source: frontend/node_modules/webpack/lib/web/FetchCompileAsyncWasmPlugin.js

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

"use strict";

const { WEBASSEMBLY_MODULE_TYPE_ASYNC } = require("../ModuleTypeConstants");
const RuntimeGlobals = require("../RuntimeGlobals");
const AsyncWasmCompileRuntimeModule = require("../wasm-async/AsyncWasmCompileRuntimeModule");
const AsyncWasmLoadingRuntimeModule = require("../wasm-async/AsyncWasmLoadingRuntimeModule");

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

const PLUGIN_NAME = "FetchCompileAsyncWasmPlugin";

/**
 * Enables asynchronous WebAssembly loading through `fetch` for environments
 * that can instantiate fetched binaries at runtime.
 */
class FetchCompileAsyncWasmPlugin {
        /**
         * Registers compilation hooks that attach the async fetch-based wasm runtime
         * to chunks containing async WebAssembly modules.
         * @param {Compiler} compiler the compiler instance
         * @returns {void}
         */
        apply(compiler) {
                compiler.hooks.thisCompilation.tap(PLUGIN_NAME, (compilation) => {
                        const globalWasmLoading = compilation.outputOptions.wasmLoading;
                        /**
                         * Determines whether the chunk should load async WebAssembly binaries
                         * through the `fetch` backend.
                         * @param {Chunk} chunk chunk
                         * @returns {boolean} true, if wasm loading is enabled for the chunk
                         */
                        const isEnabledForChunk = (chunk) => {
                                const options = chunk.getEntryOptions();
                                const wasmLoading =
                                        options && options.wasmLoading !== undefined
                                                ? options.wasmLoading
                                                : globalWasmLoading;
                                return wasmLoading === "fetch";
                        };
                        /**
                         * Generates the runtime expression that downloads the emitted wasm
                         * binary for an async WebAssembly module.
                         * @param {string} path path to the wasm file
                         * @returns {string} code to load the wasm file
                         */
                        const generateLoadBinaryCode = (path) =>
                                `fetch(${RuntimeGlobals.publicPath} + ${path})`;

                        compilation.hooks.runtimeRequirementInTree
                                .for(RuntimeGlobals.instantiateWasm)
                                .tap(PLUGIN_NAME, (chunk, set, { chunkGraph }) => {
                                        if (!isEnabledForChunk(chunk)) return;
                                        if (
                                                !chunkGraph.hasModuleInGraph(
                                                        chunk,
                                                        (m) => m.type === WEBASSEMBLY_MODULE_TYPE_ASYNC
                                                )
                                        ) {
                                                return;
                                        }
                                        set.add(RuntimeGlobals.publicPath);
                                        compilation.addRuntimeModule(
                                                chunk,
                                                new AsyncWasmLoadingRuntimeModule({
                                                        generateLoadBinaryCode,
                                                        supportsStreaming: true
                                                })
                                        );
                                });

                        compilation.hooks.runtimeRequirementInTree
                                .for(RuntimeGlobals.compileWasm)
                                .tap(PLUGIN_NAME, (chunk, set, { chunkGraph }) => {
                                        if (!isEnabledForChunk(chunk)) return;
                                        if (
                                                !chunkGraph.hasModuleInGraph(
                                                        chunk,
                                                        (m) => m.type === WEBASSEMBLY_MODULE_TYPE_ASYNC
                                                )
                                        ) {
                                                return;
                                        }
                                        set.add(RuntimeGlobals.publicPath);
                                        compilation.addRuntimeModule(
                                                chunk,
                                                new AsyncWasmCompileRuntimeModule({
                                                        generateLoadBinaryCode,
                                                        supportsStreaming: true
                                                })
                                        );
                                });
                });
        }
}

module.exports = FetchCompileAsyncWasmPlugin;