webpack/lib/loaders/LoaderPlugin.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports 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 { markNotCacheable } = require("../loaders/LoaderRunner");
const NormalModule = require("../module/NormalModule");
const LazySet = require("../util/LazySet");
const LoaderDependency = require("./LoaderDependency");
const LoaderImportDependency = require("./LoaderImportDependency");

/** @import { RawSourceMap } from "webpack-sources" */
/**
 * @import {
 * 	DependencyConstructor,
 * 	ExecuteModuleExports,
 * 	ExecuteModuleResult,
 * 	FileSystemDependencies
 * } from "../Compilation"
 */
/** @import Compiler from "../Compiler" */
/** @import Module, { BuildInfo } from "../module/Module" */

/**
 * Defines the import module callback callback.
 * @callback ImportModuleCallback
 * @param {(Error | null)=} err error object
 * @param {ExecuteModuleExports=} exports exports of the evaluated module
 * @returns {void}
 */

/**
 * Defines the import module options type used by this module.
 * @typedef {object} ImportModuleOptions
 * @property {string=} layer the target layer
 * @property {string=} publicPath the target public path
 * @property {string=} baseUri target base uri
 */

/**
 * @callback LoadModuleCallback
 * @param {Error | null} err error object
 * @param {(string | Buffer)=} source source of the loaded module
 * @param {(object | null)=} sourceMap source map of the loaded module
 * @param {Module=} module the loaded module
 * @returns {void}
 */

/**
 * `importModule` takes a callback or, given none, answers with a promise, and
 * TypeScript reads an intersection of call signatures as an overload set
 * @typedef {{ (request: string, options: ImportModuleOptions | undefined, callback: ImportModuleCallback): void } & { (request: string, options?: ImportModuleOptions): Promise<ExecuteModuleExports> }} ImportModuleMethod
 */

/**
 * These properties are added by the LoaderPlugin
 * @typedef {object} LoaderPluginLoaderContext
 * @property {(request: string, callback: LoadModuleCallback) => void} loadModule Resolves the given request to a module, applies all configured loaders and calls
 * back with the generated source, the sourceMap and the module instance (usually an
 * instance of NormalModule). Use this function if you need to know the source code
 * of another module to generate the result.
 * @property {ImportModuleMethod} importModule
 */

const PLUGIN_NAME = "LoaderPlugin";

class LoaderPlugin {
	/**
	 * Applies the plugin by registering its hooks on the compiler.
	 * @param {Compiler} compiler the compiler instance
	 * @returns {void}
	 */
	apply(compiler) {
		compiler.hooks.compilation.tap(
			PLUGIN_NAME,
			(compilation, { normalModuleFactory }) => {
				compilation.dependencyFactories.set(
					LoaderDependency,
					normalModuleFactory
				);
				compilation.dependencyFactories.set(
					LoaderImportDependency,
					normalModuleFactory
				);
			}
		);

		compiler.hooks.compilation.tap(PLUGIN_NAME, (compilation) => {
			const moduleGraph = compilation.moduleGraph;
			NormalModule.getCompilationHooks(compilation).loader.tap(
				PLUGIN_NAME,
				(loaderContext) => {
					loaderContext.loadModule = (request, callback) => {
						const dep = new LoaderDependency(request);
						dep.loc = {
							name: request
						};
						const factory = compilation.dependencyFactories.get(
							/** @type {DependencyConstructor} */
							(dep.constructor)
						);
						if (factory === undefined) {
							return callback(
								new Error(
									`No module factory available for dependency type: ${dep.constructor.name}`
								)
							);
						}
						const oldFactorizeQueueContext =
							compilation.factorizeQueue.getContext();
						compilation.factorizeQueue.setContext("load-module");
						const oldAddModuleQueueContext =
							compilation.addModuleQueue.getContext();
						compilation.addModuleQueue.setContext("load-module");
						compilation.buildQueue.increaseParallelism();
						compilation.handleModuleCreation(
							{
								factory,
								dependencies: [dep],
								originModule:
									/** @type {NormalModule} */
									(loaderContext._module),
								context: loaderContext.context,
								recursive: false
							},
							(err) => {
								compilation.factorizeQueue.setContext(oldFactorizeQueueContext);
								compilation.addModuleQueue.setContext(oldAddModuleQueueContext);
								compilation.buildQueue.decreaseParallelism();
								if (err) {
									return callback(err);
								}
								const referencedModule = moduleGraph.getModule(dep);
								if (!referencedModule) {
									return callback(new Error("Cannot load the module"));
								}
								if (referencedModule.getNumberOfErrors() > 0) {
									return callback(
										new Error("The loaded module contains errors")
									);
								}
								const moduleSource = referencedModule.originalSource();
								if (!moduleSource) {
									return callback(
										new Error(
											"The module created for a LoaderDependency must have an original source"
										)
									);
								}
								/** @type {null | RawSourceMap} */
								let map;
								/** @type {string | Buffer | undefined} */
								let source;
								if (moduleSource.sourceAndMap) {
									const sourceAndMap = moduleSource.sourceAndMap();
									map = sourceAndMap.map;
									source = sourceAndMap.source;
								} else {
									map = moduleSource.map();
									source = moduleSource.source();
								}
								/** @type {FileSystemDependencies} */
								const fileDependencies = new LazySet();
								/** @type {FileSystemDependencies} */
								const contextDependencies = new LazySet();
								/** @type {FileSystemDependencies} */
								const missingDependencies = new LazySet();
								/** @type {FileSystemDependencies} */
								const buildDependencies = new LazySet();
								referencedModule.addCacheDependencies(
									fileDependencies,
									contextDependencies,
									missingDependencies,
									buildDependencies
								);

