webpack/lib/ExternalModuleFactoryPlugin.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 ExternalModule = require("./ExternalModule");

class ExternalModuleFactoryPlugin {
	constructor(type, externals) {
		this.type = type;
		this.externals = externals;
	}

	apply(normalModuleFactory) {
		const globalType = this.type;
		normalModuleFactory.hooks.factory.tap(
			"ExternalModuleFactoryPlugin",
			factory => (data, callback) => {
				const context = data.context;
				const dependency = data.dependencies[0];

				const handleExternal = (value, type, callback) => {
					if (typeof type === "function") {
						callback = type;
						type = undefined;
					}
					if (value === false) return factory(data, callback);
					if (value === true) value = dependency.request;
					if (type === undefined && /^[a-z0-9]+ /.test(value)) {
						const idx = value.indexOf(" ");
						type = value.substr(0, idx);
						value = value.substr(idx + 1);
					}
					callback(
						null,
						new ExternalModule(value, type || globalType, dependency.request)
					);
					return true;
				};

				const handleExternals = (externals, callback) => {
					if (typeof externals === "string") {
						if (externals === dependency.request) {
							return handleExternal(dependency.request, callback);
						}
					} else if (Array.isArray(externals)) {
						let i = 0;
						const next = () => {
							let asyncFlag;
							const handleExternalsAndCallback = (err, module) => {
								if (err) return callback(err);
								if (!module) {
									if (asyncFlag) {
										asyncFlag = false;
										return;
									}
									return next();
								}
								callback(null, module);
							};

							do {
								asyncFlag = true;
								if (i >= externals.length) return callback();
								handleExternals(externals[i++], handleExternalsAndCallback);
							} while (!asyncFlag);
							asyncFlag = false;
						};

						next();
						return;
					} else if (externals instanceof RegExp) {
						if (externals.test(dependency.request)) {
							return handleExternal(dependency.request, callback);
						}
					} else if (typeof externals === "function") {
						externals.call(
							null,
							context,
							dependency.request,
							(err, value, type) => {
								if (err) return callback(err);
								if (value !== undefined) {
									handleExternal(value, type, callback);
								} else {
									callback();
								}
							}
						);
						return;
					} else if (
						typeof externals === "object" &&
						Object.prototype.hasOwnProperty.call(externals, dependency.request)
					) {
						return handleExternal(externals[dependency.request], callback);
					}
					callback();
				};

				handleExternals(this.externals, (err, module) => {
					if (err) return callback(err);
					if (!module) return handleExternal(false, callback);
					return callback(null, module);
				});
			}
		);
	}
}
module.exports = ExternalModuleFactoryPlugin;