webpack/lib/dependencies/ExternalModuleInitFragment.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 Ivan Kopeykin @vankop
*/

"use strict";

const InitFragment = require("../InitFragment");
const makeSerializable = require("../util/makeSerializable");

/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("../Generator").GenerateContext} GenerateContext */
/** @typedef {import("../serialization/ObjectMiddleware").ObjectDeserializerContext} ObjectDeserializerContext */
/** @typedef {import("../serialization/ObjectMiddleware").ObjectSerializerContext} ObjectSerializerContext */
/** @typedef {Map<string, Set<string>>} ImportSpecifiers */

/**
 * @extends {InitFragment<GenerateContext>}
 */
class ExternalModuleInitFragment extends InitFragment {
	/**
	 * @param {string} importedModule imported module
	 * @param {Array<{ name: string, value?: string }> | ImportSpecifiers} specifiers import specifiers
	 * @param {string=} defaultImport default import
	 */
	constructor(importedModule, specifiers, defaultImport) {
		super(
			undefined,
			InitFragment.STAGE_CONSTANTS,
			0,
			`external module imports|${importedModule}|${defaultImport || "null"}`
		);
		this.importedModule = importedModule;
		if (Array.isArray(specifiers)) {
			/** @type {ImportSpecifiers} */
			this.specifiers = new Map();
			for (const { name, value } of specifiers) {
				let specifiers = this.specifiers.get(name);
				if (!specifiers) {
					specifiers = new Set();
					this.specifiers.set(name, specifiers);
				}
				specifiers.add(value || name);
			}
		} else {
			this.specifiers = specifiers;
		}
		this.defaultImport = defaultImport;
	}

	/**
	 * @param {ExternalModuleInitFragment} other other
	 * @returns {ExternalModuleInitFragment} ExternalModuleInitFragment
	 */
	merge(other) {
		const newSpecifiersMap = new Map(this.specifiers);
		for (const [name, specifiers] of other.specifiers) {
			if (newSpecifiersMap.has(name)) {
				const currentSpecifiers =
					/** @type {Set<string>} */
					(newSpecifiersMap.get(name));
				for (const spec of specifiers) currentSpecifiers.add(spec);
			} else {
				newSpecifiersMap.set(name, specifiers);
			}
		}
		return new ExternalModuleInitFragment(
			this.importedModule,
			newSpecifiersMap,
			this.defaultImport
		);
	}

	/**
	 * @param {GenerateContext} context context
	 * @returns {string | Source | undefined} the source code that will be included as initialization code
	 */
	getContent({ runtimeRequirements }) {
		const namedImports = [];

		for (const [name, specifiers] of this.specifiers) {
			for (const spec of specifiers) {
				if (spec === name) {
					namedImports.push(name);
				} else {
					namedImports.push(`${name} as ${spec}`);
				}
			}
		}

		let importsString =
			namedImports.length > 0 ? `{${namedImports.join(",")}}` : "";

		if (this.defaultImport) {
			importsString = `${this.defaultImport}${
				importsString ? `, ${importsString}` : ""
			}`;
		}

		return `import ${importsString} from ${JSON.stringify(
			this.importedModule
		)};`;
	}

	/**
	 * @param {ObjectSerializerContext} context context
	 */
	serialize(context) {
		super.serialize(context);
		const { write } = context;
		write(this.importedModule);
		write(this.specifiers);
		write(this.defaultImport);
	}

	/**
	 * @param {ObjectDeserializerContext} context context
	 */
	deserialize(context) {
		super.deserialize(context);
		const { read } = context;
		this.importedModule = read();
		this.specifiers = read();
		this.defaultImport = read();
	}
}

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

module.exports = ExternalModuleInitFragment;