webpack/lib/ResolverFactory.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 { Tapable, HookMap, SyncHook, SyncWaterfallHook } = require("tapable");
const Factory = require("enhanced-resolve").ResolverFactory;
const { cachedCleverMerge } = require("./util/cleverMerge");

/** @typedef {import("enhanced-resolve").Resolver} Resolver */

const EMTPY_RESOLVE_OPTIONS = {};

module.exports = class ResolverFactory extends Tapable {
	constructor() {
		super();
		this.hooks = {
			resolveOptions: new HookMap(
				() => new SyncWaterfallHook(["resolveOptions"])
			),
			resolver: new HookMap(() => new SyncHook(["resolver", "resolveOptions"]))
		};
		this._pluginCompat.tap("ResolverFactory", options => {
			let match;
			match = /^resolve-options (.+)$/.exec(options.name);
			if (match) {
				this.hooks.resolveOptions
					.for(match[1])
					.tap(options.fn.name || "unnamed compat plugin", options.fn);
				return true;
			}
			match = /^resolver (.+)$/.exec(options.name);
			if (match) {
				this.hooks.resolver
					.for(match[1])
					.tap(options.fn.name || "unnamed compat plugin", options.fn);
				return true;
			}
		});
		this.cache2 = new Map();
	}

	get(type, resolveOptions) {
		resolveOptions = resolveOptions || EMTPY_RESOLVE_OPTIONS;
		const ident = `${type}|${JSON.stringify(resolveOptions)}`;
		const resolver = this.cache2.get(ident);
		if (resolver) return resolver;
		const newResolver = this._create(type, resolveOptions);
		this.cache2.set(ident, newResolver);
		return newResolver;
	}

	_create(type, resolveOptions) {
		const originalResolveOptions = Object.assign({}, resolveOptions);
		resolveOptions = this.hooks.resolveOptions.for(type).call(resolveOptions);
		const resolver = Factory.createResolver(resolveOptions);
		if (!resolver) {
			throw new Error("No resolver created");
		}
		/** @type {Map<Object, Resolver>} */
		const childCache = new Map();
		resolver.withOptions = options => {
			const cacheEntry = childCache.get(options);
			if (cacheEntry !== undefined) return cacheEntry;
			const mergedOptions = cachedCleverMerge(originalResolveOptions, options);
			const resolver = this.get(type, mergedOptions);
			childCache.set(options, resolver);
			return resolver;
		};
		this.hooks.resolver.for(type).call(resolver, resolveOptions);
		return resolver;
	}
};