webpack/lib/util/TupleSet.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/

"use strict";

/**
 * @template K
 * @template V
 * @typedef {Map<K, InnerMap<K, V> | Set<V>>} InnerMap
 */

/**
 * @template T
 * @template V
 */
class TupleSet {
	/**
	 * @param {Iterable<[T, V, ...EXPECTED_ANY]>=} init init
	 */
	constructor(init) {
		/** @type {InnerMap<T, V>} */
		this._map = new Map();
		this.size = 0;
		if (init) {
			for (const tuple of init) {
				this.add(...tuple);
			}
		}
	}

	/**
	 * @param {[T, V, ...EXPECTED_ANY]} args tuple
	 * @returns {void}
	 */
	add(...args) {
		let map = this._map;
		for (let i = 0; i < args.length - 2; i++) {
			const arg = args[i];
			const innerMap = map.get(arg);
			if (innerMap === undefined) {
				map.set(arg, (map = new Map()));
			} else {
				map = /** @type {InnerMap<T, V>} */ (innerMap);
			}
		}

		const beforeLast = args[args.length - 2];
		let set = /** @type {Set<V>} */ (map.get(beforeLast));
		if (set === undefined) {
			map.set(beforeLast, (set = new Set()));
		}

		const last = args[args.length - 1];
		this.size -= set.size;
		set.add(last);
		this.size += set.size;
	}

	/**
	 * @param {[T, V, ...EXPECTED_ANY]} args tuple
	 * @returns {boolean} true, if the tuple is in the Set
	 */
	has(...args) {
		let map = this._map;
		for (let i = 0; i < args.length - 2; i++) {
			const arg = args[i];
			map = /** @type {InnerMap<T, V>} */ (map.get(arg));
			if (map === undefined) {
				return false;
			}
		}

		const beforeLast = args[args.length - 2];
		const set = map.get(beforeLast);
		if (set === undefined) {
			return false;
		}

		const last = args[args.length - 1];
		return set.has(last);
	}

	/**
	 * @param {[T, V, ...EXPECTED_ANY]} args tuple
	 * @returns {void}
	 */
	delete(...args) {
		let map = this._map;
		for (let i = 0; i < args.length - 2; i++) {
			const arg = args[i];
			map = /** @type {InnerMap<T, V>} */ (map.get(arg));
			if (map === undefined) {
				return;
			}
		}

		const beforeLast = args[args.length - 2];
		const set = map.get(beforeLast);
		if (set === undefined) {
			return;
		}

		const last = args[args.length - 1];
		this.size -= set.size;
		set.delete(last);
		this.size += set.size;
	}

	/**
	 * @returns {Iterator<[T, V, ...EXPECTED_ANY]>} iterator
	 */
	[Symbol.iterator]() {
		// This is difficult to type because we can have a map inside a map inside a map, etc. where the end is a set (each key is an argument)
		// But in basic use we only have 2 arguments in our methods, so we have `Map<K, Set<V>>`
		/** @type {MapIterator<[T, InnerMap<T, V> | Set<V>]>[]} */
		const iteratorStack = [];
		/** @type {[T?, V?, ...EXPECTED_ANY]} */
		const tuple = [];
		/** @type {SetIterator<V> | undefined} */
		let currentSetIterator;

		/**
		 * @param {MapIterator<[T, InnerMap<T, V> | Set<V>]>} it iterator
		 * @returns {boolean} result
		 */
		const next = it => {
			const result = it.next();
			if (result.done) {
				if (iteratorStack.length === 0) return false;
				tuple.pop();
				return next(
					/** @type {MapIterator<[T, InnerMap<T, V> | Set<V>]>} */
					(iteratorStack.pop())
				);
			}
			const [key, value] = result.value;
			iteratorStack.push(it);
			tuple.push(key);
			if (value instanceof Set) {
				currentSetIterator = value[Symbol.iterator]();
				return true;
			}
			return next(value[Symbol.iterator]());
		};

		next(this._map[Symbol.iterator]());

		return {
			next() {
				while (currentSetIterator) {
					const result = currentSetIterator.next();
					if (result.done) {
						tuple.pop();
						if (
							!next(
								/** @type {MapIterator<[T, InnerMap<T, V> | Set<V>]>} */
								(iteratorStack.pop())
							)
						) {
							currentSetIterator = undefined;
						}
					} else {
						return {
							done: false,
							value:
								/** @type {[T, V, ...EXPECTED_ANY]} */
								(tuple.concat(result.value))
						};
					}
				}
				return { done: true, value: undefined };
			}
		};
	}
}

module.exports = TupleSet;