webpack/lib/wasm/AsyncWebAssemblyParser.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports 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
	Author Tobias Koppers @sokra
*/

"use strict";

const t = require("@webassemblyjs/ast");
const { decode } = require("@webassemblyjs/wasm-parser");
const StaticExportsDependency = require("../dependencies/core/StaticExportsDependency");
const WebAssemblyImportDependency = require("../dependencies/wasm/WebAssemblyImportDependency");
const Parser = require("../module/Parser");
const memoize = require("../util/memoize");

const getEnvironmentNotSupportAsyncWarning = memoize(() =>
	require("../errors/EnvironmentNotSupportAsyncWarning")
);

/** @import AsyncWasmModule, { BuiltAsyncWasmModule } from "./AsyncWasmModule" */
/** @import { ParserState, PreparsedAst } from "../module/Parser" */

const WASM_HEADER = Buffer.from([0x00, 0x61, 0x73, 0x6d]);

const decoderOpts = {
	ignoreCodeSection: true,
	ignoreDataSection: true,

	// this will avoid having to lookup with identifiers in the ModuleContext
	ignoreCustomNameSection: true
};

/**
 * @extends {Parser<BuiltAsyncWasmModule>}
 */
class AsyncWebAssemblyParser extends Parser {
	/**
	 * Parses the provided source and updates the parser state.
	 * @param {string | Buffer | PreparsedAst} source the source to parse
	 * @param {ParserState} state the parser state
	 * @returns {ParserState} the parser state
	 */
	parse(source, state) {
		if (!Buffer.isBuffer(source)) {
			throw new Error("AsyncWebAssemblyParser input must be a Buffer");
		}

		const { buildInfo, buildMeta } = /** @type {BuiltAsyncWasmModule} */ (
			state.module
		);
		buildMeta.exportsType = "namespace";
		buildMeta.async = true;

		getEnvironmentNotSupportAsyncWarning().check(
			state.module,
			state.compilation.runtimeTemplate,
			"asyncWebAssembly"
		);

		// flag it as async module
		buildInfo.strict = true;

		if (/** @type {AsyncWasmModule} */ (state.module).phase === "source") {
			// For source phase, only validate magic header
			if (source.length < 4 || !source.subarray(0, 4).equals(WASM_HEADER)) {
				throw new Error(
					"Source phase imports require valid WebAssembly modules. Invalid magic header (expected \\0asm)."
				);
			}

			// Source phase exports the WebAssembly.Module as default
			state.module.addDependency(
				new StaticExportsDependency(["default"], false)
			);

			// Skip full parsing - no exports/imports needed for source phase
			return state;
		}

		// parse it
		const program = decode(source, decoderOpts);
		const module = program.body[0];
		/** @type {string[]} */
		const exports = [];

		t.traverse(module, {
			ModuleExport({ node }) {
				exports.push(node.name);
			},

			ModuleImport({ node }) {
				const dep = new WebAssemblyImportDependency(
					node.module,
					node.name,
					node.descr,
					false
				);

				state.module.addDependency(dep);
			}
		});

		state.module.addDependency(new StaticExportsDependency(exports, false));

		return state;
	}
}

module.exports = AsyncWebAssemblyParser;