webpack/lib/ExternalModuleFactoryPlugin.js

/*
	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];

				/**
				 * @param {string|boolean} value the external config
				 * @param {string|undefined} type type of external
				 * @param {function(Error=, ExternalModule=): void} callback callback
				 * @returns {void}
				 */
				const handleExternal = (value, type, callback) => {
					if (value === false) {
						// Not externals, fallback to original factory
						return factory(data, callback);
					}
					/** @type {string} */
					let externalConfig;
					if (value === true) {
						externalConfig = dependency.request;
					} else {
						externalConfig = value;
					}
					// When no explicit type is specified, extract it from the externalConfig
					if (type === undefined && /^[a-z0-9]+ /.test(externalConfig)) {
						const idx = externalConfig.indexOf(" ");
						type = externalConfig.substr(0, idx);
						externalConfig = externalConfig.substr(idx + 1);
					}
					callback(
						null,
						new ExternalModule(
							externalConfig,
							type || globalType,
							dependency.request
						)
					);
				};

				const handleExternals = (externals, callback) => {
					if (typeof externals === "string") {
						if (externals === dependency.request) {
							return handleExternal(dependency.request, undefined, 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, undefined, callback);
						}
					} else if (typeof externals === "function") {
						const cb = (err, value, type) => {
							if (err) return callback(err);
							if (value !== undefined) {
								handleExternal(value, type, callback);
							} else {
								callback();
							}
						};
						if (externals.length === 3) {
							// TODO webpack 5 insert deprecation message here
							// TODO webpack 6 remove this
							externals.call(null, context, dependency.request, cb);
						} else {
							externals(
								{
									context,
									request: dependency.request
								},
								cb
							);
						}
						return;
					} else if (
						typeof externals === "object" &&
						Object.prototype.hasOwnProperty.call(externals, dependency.request)
					) {
						return handleExternal(
							externals[dependency.request],
							undefined,
							callback
						);
					}
					callback();
				};

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