webpack/lib/sharing/ShareRuntimeModule.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 Tobias Koppers @sokra
*/

"use strict";

const RuntimeGlobals = require("../RuntimeGlobals");
const RuntimeModule = require("../RuntimeModule");
const Template = require("../Template");
const {
	compareModulesByIdentifier,
	compareStrings
} = require("../util/comparators");

/** @typedef {import("../Chunk")} Chunk */
/** @typedef {import("../ChunkGraph")} ChunkGraph */
/** @typedef {import("../Compilation")} Compilation */
/** @typedef {import("../CodeGenerationResults")} CodeGenerationResults */

class ShareRuntimeModule extends RuntimeModule {
	constructor() {
		super("sharing");
	}

	/**
	 * Generates runtime code for this runtime module.
	 * @returns {string | null} runtime code
	 */
	generate() {
		const compilation = /** @type {Compilation} */ (this.compilation);
		const {
			runtimeTemplate,
			outputOptions: { uniqueName, ignoreBrowserWarnings }
		} = compilation;
		const codeGenerationResults =
			/** @type {CodeGenerationResults} */
			(compilation.codeGenerationResults);
		const chunkGraph = /** @type {ChunkGraph} */ (this.chunkGraph);
		/** @type {Map<string, Map<number, Set<string>>>} */
		const initCodePerScope = new Map();
		for (const chunk of /** @type {Chunk} */ (
			this.chunk
		).getAllReferencedChunks()) {
			const modules = chunkGraph.getOrderedChunkModulesIterableBySourceType(
				chunk,
				"share-init",
				compareModulesByIdentifier
			);
			if (!modules) continue;
			for (const m of modules) {
				const data = codeGenerationResults.getData(
					m,
					chunk.runtime,
					"share-init"
				);
				if (!data) continue;
				for (const item of data) {
					const { shareScope, initStage, init } = item;
					let stages = initCodePerScope.get(shareScope);
					if (stages === undefined) {
						initCodePerScope.set(shareScope, (stages = new Map()));
					}
					let list = stages.get(initStage || 0);
					if (list === undefined) {
						stages.set(initStage || 0, (list = new Set()));
					}
					list.add(init);
				}
			}
		}
		const cst = runtimeTemplate.renderConst();
		const lt = runtimeTemplate.renderLet();
		return Template.asString([
			`${RuntimeGlobals.shareScopeMap} = {};`,
			`${cst} initPromises = {};`,
			`${cst} initTokens = {};`,
			`${RuntimeGlobals.initializeSharing} = ${runtimeTemplate.basicFunction(
				"name, initScope",
				[
					"if(!initScope) initScope = [];",
					"// handling circular init calls",
					`${lt} initToken = initTokens[name];`,
					"if(!initToken) initToken = initTokens[name] = {};",
					"if(initScope.indexOf(initToken) >= 0) return;",
					"initScope.push(initToken);",
					"// only runs once",
					"if(initPromises[name]) return initPromises[name];",
					"// creates a new share scope if needed",
					`if(!${RuntimeGlobals.hasOwnProperty}(${RuntimeGlobals.shareScopeMap}, name)) ${RuntimeGlobals.shareScopeMap}[name] = {};`,
					"// runs all init snippets from all modules reachable",
					`${cst} scope = ${RuntimeGlobals.shareScopeMap}[name];`,
					`${cst} warn = ${
						ignoreBrowserWarnings
							? runtimeTemplate.basicFunction("", "")
							: runtimeTemplate.basicFunction("msg", [
									'if (typeof console !== "undefined" && console.warn) console.warn(msg);'
								])
					};`,
					`${cst} uniqueName = ${JSON.stringify(uniqueName || undefined)};`,
					`${cst} register = ${runtimeTemplate.basicFunction(
						"name, version, factory, eager",
						[
							`${cst} versions = ${runtimeTemplate.assignOr("scope[name]", "{}")};`,
							`${cst} activeVersion = versions[version];`,
							"if(!activeVersion || (!activeVersion.loaded && (!eager != !activeVersion.eager ? eager : uniqueName > activeVersion.from))) versions[version] = { get: factory, from: uniqueName, eager: !!eager };"
						]
					)};`,
					`${cst} initExternal = ${runtimeTemplate.basicFunction("id", [
						`${cst} handleError = ${runtimeTemplate.expressionFunction(
							'warn("Initialization of sharing external failed: " + err)',
							"err"
						)};`,
						"try {",
						Template.indent([
							`${cst} module = ${RuntimeGlobals.require}(id);`,
							"if(!module) return;",
							`${cst} initFn = ${runtimeTemplate.returningFunction(
								`module && module.init && module.init(${RuntimeGlobals.shareScopeMap}[name], initScope)`,
								"module"
							)}`,
							"if(module.then) return promises.push(module.then(initFn, handleError));",
							`${cst} initResult = initFn(module);`,
							`if(${runtimeTemplate.optionalChaining("initResult", "then")}) return promises.push(initResult['catch'](handleError));`
						]),
						"} catch(err) { handleError(err); }"
					])}`,
					`${cst} promises = [];`,
					"switch(name) {",
					...[...initCodePerScope]
						.sort(([a], [b]) => compareStrings(a, b))
						.map(([name, stages]) =>
							Template.indent([
								`case ${JSON.stringify(name)}: {`,
								Template.indent(
									[...stages]
										.sort(([a], [b]) => a - b)
										.map(([, initCode]) => Template.asString([...initCode]))
								),
								"}",
								"break;"
							])
						),
					"}",
					"if(!promises.length) return initPromises[name] = 1;",
					`return initPromises[name] = Promise.all(promises).then(${runtimeTemplate.returningFunction(
						"initPromises[name] = 1"
					)});`
				]
			)};`
		]);
	}
}

module.exports = ShareRuntimeModule;