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 RuntimeGlobals = require("../RuntimeGlobals");
const {
	getDependencyUsedByExportsCondition
} = require("../optimize/InnerGraph");
const makeSerializable = require("../util/makeSerializable");
const {
	ESM_MODULE_EXPORTS_NAME,
	getRequireEsmModuleExportsAccess,
	isRequireEsmModuleExportsModule
} = require("./CommonJsDependencyHelpers");
const HarmonyImportGuard = require("./HarmonyImportGuard");
const ModuleDependency = require("./ModuleDependency");

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

/**
 * 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;
		/** @type {UsedByExports | undefined} */
		this.usedByExports = undefined;
		/** @type {boolean} */
		this._canConcatenate = false;
		// `new require(...)`; see the template for the return-value rule
		/** @type {boolean} */
		this.callNew = false;
	}

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

	get category() {
		return "commonjs";
	}

	/**
	 * Whether this require only evaluates the module (no exports read).
	 * @returns {boolean} true when referencedExports is an empty list
	 */
	isEvaluationOnly() {
		return (
			Array.isArray(this.referencedExports) &&
			this.referencedExports.length === 0
		);
	}

	/**
	 * 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 usedByExportsCondition =
			this.usedByExports !== undefined
				? getDependencyUsedByExportsCondition(this, moduleGraph)
				: null;
		if (usedByExportsCondition === false) return false;
		const guards = this.branchGuards;
		const evaluationOnly = this.isEvaluationOnly();
		if (
			usedByExportsCondition === null &&
			guards === undefined &&
			!evaluationOnly
		) {
			return null;
		}
		return (connection, runtime) => {
			if (
				usedByExportsCondition !== null &&
				usedByExportsCondition(connection, runtime) === false
			) {
				return false;
			}
			if (
				guards !== undefined &&
				HarmonyImportGuard.isDeadByGuards(guards, moduleGraph, runtime)
			) {
				return false;
			}
			if (evaluationOnly) {
				const refModule = connection.resolvedModule;
				if (!refModule) return true;
				return refModule.getSideEffectsConnectionState(moduleGraph);
			}
			return true;
		};
	}

	/**
	 * 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 (this.isEvaluationOnly()) {
			// Active `require(esm)` with side effects still unwraps `module.exports`.
			if (
				importedModule &&
				isRequireEsmModuleExportsModule(importedModule, moduleGraph)
			) {
				return [{ name: [ESM_MODULE_EXPORTS_NAME], canInline: false }];
			}
			return Dependency.NO_EXPORTS_REFERENCED;
		}
		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
		}));
	}

	/**
	 * Returns true if this dependency can be concatenated
	 * @param {boolean} concatenateCommonJsModules whether optimization.concatenateModules.commonjs is enabled
	 * @returns {boolean} true if this dependency can be concatenated
	 */
	canConcatenate(concatenateCommonJsModules) {
		return concatenateCommonJsModules && this._canConcatenate;
	}

	/**
	 * @param {ModuleGraphConnection} connection the active connection of this dependency
	 * @param {ConcatenationScope} concatenationScope the concatenation scope
	 * @returns {boolean} true when the call becomes a module reference
	 */
	rendersAsConcatenatedReference(connection, concatenationScope) {
		return (
			this._canConcatenate &&
			this.valueRange !== undefined &&
			concatenationScope.isModuleInScope(connection.module)
		);
	}

	/**
	 * Serializes this instance into the provided serializer context.
	 * @param {ObjectSerializerContext} context context
	 */
	serialize(context) {
		context
			.write(this.referencedExports)
			.write(this.valueRange)
			.write(this.branchGuards)
			.write(this._canConcatenate)
			.write(this.callNew)
			.write(this.usedByExports);
		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();
		const c3 = c2.rest;
		this._canConcatenate = c3.read();
		const c4 = c3.rest;
		this.callNew = c4.read();
		const c5 = c4.rest;
		this.usedByExports = c5.read();
		super.deserialize(c5.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, templateContext) {
		const {
			runtimeTemplate,
			moduleGraph,
			chunkGraph,
			runtime,
			concatenationScope
		} = templateContext;
		const dep = /** @type {CommonJsRequireDependency} */ (dependency);
		if (!dep.range) return;
		const connection = moduleGraph.getConnection(dep);
		if (connection && !connection.isTargetActive(runtime)) {
			const guards = dep.branchGuards;
			if (
				guards !== undefined &&
				HarmonyImportGuard.isDeadByGuards(guards, moduleGraph, runtime)
			) {
				// Dead branch: module is excluded and has no id; code is never executed.
				source.replace(
					dep.range[0],
					dep.range[1] - 1,
					"null /* dead branch */"
				);
				return;
			}
			// Unused side-effect-free require: drop the whole call expression.
			if (!dep.valueRange) return;
			source.replace(dep.valueRange[0], dep.valueRange[1] - 1, "0");
			return;
		}
		if (
			connection &&
			concatenationScope !== undefined &&
			dep.rendersAsConcatenatedReference(connection, concatenationScope)
		) {
			const valueRange = /** @type {Range} */ (dep.valueRange);
			let content = concatenationScope.createModuleReference(
				connection.module,
				{
					// `require(esm)` unwraps the "module.exports" export
					ids: isRequireEsmModuleExportsModule(connection.module, moduleGraph)
						? [ESM_MODULE_EXPORTS_NAME]
						: undefined,
					asiSafe: true,
					moduleExportsAccess: true
				}
			);
			// replacing the call drops the `new`, so apply the `new` return-value rule
			// here: object or function passes through, anything else gets a fresh instance
			if (dep.callNew) {
				templateContext.runtimeRequirements.add(
					RuntimeGlobals.constructRequire
				);
				content = `${RuntimeGlobals.constructRequire}(${content})`;
			}
			source.replace(valueRange[0], valueRange[1] - 1, content);
			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;