webpack/lib/wasm-async/AsyncWebAssemblyParser.js

Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support 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 Parser = require("../Parser");
const StaticExportsDependency = require("../dependencies/StaticExportsDependency");
const WebAssemblyImportDependency = require("../dependencies/WebAssemblyImportDependency");

/** @typedef {import("../Parser").ParserState} ParserState */
/** @typedef {import("../Parser").PreparsedAst} PreparsedAst */

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

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

class WebAssemblyParser extends Parser {
	constructor(options) {
		super();
		this.hooks = Object.freeze({});
		this.options = options;
	}

	/**
	 * @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("WebAssemblyParser input must be a Buffer");
		}

		// flag it as async module
		state.module.buildInfo.strict = true;
		state.module.buildMeta.exportsType = "namespace";
		state.module.buildMeta.async = true;

		// parse it
		const program = decode(source, decoderOpts);
		const module = program.body[0];

		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 = WebAssemblyParser;