xchess/lib/move-map.js

Chess Engine

export {MoveMap, EmptyMoveMap}

import {ParseMove} from './move-parser.js'
import {ComputeDisambiguationLevels} from './move-disambiguator.js'
import {IS_INTEGER, IS_STRING} from './types.js'
import {INVALID_MOVE_VALUE, AMBIGUOUS_MOVE} from './errors.js'

class MoveMap {

	#list;

	constructor(moves){
		this.#list = new Set(moves);
		this.#computeDisambiguationLevels();
	}

	[Symbol.iterator](){
		return this.#list.values();
	}

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

	stat(){
		const count = this.size;
		const pieces = new Set();
		const squares = new Set();
		const captures = new Set();
		let captureCount = 0;
		for(const move of this){
			pieces.add(move.target);
			squares.add(move.to);
			if(move.capture){
				captures.add(move.capture);
				captureCount ++;
			}
		}
		const fatality = captureCount / count;
		return {count, captureCount, fatality, pieces, squares, captures}; 
	}

	#computeDisambiguationLevels(){
		ComputeDisambiguationLevels(this);
	}

	#search(moveArg){
		const all = [];
		const MoveCond = ParseMove(moveArg);
		for(const move of this){
			const fixMove = move.resolve(MoveCond);
			if(fixMove) all.push(fixMove);
		}
		return all;
	}

	#test(moveArg){
		const MoveCond = ParseMove(moveArg);
		for(const move of this)
			if(move.match(MoveCond))
				return true;
		return false;
	}

	#fromCode(code){
		for(const move of this)
			if(move.code === code)
				return move;
		return null;
	}

	#filterByCode(code){
		const all = [];
		for(const move of this)
			if(move.code === code)
				all.push(move);
		return all;
	}

	#hasCode(code){
		for(const move of this)
			if(move.code === code)
				return true;
		return false;
	}

	of(piece){
		const moves = [];
		for(const move of this)
			if(move.target === piece)
				moves.push(move);
		return moves;
	}

	has(moveArg){
		if(this.#list.has(moveArg))
			return true;
		if(IS_INTEGER(moveArg))
			return this.#hasCode(moveArg);
		if(IS_STRING(moveArg))
			return this.#test(moveArg);
		return false;
	}

	get(moveArg){
		if(this.#list.has(moveArg))
			return moveArg;
		if(IS_INTEGER(moveArg))
			return this.#fromCode(moveArg);
		const [move, ... rest] = this.#search(String(moveArg));
		if(move){
			if(rest.length > 0)
				throw AMBIGUOUS_MOVE(moveArg);
			return move;
		}	return null;
		throw INVALID_MOVE_VALUE(moveArg);
	}

	getAll(moveArg){
		if(this.#list.has(moveArg))
			return [moveArg];
		if(IS_INTEGER(moveArg))
			return this.#filterByCode(moveArg);
		if(IS_STRING(moveArg))
			return this.#search(moveArg);
	}
}

const EmptyMoveMap = new MoveMap();