webpack/lib/wasm/WebAssemblyJavascriptGenerator.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 Generator = require("../Generator");
const Template = require("../Template");
const { RawSource } = require("webpack-sources");
const WebAssemblyImportDependency = require("../dependencies/WebAssemblyImportDependency");
const WebAssemblyExportImportedDependency = require("../dependencies/WebAssemblyExportImportedDependency");

/** @typedef {import("../NormalModule")} NormalModule */
/** @typedef {import("../RuntimeTemplate")} RuntimeTemplate */
/** @typedef {import("webpack-sources").Source} Source */
/** @typedef {import("../Dependency").DependencyTemplate} DependencyTemplate */

class WebAssemblyJavascriptGenerator extends Generator {
	/**
	 * @param {NormalModule} module module for which the code should be generated
	 * @param {Map<Function, DependencyTemplate>} dependencyTemplates mapping from dependencies to templates
	 * @param {RuntimeTemplate} runtimeTemplate the runtime template
	 * @param {string} type which kind of code should be generated
	 * @returns {Source} generated code
	 */
	generate(module, dependencyTemplates, runtimeTemplate, type) {
		const initIdentifer = Array.isArray(module.usedExports)
			? Template.numberToIdentifer(module.usedExports.length)
			: "__webpack_init__";

		let needExportsCopy = false;
		const importedModules = new Map();
		const initParams = [];
		let index = 0;
		for (const dep of module.dependencies) {
			const depAsAny = /** @type {any} */ (dep);
			if (dep.module) {
				let importData = importedModules.get(dep.module);
				if (importData === undefined) {
					importedModules.set(
						dep.module,
						(importData = {
							importVar: `m${index}`,
							index,
							request:
								"userRequest" in depAsAny ? depAsAny.userRequest : undefined,
							names: new Set(),
							reexports: []
						})
					);
					index++;
				}
				if (dep instanceof WebAssemblyImportDependency) {
					importData.names.add(dep.name);
					if (dep.description.type === "GlobalType") {
						const exportName = dep.name;
						const usedName = dep.module && dep.module.isUsed(exportName);

						if (dep.module) {
							if (usedName) {
								initParams.push(
									runtimeTemplate.exportFromImport({
										module: dep.module,
										request: dep.request,
										importVar: importData.importVar,
										originModule: module,
										exportName: dep.name,
										asiSafe: true,
										isCall: false,
										callContext: null
									})
								);
							}
						}
					}
				}
				if (dep instanceof WebAssemblyExportImportedDependency) {
					importData.names.add(dep.name);
					const usedName = module.isUsed(dep.exportName);
					if (usedName) {
						const exportProp = `${module.exportsArgument}[${JSON.stringify(
							usedName
						)}]`;
						const defineStatement = Template.asString([
							`${exportProp} = ${runtimeTemplate.exportFromImport({
								module: dep.module,
								request: dep.request,
								importVar: importData.importVar,
								originModule: module,
								exportName: dep.name,
								asiSafe: true,
								isCall: false,
								callContext: null
							})};`,
							`if(WebAssembly.Global) ${exportProp} = ` +
								`new WebAssembly.Global({ value: ${JSON.stringify(
									dep.valueType
								)} }, ${exportProp});`
						]);
						importData.reexports.push(defineStatement);
						needExportsCopy = true;
					}
				}
			}
		}
		const importsCode = Template.asString(
			Array.from(
				importedModules,
				([module, { importVar, request, reexports }]) => {
					const importStatement = runtimeTemplate.importStatement({
						module,
						request,
						importVar,
						originModule: module
					});
					return importStatement + reexports.join("\n");
				}
			)
		);

		// create source
		const source = new RawSource(
			[
				'"use strict";',
				"// Instantiate WebAssembly module",
				"var wasmExports = __webpack_require__.w[module.i];",

				!Array.isArray(module.usedExports)
					? `__webpack_require__.r(${module.exportsArgument});`
					: "",

				// this must be before import for circular dependencies
				"// export exports from WebAssembly module",
				Array.isArray(module.usedExports) && !needExportsCopy
					? `${module.moduleArgument}.exports = wasmExports;`
					: "for(var name in wasmExports) " +
					  `if(name != ${JSON.stringify(initIdentifer)}) ` +
					  `${module.exportsArgument}[name] = wasmExports[name];`,
				"// exec imports from WebAssembly module (for esm order)",
				importsCode,
				"",
				"// exec wasm module",
				`wasmExports[${JSON.stringify(initIdentifer)}](${initParams.join(
					", "
				)})`
			].join("\n")
		);
		return source;
	}
}

module.exports = WebAssemblyJavascriptGenerator;