claude (duplicate_chess)
33 lines
1.2 KiB
TypeScript
33 lines
1.2 KiB
TypeScript
import type { DuplicateGame } from './game';
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import type { GhostMarker, BoardId, Color, Square } from './types';
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import { PLAYERS, PLAYER_BOARDS, PLAYER_COLOR } from './boards';
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/** Squares occupied by a piece of `color` on `board`. */
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function colorSquares(game: DuplicateGame, board: BoardId, color: Color): Set<Square> {
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const set = new Set<Square>();
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for (const row of game.boards[board].board()) {
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for (const cell of row) {
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if (cell && cell.color === color) set.add(cell.square);
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}
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}
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return set;
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}
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/**
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* Ghosts across all four players. A player's non-ghost pieces always occupy
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* identical squares on both their boards (they move in lockstep), so a piece is
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* a ghost iff the player's other board has no same-colour piece on that square.
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*/
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export function ghosts(game: DuplicateGame): GhostMarker[] {
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const markers: GhostMarker[] = [];
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for (const player of PLAYERS) {
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const [a, b] = PLAYER_BOARDS[player];
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const color = PLAYER_COLOR[player];
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const sqA = colorSquares(game, a, color);
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const sqB = colorSquares(game, b, color);
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for (const sq of sqA) if (!sqB.has(sq)) markers.push({ board: a, square: sq });
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for (const sq of sqB) if (!sqA.has(sq)) markers.push({ board: b, square: sq });
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}
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return markers;
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}
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