xchess/lib/board.js

Chess Engine

export {Board}

import {Color} from './color.js'
import {Square} from './square.js'
import {Piece, King} from './piece.js'
import {MoveMap} from './move-map.js'
import {fenToBoard, boardToFEN} from './fen.js'
import {boardToHash} from './hash.js'
import {table} from './table.js'
import geo from './geo.js'
import {DeadPositionTest, CheckmateChanceTest} from './dead-position.js'
import {SQUARE_IS_EMPTY, INVALID_BOARD} from './errors.js'
import {IS_EMPTY, IS_STRING, IS_OBJECT, IS_ITERABLE} from './types.js'

class Board {

	#map = new Map();
	#all = new Map();

	constructor(config){
		IS_EMPTY(config) || this.#setAll(config);
	}

	// read

	get size(){
		return this.#map.size;
	}

	keys(){
		return this.#map.keys();
	}

	values(){
		return this.#map.values();
	}

	entries(){
		return this.#map.entries();
	}

	at(x, y){
		return this.#map.get(Square.at(x, y)) ?? null;
	}

	has(square){
		return this.#map.has(Square.from(square));
	}

	get(square){
		return this.#map.get(Square.from(square)) ?? null;
	}

	find(piece){
		return this.#all.get(piece) ?? null;
	}

	contains(piece){
		return this.#all.has(piece);
	}

	// write

	#set(square, piece){
		this.#all.set(piece, square);
		this.#map.set(square, piece);
	}

	#delete(square, piece){
		this.#map.delete(square, piece);
		this.#all.delete(piece, square);
	}

	#setAsMap(iterable){
		const map = new Map();
		const all = new Map();
		for(const [square, piece] of iterable){
			const key = Square.from(square);
			const val = Piece.from(piece);
			map.set(key, val);
			all.set(val, key);
		}
		this.#map = map;
		this.#all = all;
	}

	#setAsObject(boardObject){
		this.#setAsMap(Object.entries(boardObject));
	}

	#setAll(board){
		if(IS_STRING(board))
			this.fen = board;
		else if(IS_OBJECT(board)){
			if(IS_ITERABLE(board))
				this.#setAsMap(board);
			else
				this.#setAsObject(board);
		} else throw INVALID_BOARD(board);
	}

	setAll(board){
		if(IS_EMPTY(board)) this.clear();
		else this.#setAll(board);
	}

	set(square, pieceArg){
		const piece = Piece.from(pieceArg);
		const target = Square.from(square);
		const source = this.find(piece);
		const victim = this.get(target);
		if(victim === piece)
			return {change: false}
		const report = {
			change: true,
			to: target,
		};
		if(source){
			report.from = source;
			report.moved = piece;
			this.#map.delete(source);
		} else {
			report.inserted = piece;
		}
		if(victim){
			this.#all.delete(victim);
			report.deleted = victim;
		}
		this.#set(target, piece);
		return report;
	}

	move(from, to){
		const target = Square.from(to);
		const source = Square.from(from);
		const piece = this.get(source);
		const victim = this.get(target);
		if(!piece)
			throw SQUARE_IS_EMPTY(source);
		if(target === source)
			return {change: false};
		const report = {
			change: true,
			from: source,
			to: target,
			moved: piece,
		};
		if(victim){
			report.deleted = victim;
			this.#all.delete(victim);
		}
		this.#map.delete(source);
		this.#set(target, piece);
		return report;
	}

	delete(square){
		const target = Square.from(square);
		const piece = this.get(target);
		if(piece){
			this.#delete(target, piece);
			return {change: true, from: target, deleted: piece};
		}	return {change: false};
	}

	clear(){
		const count = this.size;
		this.#map.clear();
		this.#all.clear();
		return count;
	}

	// geo

	crossT(piece, square){
		return geo.crossT(piece, square, this);
	}

	crossX(piece, square){
		return geo.crossX(piece, square, this);
	}

	crossAny(piece, square){
		return geo.crossAny(piece, square, this);
	}

	isNear(piece, square){
		return geo.isNear(piece, square, this);
	}

	isL(piece, square){
		return geo.isL(piece, square, this);
	}

	traceT(piece){
		return geo.traceT(piece, this);
	}

	traceX(piece){
		return geo.traceX(piece, this);
	}

	traceAll(piece){
		return geo.traceAll(piece, this);
	}

	L(piece){
		return geo.L(piece, this);
	}

	near(piece){
		return geo.near(piece, this);
	}

	// colors

	* #like(color){
		for(const piece of this.values())
			if(piece.color === color)
				yield piece;
	}

	like(color){
		return [... this.#like(Color.from(color))];
	}

	not(color){
		return [... this.#like(Color.invert(color))];
	}

	// rules

	testAt(square, color){
		const at = Square.from(square);
		const pieces = this.not(color);
		for(const piece of pieces)
			if(piece.test(square, this))
				return true;
		return false;
	}

	testAllAt(square, color){
		const at = Square.from(square);
		const pieces = this.not(color);
		const all = [];
		for(const piece of pieces)
			if(piece.test(square, this))
				all.push(piece);
		return all;
	}

	test(piece){
		const square = this.find(piece);
		if(square)
			return this.testAt(square, piece.color);
		return false;
	}

	testAll(piece){
		const square = this.find(piece);
		if(square)
			return this.testAllAt(square, piece.color);
		return [];
	}

	check(color){
		const pieces = this.like(color);
		for(const piece of pieces){
			if((piece instanceof King) && this.test(piece))
				return piece;
		} return false;
	}

	isDeadPosition(){
		return DeadPositionTest(this);
	}

	isCheckmateChance(color){
		return CheckmateChanceTest(this, Color.from(color));
	}

	// moves

	* #moves(context){
		const pieces = this.like(context.color);
		for(const piece of pieces)
			yield * piece.moves(context);
	}

	* #allMoves(context){
		const pieces = this.like(context.color);
		for(const piece of pieces)
			yield * piece.allMoves(context);
	}

	moves(context){
		return new MoveMap(this.#moves(context));
	}

	allMoves(context){
		return new MoveMap(this.#allMoves(context));
	}

	// I/O

	[Symbol.iterator](){
		return this.#map.entries();
	}

	toString(){
		return this.fen;
	}

	hash(){
		return boardToHash(this);
	}

	get fen(){
		return boardToFEN(this);
	}

	set fen(fen){
		const board = fenToBoard(fen);
		this.clear();
		for(const [square, piece] of board)
			this.#set(square, piece);
	}

	toJSON(){
		const board = {};
		for(const [square, piece] of this)
			board[square] = piece.toJSON();
		return board;
	}

	text(opts){
		return table(this, opts);
	}

	log(opts){
		console.log(this.text(opts));
	}
}