webpack/lib/node/NodeWatchFileSystem.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 Watchpack = require("watchpack");

/** @typedef {import("../../declarations/WebpackOptions").WatchOptions} WatchOptions */
/** @typedef {import("../FileSystemInfo").FileSystemInfoEntry} FileSystemInfoEntry */
/** @typedef {import("../util/fs").WatchFileSystem} WatchFileSystem */
/** @typedef {import("../util/fs").WatchMethod} WatchMethod */
/** @typedef {import("../util/fs").Watcher} Watcher */

class NodeWatchFileSystem {
	constructor(inputFileSystem) {
		this.inputFileSystem = inputFileSystem;
		this.watcherOptions = {
			aggregateTimeout: 0
		};
		this.watcher = new Watchpack(this.watcherOptions);
	}

	/**
	 * @param {Iterable<string>} files watched files
	 * @param {Iterable<string>} directories watched directories
	 * @param {Iterable<string>} missing watched exitance entries
	 * @param {number} startTime timestamp of start time
	 * @param {WatchOptions} options options object
	 * @param {function(Error=, Map<string, FileSystemInfoEntry>, Map<string, FileSystemInfoEntry>, Set<string>, Set<string>): void} callback aggregated callback
	 * @param {function(string, number): void} callbackUndelayed callback when the first change was detected
	 * @returns {Watcher} a watcher
	 */
	watch(
		files,
		directories,
		missing,
		startTime,
		options,
		callback,
		callbackUndelayed
	) {
		if (!files || typeof files[Symbol.iterator] !== "function") {
			throw new Error("Invalid arguments: 'files'");
		}
		if (!directories || typeof directories[Symbol.iterator] !== "function") {
			throw new Error("Invalid arguments: 'directories'");
		}
		if (!missing || typeof missing[Symbol.iterator] !== "function") {
			throw new Error("Invalid arguments: 'missing'");
		}
		if (typeof callback !== "function") {
			throw new Error("Invalid arguments: 'callback'");
		}
		if (typeof startTime !== "number" && startTime) {
			throw new Error("Invalid arguments: 'startTime'");
		}
		if (typeof options !== "object") {
			throw new Error("Invalid arguments: 'options'");
		}
		if (typeof callbackUndelayed !== "function" && callbackUndelayed) {
			throw new Error("Invalid arguments: 'callbackUndelayed'");
		}
		const oldWatcher = this.watcher;
		this.watcher = new Watchpack(options);

		if (callbackUndelayed) {
			this.watcher.once("change", callbackUndelayed);
		}
		this.watcher.once("aggregated", (changes, removals) => {
			if (this.inputFileSystem && this.inputFileSystem.purge) {
				for (const item of changes) {
					this.inputFileSystem.purge(item);
				}
				for (const item of removals) {
					this.inputFileSystem.purge(item);
				}
			}
			const times = this.watcher.getTimeInfoEntries();
			callback(null, times, times, changes, removals);
		});

		this.watcher.watch({ files, directories, missing, startTime });

		if (oldWatcher) {
			oldWatcher.close();
		}
		return {
			close: () => {
				if (this.watcher) {
					this.watcher.close();
					this.watcher = null;
				}
			},
			pause: () => {
				if (this.watcher) {
					this.watcher.pause();
				}
			},
			getFileTimeInfoEntries: () => {
				if (this.watcher) {
					return this.watcher.getTimeInfoEntries();
				} else {
					return new Map();
				}
			},
			getContextTimeInfoEntries: () => {
				if (this.watcher) {
					return this.watcher.getTimeInfoEntries();
				} else {
					return new Map();
				}
			}
		};
	}
}

module.exports = NodeWatchFileSystem;