webpack/lib/library/AssignLibraryPlugin.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 { ConcatSource } = require("webpack-sources");
const propertyAccess = require("../util/propertyAccess");
const AbstractLibraryPlugin = require("./AbstractLibraryPlugin");

/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("../../declarations/WebpackOptions").LibraryOptions} LibraryOptions */
/** @typedef {import("../../declarations/WebpackOptions").LibraryType} LibraryType */
/** @typedef {import("../Chunk")} Chunk */
/** @typedef {import("../Compilation").ChunkHashContext} ChunkHashContext */
/** @typedef {import("../Compiler")} Compiler */
/** @typedef {import("../javascript/JavascriptModulesPlugin").RenderContext} RenderContext */
/** @typedef {import("../util/Hash")} Hash */
/** @template T @typedef {import("./AbstractLibraryPlugin").LibraryContext<T>} LibraryContext<T> */

/**
 * @param {string[]} accessor variable plus properties
 * @param {number} existingLength items of accessor that are existing already
 * @param {boolean=} initLast if the last property should also be initialized to an object
 * @returns {string} code to access the accessor while initializing
 */
const accessWithInit = (accessor, existingLength, initLast = false) => {
	// This generates for [a, b, c, d]:
	// (((a = typeof a === "undefined" ? {} : a).b = a.b || {}).c = a.b.c || {}).d
	const base = accessor[0];
	if (accessor.length === 1 && !initLast) return base;
	let current =
		existingLength > 0
			? base
			: `(${base} = typeof ${base} === "undefined" ? {} : ${base})`;

	// i is the current position in accessor that has been printed
	let i = 1;

	// all properties printed so far (excluding base)
	let propsSoFar;

	// if there is existingLength, print all properties until this position as property access
	if (existingLength > i) {
		propsSoFar = accessor.slice(1, existingLength);
		i = existingLength;
		current += propertyAccess(propsSoFar);
	} else {
		propsSoFar = [];
	}

	// all remaining properties (except the last one when initLast is not set)
	// should be printed as initializer
	const initUntil = initLast ? accessor.length : accessor.length - 1;
	for (; i < initUntil; i++) {
		const prop = accessor[i];
		propsSoFar.push(prop);
		current = `(${current}${propertyAccess([prop])} = ${base}${propertyAccess(
			propsSoFar
		)} || {})`;
	}

	// print the last property as property access if not yet printed
	if (i < accessor.length)
		current = `${current}${propertyAccess([accessor[accessor.length - 1]])}`;

	return current;
};

/**
 * @typedef {Object} AssignLibraryPluginOptions
 * @property {LibraryType} type
 * @property {string[] | "global"} prefix name prefix
 * @property {string | false} declare declare name as variable
 * @property {"error"|"copy"|"assign"} unnamed behavior for unnamed library name
 */

/**
 * @typedef {Object} AssignLibraryPluginParsed
 * @property {string | string[]} name
 */

/**
 * @typedef {AssignLibraryPluginParsed} T
 * @extends {AbstractLibraryPlugin<AssignLibraryPluginParsed>}
 */
class AssignLibraryPlugin extends AbstractLibraryPlugin {
	/**
	 * @param {AssignLibraryPluginOptions} options the plugin options
	 */
	constructor(options) {
		super({
			pluginName: "AssignLibraryPlugin",
			type: options.type
		});
		this.prefix = options.prefix;
		this.declare = options.declare;
		this.unnamed = options.unnamed;
	}

	/**
	 * @param {LibraryOptions} library normalized library option
	 * @returns {T | false} preprocess as needed by overriding
	 */
	parseOptions(library) {
		const { name } = library;
		if (this.unnamed === "error") {
			if (typeof name !== "string" && !Array.isArray(name)) {
				throw new Error("Library name must be a string or string array");
			}
		} else {
			if (name && typeof name !== "string" && !Array.isArray(name)) {
				throw new Error("Library name must be a string, string array or unset");
			}
		}
		return {
			name: /** @type {string|string[]=} */ (name)
		};
	}

	/**
	 * @param {Source} source source
	 * @param {RenderContext} renderContext render context
	 * @param {LibraryContext<T>} libraryContext context
	 * @returns {Source} source with library export
	 */
	render(source, { chunkGraph, moduleGraph, chunk }, { options, compilation }) {
		const prefix =
			this.prefix === "global"
				? [compilation.outputOptions.globalObject]
				: this.prefix;
		const fullName = options.name ? prefix.concat(options.name) : prefix;
		const fullNameResolved = fullName.map(n =>
			compilation.getPath(n, {
				chunk
			})
		);
		const result = new ConcatSource();
		if (this.declare) {
			const base = fullNameResolved[0];
			result.add(`${this.declare} ${base};`);
		}
		if (!options.name && this.unnamed === "copy") {
			result.add(
				`(function(e, a) { for(var i in a) e[i] = a[i]; if(a.__esModule) Object.defineProperty(e, "__esModule", { value: true }); }(${accessWithInit(
					fullNameResolved,
					prefix.length,
					true
				)},\n`
			);
			result.add(source);
			result.add("\n))");
		} else {
			result.add(
				`${accessWithInit(fullNameResolved, prefix.length, false)} =\n`
			);
			result.add(source);
		}
		return result;
	}

	/**
	 * @param {Chunk} chunk the chunk
	 * @param {Hash} hash hash
	 * @param {ChunkHashContext} chunkHashContext chunk hash context
	 * @param {LibraryContext<T>} libraryContext context
	 * @returns {void}
	 */
	chunkHash(chunk, hash, chunkHashContext, { options, compilation }) {
		hash.update("AssignLibraryPlugin");
		const prefix =
			this.prefix === "global"
				? [compilation.outputOptions.globalObject]
				: this.prefix;
		const fullName = options.name ? prefix.concat(options.name) : prefix;
		const fullNameResolved = fullName.map(n =>
			compilation.getPath(n, {
				chunk
			})
		);
		if (!options.name && this.unnamed === "copy") {
			hash.update("copy");
		}
		if (this.declare) {
			hash.update(this.declare);
		}
		hash.update(fullNameResolved.join("."));
	}
}

module.exports = AssignLibraryPlugin;