webpack/lib/runtime/AsyncModuleRuntimeModule.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
*/

"use strict";

const RuntimeGlobals = require("../RuntimeGlobals");
const Template = require("../Template");
const HelperRuntimeModule = require("./HelperRuntimeModule");

class AsyncModuleRuntimeModule extends HelperRuntimeModule {
	constructor() {
		super("async module");
	}

	/**
	 * @returns {string} runtime code
	 */
	generate() {
		const { runtimeTemplate } = this.compilation;
		const fn = RuntimeGlobals.asyncModule;
		return Template.asString([
			'var webpackThen = typeof Symbol === "function" ? Symbol("webpack then") : "__webpack_then__";',
			'var webpackExports = typeof Symbol === "function" ? Symbol("webpack exports") : "__webpack_exports__";',
			`var completeQueue = ${runtimeTemplate.basicFunction("queue", [
				"if(queue) {",
				Template.indent([
					`queue.forEach(${runtimeTemplate.expressionFunction(
						"fn.r--",
						"fn"
					)});`,
					`queue.forEach(${runtimeTemplate.expressionFunction(
						"fn.r-- ? fn.r++ : fn()",
						"fn"
					)});`
				]),
				"}"
			])}`,
			`var completeFunction = ${runtimeTemplate.expressionFunction(
				"!--fn.r && fn()",
				"fn"
			)};`,
			`var queueFunction = ${runtimeTemplate.expressionFunction(
				"queue ? queue.push(fn) : completeFunction(fn)",
				"queue, fn"
			)};`,
			`var wrapDeps = ${runtimeTemplate.returningFunction(
				`deps.map(${runtimeTemplate.basicFunction("dep", [
					'if(dep !== null && typeof dep === "object") {',
					Template.indent([
						"if(dep[webpackThen]) return dep;",
						"if(dep.then) {",
						Template.indent([
							"var queue = [];",
							`dep.then(${runtimeTemplate.basicFunction("r", [
								"obj[webpackExports] = r;",
								"completeQueue(queue);",
								"queue = 0;"
							])});`,
							`var obj = {};
							obj[webpackThen] = ${runtimeTemplate.expressionFunction(
								"queueFunction(queue, fn), dep['catch'](reject)",
								"fn, reject"
							)};`,
							"return obj;"
						]),
						"}"
					]),
					"}",
					`var ret = {};
					ret[webpackThen] = ${runtimeTemplate.expressionFunction(
						"completeFunction(fn)",
						"fn"
					)};
					ret[webpackExports] = dep;
					return ret;`
				])})`,
				"deps"
			)};`,
			`${fn} = ${runtimeTemplate.basicFunction("module, body, hasAwait", [
				"var queue = hasAwait && [];",
				"var exports = module.exports;",
				"var currentDeps;",
				"var outerResolve;",
				"var reject;",
				"var isEvaluating = true;",
				"var nested = false;",
				`var whenAll = ${runtimeTemplate.basicFunction(
					"deps, onResolve, onReject",
					[
						"if (nested) return;",
						"nested = true;",
						"onResolve.r += deps.length;",
						`deps.map(${runtimeTemplate.expressionFunction(
							"dep[webpackThen](onResolve, onReject)",
							"dep, i"
						)});`,
						"nested = false;"
					]
				)};`,
				`var promise = new Promise(${runtimeTemplate.basicFunction(
					"resolve, rej",
					[
						"reject = rej;",
						`outerResolve = ${runtimeTemplate.expressionFunction(
							"resolve(exports), completeQueue(queue), queue = 0"
						)};`
					]
				)});`,
				"promise[webpackExports] = exports;",
				`promise[webpackThen] = ${runtimeTemplate.basicFunction(
					"fn, rejectFn",
					[
						"if (isEvaluating) { return completeFunction(fn); }",
						"if (currentDeps) whenAll(currentDeps, fn, rejectFn);",
						"queueFunction(queue, fn);",
						"promise['catch'](rejectFn);"
					]
				)};`,
				"module.exports = promise;",
				`body(${runtimeTemplate.basicFunction("deps", [
					"if(!deps) return outerResolve();",
					"currentDeps = wrapDeps(deps);",
					"var fn, result;",
					`var promise = new Promise(${runtimeTemplate.basicFunction(
						"resolve, reject",
						[
							`fn = ${runtimeTemplate.expressionFunction(
								`resolve(result = currentDeps.map(${runtimeTemplate.returningFunction(
									"d[webpackExports]",
									"d"
								)}))`
							)};`,
							"fn.r = 0;",
							"whenAll(currentDeps, fn, reject);"
						]
					)});`,
					"return fn.r ? promise : result;"
				])}).then(outerResolve, reject);`,
				"isEvaluating = false;"
			])};`
		]);
	}
}

module.exports = AsyncModuleRuntimeModule;