source: frontend/node_modules/webpack/lib/wasm-async/AsyncWasmLoadingRuntimeModule.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");

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

/** @typedef {(wasmModuleSrcPath: string) => string} GenerateBeforeLoadBinaryCode */
/** @typedef {(wasmModuleSrcPath: string) => string} GenerateLoadBinaryCode */
/** @typedef {() => string} GenerateBeforeInstantiateStreaming */

/**
 * @typedef {object} AsyncWasmLoadingRuntimeModuleOptions
 * @property {GenerateLoadBinaryCode} generateLoadBinaryCode
 * @property {GenerateBeforeLoadBinaryCode=} generateBeforeLoadBinaryCode
 * @property {GenerateBeforeInstantiateStreaming=} generateBeforeInstantiateStreaming
 * @property {boolean} supportsStreaming
 */

class AsyncWasmLoadingRuntimeModule extends RuntimeModule {
        /**
         * @param {AsyncWasmLoadingRuntimeModuleOptions} options options
         */
        constructor({
                generateLoadBinaryCode,
                generateBeforeLoadBinaryCode,
                generateBeforeInstantiateStreaming,
                supportsStreaming
        }) {
                super("wasm loading", RuntimeModule.STAGE_NORMAL);
                /** @type {GenerateLoadBinaryCode} */
                this.generateLoadBinaryCode = generateLoadBinaryCode;
                /** @type {generateBeforeLoadBinaryCode | undefined} */
                this.generateBeforeLoadBinaryCode = generateBeforeLoadBinaryCode;
                /** @type {generateBeforeInstantiateStreaming | undefined} */
                this.generateBeforeInstantiateStreaming =
                        generateBeforeInstantiateStreaming;
                /** @type {boolean} */
                this.supportsStreaming = supportsStreaming;
        }

        /**
         * Generates runtime code for this runtime module.
         * @returns {string | null} runtime code
         */
        generate() {
                const compilation = /** @type {Compilation} */ (this.compilation);
                const chunk = /** @type {Chunk} */ (this.chunk);
                const { outputOptions, runtimeTemplate } = compilation;
                const fn = RuntimeGlobals.instantiateWasm;
                const wasmModuleSrcPath = compilation.getPath(
                        JSON.stringify(outputOptions.webassemblyModuleFilename),
                        {
                                hash: `" + ${RuntimeGlobals.getFullHash}() + "`,
                                hashWithLength: (length) =>
                                        `" + ${RuntimeGlobals.getFullHash}}().slice(0, ${length}) + "`,
                                module: {
                                        id: '" + wasmModuleId + "',
                                        hash: '" + wasmModuleHash + "',
                                        hashWithLength(length) {
                                                return `" + wasmModuleHash.slice(0, ${length}) + "`;
                                        }
                                },
                                runtime: chunk.runtime
                        }
                );

                const loader = this.generateLoadBinaryCode(wasmModuleSrcPath);
                const fallback = [
                        `.then(${runtimeTemplate.returningFunction("x.arrayBuffer()", "x")})`,
                        `.then(${runtimeTemplate.returningFunction(
                                "WebAssembly.instantiate(bytes, importsObj)",
                                "bytes"
                        )})`,
                        `.then(${runtimeTemplate.returningFunction(
                                "Object.assign(exports, res.instance.exports)",
                                "res"
                        )})`
                ];
                const getStreaming = () => {
                        /**
                         * @param {string[]} text text
                         * @returns {string} merged text
                         */
                        const concat = (...text) => text.join("");
                        return [
                                this.generateBeforeLoadBinaryCode
                                        ? this.generateBeforeLoadBinaryCode(wasmModuleSrcPath)
                                        : "",
                                `var req = ${loader};`,
                                `var fallback = ${runtimeTemplate.returningFunction(
                                        Template.asString(["req", Template.indent(fallback)])
                                )};`,
                                concat(
                                        "return req.then(",
                                        runtimeTemplate.basicFunction("res", [
                                                'if (typeof WebAssembly.instantiateStreaming === "function") {',
                                                Template.indent(
                                                        this.generateBeforeInstantiateStreaming
                                                                ? this.generateBeforeInstantiateStreaming()
                                                                : ""
                                                ),
                                                Template.indent([
                                                        "return WebAssembly.instantiateStreaming(res, importsObj)",
                                                        Template.indent([
                                                                ".then(",
                                                                Template.indent([
                                                                        `${runtimeTemplate.returningFunction(
                                                                                "Object.assign(exports, res.instance.exports)",
                                                                                "res"
                                                                        )},`,
                                                                        runtimeTemplate.basicFunction("e", [
                                                                                'if(res.headers.get("Content-Type") !== "application/wasm") {',
                                                                                Template.indent([
                                                                                        'console.warn("`WebAssembly.instantiateStreaming` failed because your server does not serve wasm with `application/wasm` MIME type. Falling back to `WebAssembly.instantiate` which is slower. Original error:\\n", e);',
                                                                                        "return fallback();"
                                                                                ]),
                                                                                "}",
                                                                                "throw e;"
                                                                        ])
                                                                ]),
                                                                ");"
                                                        ])
                                                ]),
                                                "}",
                                                "return fallback();"
                                        ]),
                                        ");"
                                )
                        ];
                };

                return `${fn} = ${runtimeTemplate.basicFunction(
                        "exports, wasmModuleId, wasmModuleHash, importsObj",
                        this.supportsStreaming
                                ? getStreaming()
                                : [
                                                this.generateBeforeLoadBinaryCode
                                                        ? this.generateBeforeLoadBinaryCode(wasmModuleSrcPath)
                                                        : "",
                                                `return ${loader}`,
                                                `${Template.indent(fallback)};`
                                        ]
                )};`;
        }
}

module.exports = AsyncWasmLoadingRuntimeModule;