source: frontend/node_modules/webpack/lib/sharing/ShareRuntimeModule.js

/*
        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);
                                }
                        }
                }
                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 = ${
                                                ignoreBrowserWarnings
                                                        ? runtimeTemplate.basicFunction("", "")
                                                        : runtimeTemplate.basicFunction("msg", [
                                                                        'if (typeof console !== "undefined" && console.warn) console.warn(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 = ${RuntimeGlobals.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) {",
                                        ...[...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;