xchess/lib/rank.js

Chess Engine

export {Rank, ranks}

import {INVALID_RANK} from './errors.js'
import {ConstNumberObject} from './ansi-style.js'
import {inspect} from './inspect.js'

const size = 8;
const ranks = [];
const map = new Map();

function nameAt(y){
	return String(8 - y);
}

function iccfAt(y){
	return 8 - y;
}

function rank(value){
	const rank = map.get(value);
	if(rank)
		return rank;
	throw INVALID_RANK(value);
}

class Rank {

	static from(value){
		return rank(value);
	}

	static is(value){
		return map.has(value);
	}

	static all(){
		return ranks;
	}

	static reverse(){
		return ReverseRanks;
	}

	#y;
	#iccf;
	#name;
	#squares = [];

	constructor(y){
		this.#y = y;
		this.#iccf = iccfAt(y);
		this.#name = nameAt(y);
	}

	get y(){
		return this.#y;
	}

	get iccf(){
		return this.#iccf;
	}

	get name(){
		return this.#name;
	}

	get squares(){
		return this.#squares;
	}

	toString(){
		return this.name;
	}

	valueOf(){
		return this.index;
	}

	[inspect.custom](depth, opts){
		return ConstNumberObject(`[Rank ${this.name}]`);
	}
}

// generate all

while(ranks.length < size){
	const index = ranks.length;
	const rank = new Rank(index);
	ranks.push(rank);
	map.set(rank, rank);
	map.set(rank.y, rank);
	map.set(rank.name, rank);
}

const ReverseRanks = [... ranks];
ReverseRanks.reverse();

Object.freeze(ranks);
Object.freeze(ReverseRanks);