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add more precise disambiguation of pieces in history

This commit is contained in:
Jesse D. McDonald 2020-03-15 14:30:33 -05:00
parent 5011cfed8c
commit 0769d7579b
1 changed files with 41 additions and 16 deletions
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55
js/chess.js
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@ -79,6 +79,24 @@ function boardPut(board, where, side, piece){
board[side][row] = prefix + piece + suffix;
}
function movedFrom(board){
if (!board || !board.move || !board.move.from) {
return null;
} else if (board.move.from === 'phantom') {
return board.prior.phantom.from;
} else {
return board.move.from;
}
}
function movedTo(board){
if (!board || !board.move || !board.move.to) {
return null;
} else {
return board.move.to;
}
}
function countMoves(board) {
let n = 0;
while (board && board.prior) {
@ -145,6 +163,7 @@ function hasMoved(board, side, where){
function legalMoves(board, side, type, from, canCapture){
if (board.move && board.move.took === 'k') {
/* checkmate, the game is over */
return [];
}
@ -236,11 +255,8 @@ function legalMoves(board, side, type, from, canCapture){
if (otherBoard && otherBoard.move) {
const move = otherBoard.move;
if (move.side[0] !== side[0] && move.type === 'p') {
const from =
(move.from === 'phantom') ?
otherBoard.prior.phantom.from :
move.from;
if (from[0] === there[0] && from[1] === forward2[1]) {
const from = movedFrom(otherBoard);
if (from && from[0] === there[0] && from[1] === forward2[1]) {
/* en passant */
legals.push(there);
}
@ -324,7 +340,7 @@ function movePiece(priorBoard, side, from, to){
if (otherBoard && otherBoard.move) {
const move = otherBoard.move;
if (move.type === 'p' && move.to[0] === to[0] && move.to[1] === actuallyFrom[1]) {
const moveFrom = (move.from === 'phantom') ? otherBoard.prior.phantom.from : move.from;
const moveFrom = movedFrom(otherBoard);
if (move.side[0] === other[0] && moveFrom[1] != to[1]) {
board.move.en_passant = true;
board.move.took = 'p';
@ -372,17 +388,24 @@ function movePiece(priorBoard, side, from, to){
return board;
}
function findPieces(board, side, type){
function findPieces(board, side, type, alongside){
let pieces = [];
const other = otherSide(side);
if (board.phantom && board.phantom.type === type + side[0]) {
pieces.push(board.phantom.from);
}
for (const row of "12345678") {
for (const column of "abcdefgh") {
const here = column + row;
if (boardGet(board, here, side) === type) {
if (!alongside || boardGet(board, here, other) === alongside) {
pieces.push(here);
}
}
}
}
return pieces;
}
@ -437,8 +460,10 @@ function renderHistory(currentBoard) {
piece = move.type === 'p' ? '' : move.type.toUpperCase();
}
if (move.from !== 'phantom') {
const sameKind = findPieces(board.prior, move.side, move.type);
const from = movedFrom(board);
if (move.from !== 'phantom' || from !== movedTo(board.prior)) {
const sameKind = findPieces(board.prior, move.side, move.type, move.alongside || ' ');
const legalFrom = [];
let sameFile = 0; /* column / letter */
let sameRank = 0; /* row / number */
@ -447,24 +472,24 @@ function renderHistory(currentBoard) {
if (legalMoves(board.prior, move.side, move.type, where, true).includes(move.to)) {
legalFrom.push(where);
if (where[0] === move.from[0]) {
if (where[0] === from[0]) {
sameFile += 1;
}
if (where[1] === move.from[1]) {
if (where[1] === from[1]) {
sameRank += 1;
}
}
}
if (legalFrom.length !== 1) {
if (legalFrom.length !== 1 || move.en_passant || (move.type === 'p' && move.took)) {
/* append file, rank, or both to disambiguate */
if (sameFile === 1) {
piece += move.from[0];
piece += from[0];
} else if (sameRank === 1) {
piece += move.from[1];
piece += from[1];
} else {
piece += move.from;
piece += from;
}
}
}