
 218         this.turn = this.getOppCol(this.turn);
 219         return res;
 220     }
 221
 222     evalPosition()
 223     {
 224         let evaluation = 0;
 225         //Just count material for now, considering checkered neutral (...)
 226         for (let i=0; i<V.size.x; i++)
 227         {
 228             for (let j=0; j<V.size.y; j++)
 229             {
 230                 if (this.board[i][j] != V.EMPTY)
 231                 {
 232                     const sqColor = this.getColor(i,j);
 233                     const sign = sqColor == "w" ? 1 : (sqColor=="b" ? -1 : 0);
 234                     evaluation += sign * V.VALUES[this.getPiece(i,j)];
 235                 }
 236             }
 237         }
 238         return evaluation;
 239     }
 240
 241     static GenRandInitFen()
 242     {
 243         const randFen = ChessRules.GenRandInitFen();
 244         // Add 16 pawns flags:
 245         return randFen.replace(" 1111 w", " 11111111111111111111 w");
 246     }
 247
 248     getFlagsFen()
 249     {
 250         let fen = super.getFlagsFen();
 251         // Add pawns flags
 252         for (let c of ['w','b'])
 253         {
 254             for (let i=0; i<8; i++)
 255                 fen += this.pawnFlags[c][i] ? '1' : '0';
 256         }
 257         return fen;
 258     }
 259
 260     getNotation(move)
 261     {
 262         if (move.appear.length == 2)
 263         {
 264             // Castle
 265             if (move.end.y < move.start.y)
 266                 return "0-0-0";
 267             else
 268                 return "0-0";
 269         }
 270
 271         // Translate final square
 272         let finalSquare =
 273             String.fromCharCode(97 + move.end.y) + (V.size.x-move.end.x);
 274
 275         let piece = this.getPiece(move.start.x, move.start.y);
 276         if (piece == V.PAWN)
 277         {
 278             // Pawn move
 279             let notation = "";
 280             if (move.vanish.length > 1)
 281             {
 282                 // Capture
 283                 let startColumn = String.fromCharCode(97 + move.start.y);
 284                 notation = startColumn + "x" + finalSquare +
 285                     "=" + move.appear[0].p.toUpperCase();
 286             }
 287             else //no capture
 288             {
 289                 notation = finalSquare;
 290                 if (move.appear.length > 0 && piece != move.appear[0].p) //promotion
 291                     notation += "=" + move.appear[0].p.toUpperCase();
 292             }
 293             return notation;
 294         }
 295
 296         else
 297         {
 298             // Piece movement
 299             return piece.toUpperCase() + (move.vanish.length > 1 ? "x" : "") + finalSquare
 300                 + (move.vanish.length > 1 ? "=" + move.appear[0].p.toUpperCase() : "");
 301         }
 302     }
 303 }