								for (const d of fileDependencies) {
									loaderContext.addDependency(d);
								}
								for (const d of contextDependencies) {
									loaderContext.addContextDependency(d);
								}
								for (const d of missingDependencies) {
									loaderContext.addMissingDependency(d);
								}
								for (const d of buildDependencies) {
									loaderContext.addBuildDependency(d);
								}
								return callback(null, source, map, referencedModule);
							}
						);
					};

					/**
					 * Processes the provided request.
					 * @param {string} request the request string to load the module from
					 * @param {ImportModuleOptions} options options
					 * @param {ImportModuleCallback} callback callback returning the exports
					 * @returns {void}
					 */
					const importModule = (request, options, callback) => {
						const dep = new LoaderImportDependency(request);
						dep.loc = {
							name: request
						};
						const factory = compilation.dependencyFactories.get(
							/** @type {DependencyConstructor} */
							(dep.constructor)
						);
						if (factory === undefined) {
							return callback(
								new Error(
									`No module factory available for dependency type: ${dep.constructor.name}`
								)
							);
						}

						const oldFactorizeQueueContext =
							compilation.factorizeQueue.getContext();
						compilation.factorizeQueue.setContext("import-module");
						const oldAddModuleQueueContext =
							compilation.addModuleQueue.getContext();
						compilation.addModuleQueue.setContext("import-module");
						compilation.buildQueue.increaseParallelism();
						compilation.handleModuleCreation(
							{
								factory,
								dependencies: [dep],
								originModule:
									/** @type {NormalModule} */
									(loaderContext._module),
								contextInfo: {
									issuerLayer: options.layer
								},
								context: loaderContext.context,
								connectOrigin: false,
								checkCycle: true
							},
							(err) => {
								compilation.factorizeQueue.setContext(oldFactorizeQueueContext);
								compilation.addModuleQueue.setContext(oldAddModuleQueueContext);
								compilation.buildQueue.decreaseParallelism();
								if (err) {
									return callback(err);
								}
								const referencedModule = moduleGraph.getModule(dep);
								if (!referencedModule) {
									return callback(new Error("Cannot load the module"));
								}
								compilation.buildQueue.increaseParallelism();
								compilation.executeModule(
									referencedModule,
									{
										entryOptions: {
											baseUri: options.baseUri,
											publicPath: options.publicPath
										}
									},
									(err, result) => {
										compilation.buildQueue.decreaseParallelism();
										if (err) return callback(err);
										const {
											fileDependencies,
											contextDependencies,
											missingDependencies,
											buildDependencies,
											cacheable,
											notCacheableReasons,
											assets,
											exports
										} = /** @type {ExecuteModuleResult} */ (result);
										for (const d of fileDependencies) {
											loaderContext.addDependency(d);
										}
										for (const d of contextDependencies) {
											loaderContext.addContextDependency(d);
										}
										for (const d of missingDependencies) {
											loaderContext.addMissingDependency(d);
										}
										for (const d of buildDependencies) {
											loaderContext.addBuildDependency(d);
										}
										if (cacheable === false) {
											markNotCacheable(loaderContext, notCacheableReasons);
										}
										for (const [name, { source, info }] of assets) {
											const buildInfo =
												/** @type {BuildInfo} */
												(
													/** @type {NormalModule} */ (loaderContext._module)
														.buildInfo
												);
											if (!buildInfo.assets) {
												buildInfo.assets = Object.create(null);
												buildInfo.assetsInfo = new Map();
											}
											/** @type {NonNullable<BuildInfo["assets"]>} */
											(buildInfo.assets)[name] = source;
											/** @type {NonNullable<BuildInfo["assetsInfo"]>} */
											(buildInfo.assetsInfo).set(name, info);
										}
										callback(null, exports);
									}
								);
							}
						);
					};

					// @ts-expect-error overloading doesn't work
					loaderContext.importModule = (request, options, callback) => {
						if (!callback) {
							return new Promise((resolve, reject) => {
								importModule(request, options || {}, (err, result) => {
									if (err) reject(err);
									else resolve(result);
								});
							});
						}
						return importModule(request, options || {}, callback);
					};
				}
			);
		});
	}
}

module.exports = LoaderPlugin;