webpack/lib/ContextModuleFactory.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 asyncLib = require("neo-async");
const path = require("path");

const {
	Tapable,
	AsyncSeriesWaterfallHook,
	SyncWaterfallHook
} = require("tapable");
const ContextModule = require("./ContextModule");
const ContextElementDependency = require("./dependencies/ContextElementDependency");

/** @typedef {import("./Module")} Module */

const EMPTY_RESOLVE_OPTIONS = {};

module.exports = class ContextModuleFactory extends Tapable {
	constructor(resolverFactory) {
		super();
		this.hooks = {
			/** @type {AsyncSeriesWaterfallHook<TODO>} */
			beforeResolve: new AsyncSeriesWaterfallHook(["data"]),
			/** @type {AsyncSeriesWaterfallHook<TODO>} */
			afterResolve: new AsyncSeriesWaterfallHook(["data"]),
			/** @type {SyncWaterfallHook<string[]>} */
			contextModuleFiles: new SyncWaterfallHook(["files"]),
			/** @type {SyncWaterfallHook<TODO[]>} */
			alternatives: new AsyncSeriesWaterfallHook(["modules"])
		};
		this._pluginCompat.tap("ContextModuleFactory", options => {
			switch (options.name) {
				case "before-resolve":
				case "after-resolve":
				case "alternatives":
					options.async = true;
					break;
			}
		});
		this.resolverFactory = resolverFactory;
	}

	create(data, callback) {
		const context = data.context;
		const dependencies = data.dependencies;
		const resolveOptions = data.resolveOptions;
		const dependency = dependencies[0];
		this.hooks.beforeResolve.callAsync(
			Object.assign(
				{
					context: context,
					dependencies: dependencies,
					resolveOptions
				},
				dependency.options
			),
			(err, beforeResolveResult) => {
				if (err) return callback(err);

				// Ignored
				if (!beforeResolveResult) return callback();

				const context = beforeResolveResult.context;
				const request = beforeResolveResult.request;
				const resolveOptions = beforeResolveResult.resolveOptions;

				let loaders,
					resource,
					loadersPrefix = "";
				const idx = request.lastIndexOf("!");
				if (idx >= 0) {
					let loadersRequest = request.substr(0, idx + 1);
					let i;
					for (
						i = 0;
						i < loadersRequest.length && loadersRequest[i] === "!";
						i++
					) {
						loadersPrefix += "!";
					}
					loadersRequest = loadersRequest
						.substr(i)
						.replace(/!+$/, "")
						.replace(/!!+/g, "!");
					if (loadersRequest === "") {
						loaders = [];
					} else {
						loaders = loadersRequest.split("!");
					}
					resource = request.substr(idx + 1);
				} else {
					loaders = [];
					resource = request;
				}

				const contextResolver = this.resolverFactory.get(
					"context",
					resolveOptions || EMPTY_RESOLVE_OPTIONS
				);
				const loaderResolver = this.resolverFactory.get(
					"loader",
					EMPTY_RESOLVE_OPTIONS
				);

				asyncLib.parallel(
					[
						callback => {
							contextResolver.resolve(
								{},
								context,
								resource,
								{},
								(err, result) => {
									if (err) return callback(err);
									callback(null, result);
								}
							);
						},
						callback => {
							asyncLib.map(
								loaders,
								(loader, callback) => {
									loaderResolver.resolve(
										{},
										context,
										loader,
										{},
										(err, result) => {
											if (err) return callback(err);
											callback(null, result);
										}
									);
								},
								callback
							);
						}
					],
					(err, result) => {
						if (err) return callback(err);

						this.hooks.afterResolve.callAsync(
							Object.assign(
								{
									addon:
										loadersPrefix +
										result[1].join("!") +
										(result[1].length > 0 ? "!" : ""),
									resource: result[0],
									resolveDependencies: this.resolveDependencies.bind(this)
								},
								beforeResolveResult
							),
							(err, result) => {
								if (err) return callback(err);

								// Ignored
								if (!result) return callback();

								return callback(
									null,
									new ContextModule(result.resolveDependencies, result)
								);
							}
						);
					}
				);
			}
		);
	}

	resolveDependencies(fs, options, callback) {
		const cmf = this;
		let resource = options.resource;
		let resourceQuery = options.resourceQuery;
		let recursive = options.recursive;
		let regExp = options.regExp;
		let include = options.include;
		let exclude = options.exclude;
		if (!regExp || !resource) return callback(null, []);

		const addDirectory = (directory, callback) => {
			fs.readdir(directory, (err, files) => {
				if (err) return callback(err);
				files = cmf.hooks.contextModuleFiles.call(files);
				if (!files || files.length === 0) return callback(null, []);
				asyncLib.map(
					files.filter(p => p.indexOf(".") !== 0),
					(segment, callback) => {
						const subResource = path.join(directory, segment);

						if (!exclude || !subResource.match(exclude)) {
							fs.stat(subResource, (err, stat) => {
								if (err) {
									if (err.code === "ENOENT") {
										// ENOENT is ok here because the file may have been deleted between
										// the readdir and stat calls.
										return callback();
									} else {
										return callback(err);
									}
								}

								if (stat.isDirectory()) {
									if (!recursive) return callback();
									addDirectory.call(this, subResource, callback);
								} else if (
									stat.isFile() &&
									(!include || subResource.match(include))
								) {
									const obj = {
										context: resource,
										request:
											"." +
											subResource.substr(resource.length).replace(/\\/g, "/")
									};

									this.hooks.alternatives.callAsync(
										[obj],
										(err, alternatives) => {
											if (err) return callback(err);
											alternatives = alternatives
												.filter(obj => regExp.test(obj.request))
												.map(obj => {
													const dep = new ContextElementDependency(
														obj.request + resourceQuery,
														obj.request
													);
													dep.optional = true;
													return dep;
												});
											callback(null, alternatives);
										}
									);
								} else {
									callback();
								}
							});
						} else {
							callback();
						}
					},
					(err, result) => {
						if (err) return callback(err);

						if (!result) return callback(null, []);

						callback(
							null,
							result.filter(Boolean).reduce((a, i) => a.concat(i), [])
						);
					}
				);
			});
		};

		addDirectory(resource, callback);
	}
};