webpack/lib/dependencies/CachedConstDependency.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 Florent Cailhol @ooflorent
*/

"use strict";

const DependencyTemplate = require("../DependencyTemplate");
const InitFragment = require("../InitFragment");
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("../DependencyTemplates")} DependencyTemplates */
/** @typedef {import("../ModuleGraph")} ModuleGraph */
/** @typedef {import("../RuntimeTemplate")} RuntimeTemplate */
/** @typedef {import("../util/Hash")} Hash */

class CachedConstDependency extends NullDependency {
	constructor(expression, range, identifier) {
		super();

		this.expression = expression;
		this.range = range;
		this.identifier = identifier;
		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)
			this._hashUpdate = "" + this.identifier + this.range + this.expression;
		hash.update(this._hashUpdate);
	}

	serialize(context) {
		const { write } = context;

		write(this.expression);
		write(this.range);
		write(this.identifier);

		super.serialize(context);
	}

	deserialize(context) {
		const { read } = context;

		this.expression = read();
		this.range = read();
		this.identifier = read();

		super.deserialize(context);
	}
}

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

CachedConstDependency.Template = class CachedConstDependencyTemplate extends (
	DependencyTemplate
) {
	/**
	 * @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, dependencyTemplates, initFragments }
	) {
		const dep = /** @type {CachedConstDependency} */ (dependency);

		initFragments.push(
			new InitFragment(
				`var ${dep.identifier} = ${dep.expression};\n`,
				InitFragment.STAGE_CONSTANTS,
				0,
				`const ${dep.identifier}`
			)
		);

		if (typeof dep.range === "number") {
			source.insert(dep.range, dep.identifier);

			return;
		}

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

module.exports = CachedConstDependency;