webpack/lib/css/CssExportsGenerator.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 Sergey Melyukov @smelukov
*/

"use strict";

const { ReplaceSource, RawSource, ConcatSource } = require("webpack-sources");
const { UsageState } = require("../ExportsInfo");
const Generator = require("../Generator");
const RuntimeGlobals = require("../RuntimeGlobals");
const Template = require("../Template");

/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("../Dependency")} Dependency */
/** @typedef {import("../Generator").GenerateContext} GenerateContext */
/** @typedef {import("../Generator").UpdateHashContext} UpdateHashContext */
/** @typedef {import("../Module").ConcatenationBailoutReasonContext} ConcatenationBailoutReasonContext */
/** @typedef {import("../NormalModule")} NormalModule */
/** @typedef {import("../util/Hash")} Hash */

const TYPES = new Set(["javascript"]);

class CssExportsGenerator extends Generator {
	constructor() {
		super();
	}

	// TODO add getConcatenationBailoutReason to allow concatenation
	// but how to make it have a module id

	/**
	 * @param {NormalModule} module module for which the code should be generated
	 * @param {GenerateContext} generateContext context for generate
	 * @returns {Source} generated code
	 */
	generate(module, generateContext) {
		const source = new ReplaceSource(new RawSource(""));
		const initFragments = [];
		const cssExports = new Map();

		generateContext.runtimeRequirements.add(RuntimeGlobals.module);

		const runtimeRequirements = new Set();

		const templateContext = {
			runtimeTemplate: generateContext.runtimeTemplate,
			dependencyTemplates: generateContext.dependencyTemplates,
			moduleGraph: generateContext.moduleGraph,
			chunkGraph: generateContext.chunkGraph,
			module,
			runtime: generateContext.runtime,
			runtimeRequirements: runtimeRequirements,
			concatenationScope: generateContext.concatenationScope,
			codeGenerationResults: generateContext.codeGenerationResults,
			initFragments,
			cssExports
		};

		const handleDependency = dependency => {
			const constructor = /** @type {new (...args: any[]) => Dependency} */ (
				dependency.constructor
			);
			const template = generateContext.dependencyTemplates.get(constructor);
			if (!template) {
				throw new Error(
					"No template for dependency: " + dependency.constructor.name
				);
			}

			template.apply(dependency, source, templateContext);
		};
		module.dependencies.forEach(handleDependency);

		if (generateContext.concatenationScope) {
			const source = new ConcatSource();
			const usedIdentifiers = new Set();
			for (const [k, v] of cssExports) {
				let identifier = Template.toIdentifier(k);
				let i = 0;
				while (usedIdentifiers.has(identifier)) {
					identifier = Template.toIdentifier(k + i);
				}
				usedIdentifiers.add(identifier);
				generateContext.concatenationScope.registerExport(k, identifier);
				source.add(
					`${
						generateContext.runtimeTemplate.supportsConst ? "const" : "var"
					} ${identifier} = ${JSON.stringify(v)};\n`
				);
			}
			return source;
		} else {
			const otherUsed =
				generateContext.moduleGraph
					.getExportsInfo(module)
					.otherExportsInfo.getUsed(generateContext.runtime) !==
				UsageState.Unused;
			if (otherUsed) {
				generateContext.runtimeRequirements.add(
					RuntimeGlobals.makeNamespaceObject
				);
			}
			return new RawSource(
				`${otherUsed ? `${RuntimeGlobals.makeNamespaceObject}(` : ""}${
					module.moduleArgument
				}.exports = {\n${Array.from(
					cssExports,
					([k, v]) => `\t${JSON.stringify(k)}: ${JSON.stringify(v)}`
				).join(",\n")}\n}${otherUsed ? ")" : ""};`
			);
		}
	}

	/**
	 * @param {NormalModule} module fresh module
	 * @returns {Set<string>} available types (do not mutate)
	 */
	getTypes(module) {
		return TYPES;
	}

	/**
	 * @param {NormalModule} module the module
	 * @param {string=} type source type
	 * @returns {number} estimate size of the module
	 */
	getSize(module, type) {
		return 42;
	}

	/**
	 * @param {Hash} hash hash that will be modified
	 * @param {UpdateHashContext} updateHashContext context for updating hash
	 */
	updateHash(hash, { module }) {}
}

module.exports = CssExportsGenerator;