--- /dev/null
+class ExtinctionRules extends ChessRules
+{
+ setOtherVariables(fen)
+ {
+ super.setOtherVariables(fen);
+ const pos = V.ParseFen(fen).position;
+ // NOTE: no need for safety "|| []", because each piece type must be present
+ // (otherwise game is already over!)
+ this.material =
+ {
+ "w":
+ {
+ [V.KING]: pos.match(/K/g).length,
+ [V.QUEEN]: pos.match(/Q/g).length,
+ [V.ROOK]: pos.match(/R/g).length,
+ [V.KNIGHT]: pos.match(/N/g).length,
+ [V.BISHOP]: pos.match(/B/g).length,
+ [V.PAWN]: pos.match(/P/g).length
+ },
+ "b":
+ {
+ [V.KING]: pos.match(/k/g).length,
+ [V.QUEEN]: pos.match(/q/g).length,
+ [V.ROOK]: pos.match(/r/g).length,
+ [V.KNIGHT]: pos.match(/n/g).length,
+ [V.BISHOP]: pos.match(/b/g).length,
+ [V.PAWN]: pos.match(/p/g).length
+ }
+ };
+ }
+
+ getPotentialPawnMoves([x,y])
+ {
+ let moves = super.getPotentialPawnMoves([x,y]);
+ // Add potential promotions into king
+ const color = this.turn;
+ const shift = (color == "w" ? -1 : 1);
+ const lastRank = (color == "w" ? 0 : V.size.x-1);
+
+ if (x+shift == lastRank)
+ {
+ // Normal move
+ if (this.board[x+shift][y] == V.EMPTY)
+ moves.push(this.getBasicMove([x,y], [x+shift,y], {c:color,p:V.KING}));
+ // Captures
+ if (y>0 && this.board[x+shift][y-1] != V.EMPTY
+ && this.canTake([x,y], [x+shift,y-1]))
+ {
+ moves.push(this.getBasicMove([x,y], [x+shift,y-1], {c:color,p:V.KING}));
+ }
+ if (y<V.size.y-1 && this.board[x+shift][y+1] != V.EMPTY
+ && this.canTake([x,y], [x+shift,y+1]))
+ {
+ moves.push(this.getBasicMove([x,y], [x+shift,y+1], {c:color,p:V.KING}));
+ }
+ }
+
+ return moves;
+ }
+
+ // TODO: verify this assertion
+ atLeastOneMove()
+ {
+ return true; //always at least one possible move
+ }
+
+ underCheck(color)
+ {
+ return false; //there is no check
+ }
+
+ getCheckSquares(color)
+ {
+ return [];
+ }
+
+ updateVariables(move)
+ {
+ super.updateVariables(move);
+ // Treat the promotion case: (not the capture part)
+ if (move.appear[0].p != move.vanish[0].p)
+ {
+ this.material[move.appear[0].c][move.appear[0].p]++;
+ this.material[move.appear[0].c][V.PAWN]--;
+ }
+ if (move.vanish.length==2 && move.appear.length==1) //capture
+ this.material[move.vanish[1].c][move.vanish[1].p]--;
+ }
+
+ unupdateVariables(move)
+ {
+ super.unupdateVariables(move);
+ if (move.appear[0].p != move.vanish[0].p)
+ {
+ this.material[move.appear[0].c][move.appear[0].p]--;
+ this.material[move.appear[0].c][V.PAWN]++;
+ }
+ if (move.vanish.length==2 && move.appear.length==1)
+ this.material[move.vanish[1].c][move.vanish[1].p]++;
+ }
+
+ checkGameOver()
+ {
+ if (this.checkRepetition())
+ return "1/2";
+
+ if (this.atLeastOneMove()) // game not over?
+ {
+ const color = this.turn;
+ if (Object.keys(this.material[color]).some(
+ p => { return this.material[color][p] == 0; }))
+ {
+ return this.checkGameEnd();
+ }
+ return "*";
+ }
+
+ return this.checkGameEnd(); //NOTE: currently unreachable...
+ }
+
+ checkGameEnd()
+ {
+ return (this.turn == "w" ? "0-1" : "1-0");
+ }
+
+ evalPosition()
+ {
+ const color = this.turn;
+ if (Object.keys(this.material[color]).some(
+ p => { return this.material[color][p] == 0; }))
+ {
+ // Very negative (resp. positive) if white (reps. black) pieces set is incomplete
+ return (color=="w"?-1:1) * V.INFINITY;
+ }
+ return super.evalPosition();
+ }
+}