webpack/lib/dependencies/CachedConstDependency.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 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("../Dependency")} Dependency */
/** @typedef {import("../Dependency").UpdateHashContext} UpdateHashContext */
/** @typedef {import("../DependencyTemplate").DependencyTemplateContext} DependencyTemplateContext */
/** @typedef {import("../javascript/JavascriptParser").Range} Range */
/** @typedef {import("../serialization/ObjectMiddleware").ObjectDeserializerContext} ObjectDeserializerContext */
/** @typedef {import("../serialization/ObjectMiddleware").ObjectSerializerContext} ObjectSerializerContext */
/** @typedef {import("../util/Hash")} Hash */

class CachedConstDependency extends NullDependency {
	/**
	 * Creates an instance of CachedConstDependency.
	 * @param {string} expression expression
	 * @param {Range | null} range range
	 * @param {string} identifier identifier
	 * @param {number=} place place where we inject the expression
	 */
	constructor(
		expression,
		range,
		identifier,
		place = CachedConstDependency.PLACE_MODULE
	) {
		super();

		this.expression = expression;
		this.range = range;
		this.identifier = identifier;
		this.place = place;
		/** @type {undefined | string} */
		this._hashUpdate = undefined;
	}

	/**
	 * Create hash update.
	 * @returns {string} hash update
	 */
	_createHashUpdate() {
		return `${this.place}${this.identifier}${this.range}${this.expression}`;
	}

	/**
	 * 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) {
		if (this._hashUpdate === undefined) {
			this._hashUpdate = this._createHashUpdate();
		}
		hash.update(this._hashUpdate);
	}

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

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

		super.serialize(context);
	}

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

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

		super.deserialize(context);
	}
}

CachedConstDependency.PLACE_MODULE = 10;
CachedConstDependency.PLACE_CHUNK = 20;

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

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

		(dep.place === CachedConstDependency.PLACE_MODULE
			? initFragments
			: chunkInitFragments
		).push(
			new InitFragment(
				`var ${dep.identifier} = ${dep.expression};\n`,
				InitFragment.STAGE_CONSTANTS,
				// For a chunk we inject expression after imports
				dep.place === CachedConstDependency.PLACE_MODULE ? 0 : 10,
				`const ${dep.identifier}`
			)
		);

		if (typeof dep.range === "number") {
			source.insert(dep.range, dep.identifier);
		} else if (dep.range !== null) {
			source.replace(dep.range[0], dep.range[1] - 1, dep.identifier);
		}
	}
};

module.exports = CachedConstDependency;