webpack/lib/util/LazySet.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support 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";

const makeSerializable = require("./makeSerializable.js");

/**
 * @template T
 * @param {Set<T>} targetSet set where items should be added
 * @param {Set<Iterable<T>>} toMerge iterables to be merged
 * @returns {void}
 */
const merge = (targetSet, toMerge) => {
	for (const set of toMerge) {
		for (const item of set) {
			targetSet.add(item);
		}
	}
};

/**
 * @template T
 * @param {Set<Iterable<T>>} targetSet set where iterables should be added
 * @param {Array<LazySet<T>>} toDeepMerge lazy sets to be flattened
 * @returns {void}
 */
const flatten = (targetSet, toDeepMerge) => {
	for (const set of toDeepMerge) {
		if (set._set.size > 0) targetSet.add(set._set);
		if (set._needMerge) {
			for (const mergedSet of set._toMerge) {
				targetSet.add(mergedSet);
			}
			flatten(targetSet, set._toDeepMerge);
		}
	}
};

/**
 * Like Set but with an addAll method to eventually add items from another iterable.
 * Access methods make sure that all delayed operations are executed.
 * Iteration methods deopts to normal Set performance until clear is called again (because of the chance of modifications during iteration).
 * @template T
 */
class LazySet {
	/**
	 * @param {Iterable<T>=} iterable init iterable
	 */
	constructor(iterable) {
		/** @type {Set<T>} */
		this._set = new Set(iterable);
		/** @type {Set<Iterable<T>>} */
		this._toMerge = new Set();
		/** @type {Array<LazySet<T>>} */
		this._toDeepMerge = [];
		this._needMerge = false;
		this._deopt = false;
	}

	_flatten() {
		flatten(this._toMerge, this._toDeepMerge);
		this._toDeepMerge.length = 0;
	}

	_merge() {
		this._flatten();
		merge(this._set, this._toMerge);
		this._toMerge.clear();
		this._needMerge = false;
	}

	_isEmpty() {
		return (
			this._set.size === 0 &&
			this._toMerge.size === 0 &&
			this._toDeepMerge.length === 0
		);
	}

	get size() {
		if (this._needMerge) this._merge();
		return this._set.size;
	}

	/**
	 * @param {T} item an item
	 * @returns {this} itself
	 */
	add(item) {
		this._set.add(item);
		return this;
	}

	/**
	 * @param {Iterable<T> | LazySet<T>} iterable a immutable iterable or another immutable LazySet which will eventually be merged into the Set
	 * @returns {this} itself
	 */
	addAll(iterable) {
		if (this._deopt) {
			const _set = this._set;
			for (const item of iterable) {
				_set.add(item);
			}
		} else {
			if (iterable instanceof LazySet) {
				if (iterable._isEmpty()) return this;
				this._toDeepMerge.push(iterable);
				this._needMerge = true;
				if (this._toDeepMerge.length > 100000) {
					this._flatten();
				}
			} else {
				this._toMerge.add(iterable);
				this._needMerge = true;
			}
			if (this._toMerge.size > 100000) this._merge();
		}
		return this;
	}

	clear() {
		this._set.clear();
		this._toMerge.clear();
		this._toDeepMerge.length = 0;
		this._needMerge = false;
		this._deopt = false;
	}

	/**
	 * @param {T} value an item
	 * @returns {boolean} true, if the value was in the Set before
	 */
	delete(value) {
		if (this._needMerge) this._merge();
		return this._set.delete(value);
	}

	entries() {
		this._deopt = true;
		if (this._needMerge) this._merge();
		return this._set.entries();
	}

	/**
	 * @param {function(T, T, Set<T>): void} callbackFn function called for each entry
	 * @param {any} thisArg this argument for the callbackFn
	 * @returns {void}
	 */
	forEach(callbackFn, thisArg) {
		this._deopt = true;
		if (this._needMerge) this._merge();
		this._set.forEach(callbackFn, thisArg);
	}

	/**
	 * @param {T} item an item
	 * @returns {boolean} true, when the item is in the Set
	 */
	has(item) {
		if (this._needMerge) this._merge();
		return this._set.has(item);
	}

	keys() {
		this._deopt = true;
		if (this._needMerge) this._merge();
		return this._set.keys();
	}

	values() {
		this._deopt = true;
		if (this._needMerge) this._merge();
		return this._set.values();
	}

	[Symbol.iterator]() {
		this._deopt = true;
		if (this._needMerge) this._merge();
		return this._set[Symbol.iterator]();
	}

	/* istanbul ignore next */
	get [Symbol.toStringTag]() {
		return "LazySet";
	}

	serialize({ write }) {
		if (this._needMerge) this._merge();
		write(this._set.size);
		for (const item of this._set) write(item);
	}

	static deserialize({ read }) {
		const count = read();
		const items = [];
		for (let i = 0; i < count; i++) {
			items.push(read());
		}
		return new LazySet(items);
	}
}

makeSerializable(LazySet, "webpack/lib/util/LazySet");

module.exports = LazySet;