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

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

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

module.exports = ShareRuntimeModule;