webpack/lib/Watching.js

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

const Stats = require("./Stats");

class Watching {
	constructor(compiler, watchOptions, handler) {
		this.startTime = null;
		this.invalid = false;
		this.handler = handler;
		this.callbacks = [];
		this.closed = false;
		if(typeof watchOptions === "number") {
			this.watchOptions = {
				aggregateTimeout: watchOptions
			};
		} else if(watchOptions && typeof watchOptions === "object") {
			this.watchOptions = Object.assign({}, watchOptions);
		} else {
			this.watchOptions = {};
		}
		this.watchOptions.aggregateTimeout = this.watchOptions.aggregateTimeout || 200;
		this.compiler = compiler;
		this.running = true;
		this.compiler.readRecords(err => {
			if(err) return this._done(err);

			this._go();
		});
	}

	_go() {
		this.startTime = Date.now();
		this.running = true;
		this.invalid = false;
		this.compiler.hooks.watchRun.callAsync(this.compiler, err => {
			if(err) return this._done(err);
			const onCompiled = (err, compilation) => {
				if(err) return this._done(err);
				if(this.invalid) return this._done();

				if(this.compiler.hooks.shouldEmit.call(compilation) === false) {
					return this._done(null, compilation);
				}

				this.compiler.emitAssets(compilation, err => {
					if(err) return this._done(err);
					if(this.invalid) return this._done();

					this.compiler.emitRecords(err => {
						if(err) return this._done(err);

						if(compilation.hooks.needAdditionalPass.call()) {
							compilation.needAdditionalPass = true;

							const stats = new Stats(compilation);
							stats.startTime = this.startTime;
							stats.endTime = Date.now();
							this.compiler.hooks.done.call(stats);

							this.compiler.hooks.additionalPass.callAsync(err => {
								if(err) return this._done(err);
								this.compiler.compile(onCompiled);
							});
							return;
						}
						return this._done(null, compilation);
					});
				});
			};
			this.compiler.compile(onCompiled);
		});
	}

	_getStats(compilation) {
		const stats = new Stats(compilation);
		stats.startTime = this.startTime;
		stats.endTime = Date.now();
		return stats;
	}

	_done(err, compilation) {
		this.running = false;
		if(this.invalid) return this._go();

		const stats = compilation ? this._getStats(compilation) : null;
		if(err) {
			this.compiler.hooks.failed.call(err);
			this.handler(err, stats);
			return;
		}

		this.compiler.hooks.done.call(stats);
		this.handler(null, stats);
		if(!this.closed) {
			this.watch(Array.from(compilation.fileDependencies), Array.from(compilation.contextDependencies), Array.from(compilation.missingDependencies));
		}
		this.callbacks.forEach(cb => cb());
		this.callbacks.length = 0;
	}

	watch(files, dirs, missing) {
		this.pausedWatcher = null;
		this.watcher = this.compiler.watchFileSystem.watch(files, dirs, missing, this.startTime, this.watchOptions, (err, filesModified, contextModified, missingModified, fileTimestamps, contextTimestamps) => {
			this.pausedWatcher = this.watcher;
			this.watcher = null;
			if(err) return this.handler(err);

			this.compiler.fileTimestamps = fileTimestamps;
			this.compiler.contextTimestamps = contextTimestamps;
			this.invalidate();
		}, (fileName, changeTime) => {
			this.compiler.hooks.invalid.call(fileName, changeTime);
		});
	}

	invalidate(callback) {
		if(callback) {
			this.callbacks.push(callback);
		}
		if(this.watcher) {
			this.pausedWatcher = this.watcher;
			this.watcher.pause();
			this.watcher = null;
		}
		if(this.running) {
			this.invalid = true;
			return false;
		} else {
			this._go();
		}
	}

	close(callback) {
		if(callback === undefined) callback = () => {};

		this.closed = true;
		if(this.watcher) {
			this.watcher.close();
			this.watcher = null;
		}
		if(this.pausedWatcher) {
			this.pausedWatcher.close();
			this.pausedWatcher = null;
		}
		if(this.running) {
			this.invalid = true;
			this._done = () => {
				this.compiler.hooks.watchClose.call();
				callback();
			};
		} else {
			this.compiler.hooks.watchClose.call();
			callback();
		}
	}
}

module.exports = Watching;