webpack/lib/dependencies/CommonJsRequireDependency.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 Dependency = require("../Dependency");
const makeSerializable = require("../util/makeSerializable");
const memoize = require("../util/memoize");
const {
	ESM_MODULE_EXPORTS_NAME,
	getRequireEsmModuleExportsAccess,
	isRequireEsmModuleExportsModule
} = require("./CommonJsDependencyHelpers");
const ModuleDependency = require("./ModuleDependency");

/** @typedef {import("webpack-sources").ReplaceSource} ReplaceSource */
/** @typedef {import("../Dependency").GetConditionFn} GetConditionFn */
/** @typedef {import("../Dependency").RawReferencedExports} RawReferencedExports */
/** @typedef {import("../Dependency").ReferencedExports} ReferencedExports */
/** @typedef {import("../DependencyTemplate").DependencyTemplateContext} DependencyTemplateContext */
/** @typedef {import("../Module")} Module */
/** @typedef {import("../ModuleGraph")} ModuleGraph */
/** @typedef {import("../javascript/JavascriptParser").Range} Range */
/** @typedef {import("../util/runtime").RuntimeSpec} RuntimeSpec */
/** @typedef {import("./HarmonyImportGuard").DependencyGuard} DependencyGuard */
/** @typedef {import("../serialization/ObjectMiddleware").ObjectDeserializerContext<[RawReferencedExports | null, Range | undefined, DependencyGuard[] | undefined]>} ObjectDeserializerContext */
/** @typedef {import("../serialization/ObjectMiddleware").ObjectSerializerContext<[RawReferencedExports | null, Range | undefined, DependencyGuard[] | undefined]>} ObjectSerializerContext */

const getHarmonyImportGuard = memoize(() => require("./HarmonyImportGuard"));

/**
 * Trims a member-access path at the first segment that is definitively not a
 * provided export of the module. Such a segment is a runtime property (e.g. an
 * array/object prototype method like `arr.includes`), so only the value up to
 * that point is observed; referencing the whole value keeps its data intact
 * instead of tree-shaking it away. Real named exports (`utils.foo`) are kept.
 * @param {import("../ExportsInfo")} exportsInfo module exports info
 * @param {string[]} name member-access path
 * @returns {string[]} the provided prefix of the path
 */
const trimToProvidedPrefix = (exportsInfo, name) => {
	let current = exportsInfo;
	for (let i = 0; i < name.length; i++) {
		const exportInfo = current.getReadOnlyExportInfo(name[i]);
		if (exportInfo.provided === false) return name.slice(0, i);
		const nested = exportInfo.exportsInfo;
		if (!nested) return name;
		current = nested;
	}
	return name;
};

class CommonJsRequireDependency extends ModuleDependency {
	/**
	 * Creates an instance of CommonJsRequireDependency.
	 * @param {string} request request
	 * @param {Range=} range location in source code of the string-literal argument (gets replaced by the module id)
	 * @param {string=} context request context
	 * @param {RawReferencedExports | null=} referencedExports list of referenced exports
	 * @param {Range=} valueRange location in source code of the whole `require(...)` call (for `require(esm)` interop)
	 */
	constructor(
		request,
		range,
		context,
		referencedExports = null,
		valueRange = undefined
	) {
		super(request);
		this.range = range;
		/** @type {string | undefined} */
		this._context = context;
		/** @type {RawReferencedExports | null} */
		this.referencedExports = referencedExports;
		this.valueRange = valueRange;
		/** @type {DependencyGuard[] | undefined} */
		this.branchGuards = undefined;
	}

	get type() {
		return "cjs require";
	}

	get category() {
		return "commonjs";
	}

	/**
	 * Returns function to determine if the connection is active.
	 * @param {ModuleGraph} moduleGraph module graph
	 * @returns {null | false | GetConditionFn} function to determine if the connection is active
	 */
	getCondition(moduleGraph) {
		const guards = this.branchGuards;
		if (guards === undefined) return null;
		return (connection, runtime) =>
			!getHarmonyImportGuard().isDeadByGuards(guards, moduleGraph, runtime);
	}

	/**
	 * Returns list of exports referenced by this dependency
	 * @param {ModuleGraph} moduleGraph module graph
	 * @param {RuntimeSpec} runtime the runtime for which the module is analysed
	 * @returns {ReferencedExports} referenced exports
	 */
	getReferencedExports(moduleGraph, runtime) {
		const importedModule = moduleGraph.getModule(this);
		if (
			importedModule &&
			isRequireEsmModuleExportsModule(importedModule, moduleGraph)
		) {
			// `require(esm)` will unwrap the "module.exports" named export; only
			// that export is observable through this `require()` call.
			return [{ name: [ESM_MODULE_EXPORTS_NAME], canInline: false }];
		}
		if (!this.referencedExports) return Dependency.EXPORTS_OBJECT_REFERENCED;
		const exportsInfo = importedModule
			? moduleGraph.getExportsInfo(importedModule)
			: undefined;
		return this.referencedExports.map((name) => ({
			name: exportsInfo ? trimToProvidedPrefix(exportsInfo, name) : name,
			canMangle: false,
			canInline: false
		}));
	}

	/**
	 * Serializes this instance into the provided serializer context.
	 * @param {ObjectSerializerContext} context context
	 */
	serialize(context) {
		context
			.write(this.referencedExports)
			.write(this.valueRange)
			.write(this.branchGuards);
		super.serialize(context);
	}

	/**
	 * Restores this instance from the provided deserializer context.
	 * @param {ObjectDeserializerContext} context context
	 */
	deserialize(context) {
		this.referencedExports = context.read();
		const c1 = context.rest;
		this.valueRange = c1.read();
		const c2 = c1.rest;
		this.branchGuards = c2.read();
		super.deserialize(c2.rest);
	}
}

CommonJsRequireDependency.Template = class CommonJsRequireDependencyTemplate extends (
	ModuleDependency.Template
) {
	/**
	 * Applies the plugin by registering its hooks on the compiler.
	 * @param {Dependency} dependency the dependency for which the template should be applied
	 * @param {ReplaceSource} source the current replace source which can be modified
	 * @param {DependencyTemplateContext} templateContext the context object
	 * @returns {void}
	 */
	apply(
		dependency,
		source,
		{ runtimeTemplate, moduleGraph, chunkGraph, runtime }
	) {
		const dep = /** @type {CommonJsRequireDependency} */ (dependency);
		if (!dep.range) return;
		const connection = moduleGraph.getConnection(dep);
		// Dead branch: module is excluded and has no id; code is never executed.
		if (connection && !connection.isTargetActive(runtime)) {
			source.replace(dep.range[0], dep.range[1] - 1, "null /* dead branch */");
			return;
		}
		const importedModule = /** @type {Module} */ (moduleGraph.getModule(dep));
		const content = runtimeTemplate.moduleId({
			module: importedModule,
			chunkGraph,
			request: dep.request,
			weak: dep.weak
		});
		source.replace(dep.range[0], dep.range[1] - 1, content);

		if (dep.valueRange && importedModule) {
			const access = getRequireEsmModuleExportsAccess(
				importedModule,
				moduleGraph,
				runtime
			);
			if (access !== null) {
				source.insert(dep.valueRange[1], access);
			}
		}
	}
};

makeSerializable(
	CommonJsRequireDependency,
	"webpack/lib/dependencies/CommonJsRequireDependency"
);

module.exports = CommonJsRequireDependency;