source: frontend/node_modules/webpack/lib/container/FallbackModule.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra and Zackary Jackson @ScriptedAlchemy
*/

"use strict";

const { RawSource } = require("webpack-sources");
const Module = require("../Module");
const {
        JAVASCRIPT_TYPE,
        JAVASCRIPT_TYPES
} = require("../ModuleSourceTypeConstants");
const { WEBPACK_MODULE_TYPE_FALLBACK } = require("../ModuleTypeConstants");
const RuntimeGlobals = require("../RuntimeGlobals");
const Template = require("../Template");
const makeSerializable = require("../util/makeSerializable");
const FallbackItemDependency = require("./FallbackItemDependency");

/** @typedef {import("../config/defaults").WebpackOptionsNormalizedWithDefaults} WebpackOptions */
/** @typedef {import("../Chunk")} Chunk */
/** @typedef {import("../Compilation")} Compilation */
/** @typedef {import("../Module").BuildCallback} BuildCallback */
/** @typedef {import("../Module").CodeGenerationContext} CodeGenerationContext */
/** @typedef {import("../Module").CodeGenerationResult} CodeGenerationResult */
/** @typedef {import("../Module").LibIdentOptions} LibIdentOptions */
/** @typedef {import("../Module").LibIdent} LibIdent */
/** @typedef {import("../Module").NameForCondition} NameForCondition */
/** @typedef {import("../Module").NeedBuildCallback} NeedBuildCallback */
/** @typedef {import("../Module").NeedBuildContext} NeedBuildContext */
/** @typedef {import("../Module").Sources} Sources */
/** @typedef {import("../Module").SourceTypes} SourceTypes */
/** @typedef {import("../RequestShortener")} RequestShortener */
/** @typedef {import("../ResolverFactory").ResolverWithOptions} ResolverWithOptions */
/** @typedef {import("../serialization/ObjectMiddleware").ObjectDeserializerContext} ObjectDeserializerContext */
/** @typedef {import("../serialization/ObjectMiddleware").ObjectSerializerContext} ObjectSerializerContext */
/** @typedef {import("../util/fs").InputFileSystem} InputFileSystem */
/** @typedef {import("./RemoteModule").ExternalRequests} ExternalRequests */

const RUNTIME_REQUIREMENTS = new Set([RuntimeGlobals.module]);

class FallbackModule extends Module {
        /**
         * Creates an instance of FallbackModule.
         * @param {ExternalRequests} requests list of requests to choose one
         */
        constructor(requests) {
                super(WEBPACK_MODULE_TYPE_FALLBACK);
                /** @type {ExternalRequests} */
                this.requests = requests;
                /** @type {string} */
                this._identifier = `fallback ${this.requests.join(" ")}`;
        }

        /**
         * Returns the unique identifier used to reference this module.
         * @returns {string} a unique identifier of the module
         */
        identifier() {
                return this._identifier;
        }

        /**
         * Returns a human-readable identifier for this module.
         * @param {RequestShortener} requestShortener the request shortener
         * @returns {string} a user readable identifier of the module
         */
        readableIdentifier(requestShortener) {
                return this._identifier;
        }

        /**
         * Gets the library identifier.
         * @param {LibIdentOptions} options options
         * @returns {LibIdent | null} an identifier for library inclusion
         */
        libIdent(options) {
                return `${this.layer ? `(${this.layer})/` : ""}webpack/container/fallback/${
                        this.requests[0]
                }/and ${this.requests.length - 1} more`;
        }

        /**
         * Returns true if the module can be placed in the chunk.
         * @param {Chunk} chunk the chunk which condition should be checked
         * @param {Compilation} compilation the compilation
         * @returns {boolean} true if the module can be placed in the chunk
         */
        chunkCondition(chunk, { chunkGraph }) {
                return chunkGraph.getNumberOfEntryModules(chunk) > 0;
        }

        /**
         * Checks whether the module needs to be rebuilt for the current build state.
         * @param {NeedBuildContext} context context info
         * @param {NeedBuildCallback} callback callback function, returns true, if the module needs a rebuild
         * @returns {void}
         */
        needBuild(context, callback) {
                callback(null, !this.buildInfo);
        }

        /**
         * Builds the module using the provided compilation context.
         * @param {WebpackOptions} options webpack options
         * @param {Compilation} compilation the compilation
         * @param {ResolverWithOptions} resolver the resolver
         * @param {InputFileSystem} fs the file system
         * @param {BuildCallback} callback callback function
         * @returns {void}
         */
        build(options, compilation, resolver, fs, callback) {
                this.buildMeta = {};
                this.buildInfo = {
                        strict: true
                };

                this.clearDependenciesAndBlocks();
                for (const request of this.requests) {
                        this.addDependency(new FallbackItemDependency(request));
                }

                callback();
        }

        /**
         * Returns the estimated size for the requested source type.
         * @param {string=} type the source type for which the size should be estimated
         * @returns {number} the estimated size of the module (must be non-zero)
         */
        size(type) {
                return this.requests.length * 5 + 42;
        }

        /**
         * Returns the source types this module can generate.
         * @returns {SourceTypes} types available (do not mutate)
         */
        getSourceTypes() {
                return JAVASCRIPT_TYPES;
        }

        /**
         * Generates code and runtime requirements for this module.
         * @param {CodeGenerationContext} context context for code generation
         * @returns {CodeGenerationResult} result
         */
        codeGeneration({ runtimeTemplate, moduleGraph, chunkGraph }) {
                const ids = this.dependencies.map((dep) =>
                        chunkGraph.getModuleId(/** @type {Module} */ (moduleGraph.getModule(dep)))
                );
                const code = Template.asString([
                        `var ids = ${JSON.stringify(ids)};`,
                        "var error, result, i = 0;",
                        `var loop = ${runtimeTemplate.basicFunction("next", [
                                "while(i < ids.length) {",
                                Template.indent([
                                        `try { next = ${RuntimeGlobals.require}(ids[i++]); } catch(e) { return handleError(e); }`,
                                        "if(next) return next.then ? next.then(handleResult, handleError) : handleResult(next);"
                                ]),
                                "}",
                                "if(error) throw error;"
                        ])}`,
                        `var handleResult = ${runtimeTemplate.basicFunction("result", [
                                "if(result) return result;",
                                "return loop();"
                        ])};`,
                        `var handleError = ${runtimeTemplate.basicFunction("e", [
                                "error = e;",
                                "return loop();"
                        ])};`,
                        "module.exports = loop();"
                ]);
                /** @type {Sources} */
                const sources = new Map();
                sources.set(JAVASCRIPT_TYPE, new RawSource(code));
                return { sources, runtimeRequirements: RUNTIME_REQUIREMENTS };
        }

        /**
         * Serializes this instance into the provided serializer context.
         * @param {ObjectSerializerContext} context context
         */
        serialize(context) {
                const { write } = context;
                write(this.requests);
                super.serialize(context);
        }

        /**
         * Restores this instance from the provided deserializer context.
         * @param {ObjectDeserializerContext} context context
         * @returns {FallbackModule} deserialized fallback module
         */
        static deserialize(context) {
                const { read } = context;
                const obj = new FallbackModule(read());
                obj.deserialize(context);
                return obj;
        }
}

makeSerializable(FallbackModule, "webpack/lib/container/FallbackModule");

module.exports = FallbackModule;