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");
const objectToMap = require("../util/objectToMap");

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

	watch(files, dirs, missing, startTime, options, callback, callbackUndelayed) {
		if (!Array.isArray(files)) {
			throw new Error("Invalid arguments: 'files'");
		}
		if (!Array.isArray(dirs)) {
			throw new Error("Invalid arguments: 'dirs'");
		}
		if (!Array.isArray(missing)) {
			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);
		}
		const cachedFiles = files;
		const cachedDirs = dirs;
		this.watcher.once("aggregated", (changes, removals) => {
			changes = changes.concat(removals);
			if (this.inputFileSystem && this.inputFileSystem.purge) {
				this.inputFileSystem.purge(changes);
			}
			const times = objectToMap(this.watcher.getTimes());
			files = new Set(files);
			dirs = new Set(dirs);
			missing = new Set(missing);
			removals = new Set(removals.filter(file => files.has(file)));
			callback(
				null,
				changes.filter(file => files.has(file)).sort(),
				changes.filter(file => dirs.has(file)).sort(),
				changes.filter(file => missing.has(file)).sort(),
				times,
				times,
				removals
			);
		});

		this.watcher.watch(
			cachedFiles.concat(missing),
			cachedDirs.concat(missing),
			startTime
		);

		if (oldWatcher) {
			oldWatcher.close();
		}
		return {
			close: () => {
				if (this.watcher) {
					this.watcher.close();
					this.watcher = null;
				}
			},
			pause: () => {
				if (this.watcher) {
					this.watcher.pause();
				}
			},
			getFileTimestamps: () => {
				if (this.watcher) {
					return objectToMap(this.watcher.getTimes());
				} else {
					return new Map();
				}
			},
			getContextTimestamps: () => {
				if (this.watcher) {
					return objectToMap(this.watcher.getTimes());
				} else {
					return new Map();
				}
			}
		};
	}
}

module.exports = NodeWatchFileSystem;