webpack/lib/dependencies/PureExpressionDependency.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 { UsageState } = require("../ExportsInfo");
const makeSerializable = require("../util/makeSerializable");
const { filterRuntime, runtimeToString } = require("../util/runtime");
const NullDependency = require("./NullDependency");

/** @typedef {import("webpack-sources").ReplaceSource} ReplaceSource */
/** @typedef {import("../Dependency")} Dependency */
/** @typedef {import("../Dependency").RuntimeSpec} RuntimeSpec */
/** @typedef {import("../Dependency").UpdateHashContext} UpdateHashContext */
/** @typedef {import("../DependencyTemplate").DependencyTemplateContext} DependencyTemplateContext */
/** @typedef {import("../Module")} Module */
/** @typedef {import("../ModuleGraph")} ModuleGraph */
/** @typedef {import("../ModuleGraphConnection").ConnectionState} ConnectionState */
/** @typedef {import("../javascript/JavascriptParser").Range} Range */
/** @typedef {import("../serialization/ObjectMiddleware").ObjectDeserializerContext} ObjectDeserializerContext */
/** @typedef {import("../serialization/ObjectMiddleware").ObjectSerializerContext} ObjectSerializerContext */
/** @typedef {import("../util/Hash")} Hash */

class PureExpressionDependency extends NullDependency {
	/**
	 * Creates an instance of PureExpressionDependency.
	 * @param {Range} range the source range
	 */
	constructor(range) {
		super();
		this.range = range;
		/** @type {Set<string> | false} */
		this.usedByExports = false;
	}

	/**
	 * Get runtime condition.
	 * @param {ModuleGraph} moduleGraph module graph
	 * @param {RuntimeSpec} runtime current runtimes
	 * @returns {boolean | RuntimeSpec} runtime condition
	 */
	_getRuntimeCondition(moduleGraph, runtime) {
		const usedByExports = this.usedByExports;
		if (usedByExports !== false) {
			const selfModule =
				/** @type {Module} */
				(moduleGraph.getParentModule(this));
			const exportsInfo = moduleGraph.getExportsInfo(selfModule);
			const runtimeCondition = filterRuntime(runtime, (runtime) => {
				for (const exportName of usedByExports) {
					if (exportsInfo.getUsed(exportName, runtime) !== UsageState.Unused) {
						return true;
					}
				}
				return false;
			});
			return runtimeCondition;
		}
		return false;
	}

	/**
	 * Updates the hash with the data contributed by this instance.
	 * @param {Hash} hash hash to be updated
	 * @param {UpdateHashContext} context context
	 * @returns {void}
	 */
	updateHash(hash, context) {
		const runtimeCondition = this._getRuntimeCondition(
			context.chunkGraph.moduleGraph,
			context.runtime
		);
		if (runtimeCondition === true) {
			return;
		} else if (runtimeCondition === false) {
			hash.update("null");
		} else {
			hash.update(
				`${runtimeToString(runtimeCondition)}|${runtimeToString(
					context.runtime
				)}`
			);
		}
		hash.update(String(this.range));
	}

	/**
	 * Gets module evaluation side effects state.
	 * @param {ModuleGraph} moduleGraph the module graph
	 * @returns {ConnectionState} how this dependency connects the module to referencing modules
	 */
	getModuleEvaluationSideEffectsState(moduleGraph) {
		return false;
	}

	/**
	 * Serializes this instance into the provided serializer context.
	 * @param {ObjectSerializerContext} context context
	 */
	serialize(context) {
		const { write } = context;
		write(this.range);
		write(this.usedByExports);
		super.serialize(context);
	}

	/**
	 * Restores this instance from the provided deserializer context.
	 * @param {ObjectDeserializerContext} context context
	 */
	deserialize(context) {
		const { read } = context;
		this.range = read();
		this.usedByExports = read();
		super.deserialize(context);
	}
}

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

PureExpressionDependency.Template = class PureExpressionDependencyTemplate extends (
	NullDependency.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,
		{ chunkGraph, moduleGraph, runtime, runtimeTemplate, runtimeRequirements }
	) {
		const dep = /** @type {PureExpressionDependency} */ (dependency);
		const runtimeCondition = dep._getRuntimeCondition(moduleGraph, runtime);
		if (runtimeCondition === true) {
			// Do nothing
		} else if (runtimeCondition === false) {
			source.insert(
				dep.range[0],
				"(/* unused pure expression or super */ null && ("
			);
			source.insert(dep.range[1], "))");
		} else {
			const condition = runtimeTemplate.runtimeConditionExpression({
				chunkGraph,
				runtime,
				runtimeCondition,
				runtimeRequirements
			});
			source.insert(
				dep.range[0],
				`(/* runtime-dependent pure expression or super */ ${condition} ? (`
			);
			source.insert(dep.range[1], ") : null)");
		}
	}
};

module.exports = PureExpressionDependency;