webpack/lib/dependencies/ConstDependency.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support 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 makeSerializable = require("../util/makeSerializable");
const NullDependency = require("./NullDependency");

/** @typedef {import("webpack-sources").ReplaceSource} ReplaceSource */
/** @typedef {import("../ChunkGraph")} ChunkGraph */
/** @typedef {import("../Dependency")} Dependency */
/** @typedef {import("../Dependency").UpdateHashContext} UpdateHashContext */
/** @typedef {import("../DependencyTemplate").DependencyTemplateContext} DependencyTemplateContext */
/** @typedef {import("../ModuleGraph")} ModuleGraph */
/** @typedef {import("../ModuleGraphConnection").ConnectionState} ConnectionState */
/** @typedef {import("../util/Hash")} Hash */

class ConstDependency extends NullDependency {
	/**
	 * @param {string} expression the expression
	 * @param {number|[number, number]} range the source range
	 * @param {string[]=} runtimeRequirements runtime requirements
	 */
	constructor(expression, range, runtimeRequirements) {
		super();
		this.expression = expression;
		this.range = range;
		this.runtimeRequirements = runtimeRequirements
			? new Set(runtimeRequirements)
			: null;
		this._hashUpdate = undefined;
	}

	/**
	 * Update the hash
	 * @param {Hash} hash hash to be updated
	 * @param {UpdateHashContext} context context
	 * @returns {void}
	 */
	updateHash(hash, context) {
		if (this._hashUpdate === undefined) {
			let hashUpdate = "" + this.range + "|" + this.expression;
			if (this.runtimeRequirements) {
				for (const item of this.runtimeRequirements) {
					hashUpdate += "|";
					hashUpdate += item;
				}
			}
			this._hashUpdate = hashUpdate;
		}
		hash.update(this._hashUpdate);
	}

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

	serialize(context) {
		const { write } = context;
		write(this.expression);
		write(this.range);
		write(this.runtimeRequirements);
		super.serialize(context);
	}

	deserialize(context) {
		const { read } = context;
		this.expression = read();
		this.range = read();
		this.runtimeRequirements = read();
		super.deserialize(context);
	}
}

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

ConstDependency.Template = class ConstDependencyTemplate extends (
	NullDependency.Template
) {
	/**
	 * @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 dep = /** @type {ConstDependency} */ (dependency);
		if (dep.runtimeRequirements) {
			for (const req of dep.runtimeRequirements) {
				templateContext.runtimeRequirements.add(req);
			}
		}
		if (typeof dep.range === "number") {
			source.insert(dep.range, dep.expression);
			return;
		}

		source.replace(dep.range[0], dep.range[1] - 1, dep.expression);
	}
};

module.exports = ConstDependency;