webpack/lib/dependencies/RequireContextPlugin.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 RequireContextDependency = require("./RequireContextDependency");
const ContextElementDependency = require("./ContextElementDependency");

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

class RequireContextPlugin {
	constructor(modulesDirectories, extensions, mainFiles) {
		if (!Array.isArray(modulesDirectories)) {
			throw new Error("modulesDirectories must be an array");
		}
		if (!Array.isArray(extensions)) {
			throw new Error("extensions must be an array");
		}
		this.modulesDirectories = modulesDirectories;
		this.extensions = extensions;
		this.mainFiles = mainFiles;
	}

	apply(compiler) {
		compiler.hooks.compilation.tap(
			"RequireContextPlugin",
			(compilation, { contextModuleFactory, normalModuleFactory }) => {
				compilation.dependencyFactories.set(
					RequireContextDependency,
					contextModuleFactory
				);
				compilation.dependencyTemplates.set(
					RequireContextDependency,
					new RequireContextDependency.Template()
				);

				compilation.dependencyFactories.set(
					ContextElementDependency,
					normalModuleFactory
				);

				const handler = (parser, parserOptions) => {
					if (
						parserOptions.requireContext !== undefined &&
						!parserOptions.requireContext
					)
						return;

					new RequireContextDependencyParserPlugin().apply(parser);
				};

				normalModuleFactory.hooks.parser
					.for("javascript/auto")
					.tap("RequireContextPlugin", handler);
				normalModuleFactory.hooks.parser
					.for("javascript/dynamic")
					.tap("RequireContextPlugin", handler);

				contextModuleFactory.hooks.alternatives.tap(
					"RequireContextPlugin",
					items => {
						if (items.length === 0) return items;
						return items
							.map(obj => {
								return this.extensions
									.filter(ext => {
										const l = obj.request.length;
										return (
											l > ext.length &&
											obj.request.substr(l - ext.length, l) === ext
										);
									})
									.map(ext => {
										const l = obj.request.length;
										return {
											context: obj.context,
											request: obj.request.substr(0, l - ext.length)
										};
									})
									.concat(obj);
							})
							.reduce((a, b) => a.concat(b), []);
					}
				);

				contextModuleFactory.hooks.alternatives.tap(
					"RequireContextPlugin",
					items => {
						if (items.length === 0) return items;
						return items
							.map(obj => {
								return this.mainFiles
									.filter(mainFile => {
										const l = obj.request.length;
										return (
											l > mainFile.length + 1 &&
											obj.request.substr(l - mainFile.length - 1, l) ===
												"/" + mainFile
										);
									})
									.map(mainFile => {
										const l = obj.request.length;
										return [
											{
												context: obj.context,
												request: obj.request.substr(0, l - mainFile.length)
											},
											{
												context: obj.context,
												request: obj.request.substr(0, l - mainFile.length - 1)
											}
										];
									})
									.reduce((a, b) => a.concat(b), [])
									.concat(obj);
							})
							.reduce((a, b) => a.concat(b), []);
					}
				);

				contextModuleFactory.hooks.alternatives.tap(
					"RequireContextPlugin",
					items => {
						if (items.length === 0) return items;
						return items.map(obj => {
							for (let i = 0; i < this.modulesDirectories.length; i++) {
								const dir = this.modulesDirectories[i];
								const idx = obj.request.indexOf("./" + dir + "/");
								if (idx === 0) {
									obj.request = obj.request.slice(dir.length + 3);
									break;
								}
							}
							return obj;
						});
					}
				);
			}
		);
	}
}
module.exports = RequireContextPlugin;