webpack/lib/wasm/WasmModuleTemplatePlugin.js

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

const RawSource = require("webpack-sources").RawSource;
const WebAssemblyImportDependency = require("../dependencies/WebAssemblyImportDependency");

class WasmModuleTemplatePlugin {
	apply(moduleTemplate) {
		moduleTemplate.hooks.content.tap("WasmModuleTemplatePlugin", (moduleSource, module, {
			chunk
		}) => {
			if(module.type && module.type.startsWith("webassembly")) {
				if(chunk.canBeInitial())
					throw new Error("Sync WebAssembly compilation is not yet implemented");
				const generateExports = () => {
					if(Array.isArray(module.buildMeta.providedExports) && Array.isArray(module.usedExports)) {
						// generate mangled exports
						return module.buildMeta.providedExports.map(exp => {
							const usedName = module.isUsed(exp);
							if(usedName) {
								return `${module.exportsArgument}[${JSON.stringify(usedName)}] = instance.exports[${JSON.stringify(exp)}];`;
							} else {
								return `// unused ${JSON.stringify(exp)} export`;
							}
						}).join("\n");
					} else {
						// generate simple export
						return `${module.moduleArgument}.exports = instance.exports;`;
					}
				};
				const generateImports = () => {
					const depsByRequest = new Map();
					for(const dep of module.dependencies) {
						if(dep instanceof WebAssemblyImportDependency) {
							const request = dep.request;
							let array = depsByRequest.get(request);
							if(!array) {
								depsByRequest.set(request, array = []);
							}
							const exportName = dep.name;
							const usedName = dep.module && dep.module.isUsed(exportName);
							array.push({
								exportName,
								usedName,
								module: dep.module
							});
						}
					}
					const importsCode = [];
					for(const pair of depsByRequest) {
						const properties = [];
						for(const data of pair[1]) {
							properties.push(`\n\t\t${JSON.stringify(data.exportName)}: __webpack_require__(${JSON.stringify(data.module.id)})[${JSON.stringify(data.usedName)}]`);
						}
						importsCode.push(`\n\t${JSON.stringify(pair[0])}: {${properties.join(",")}\n\t}`);
					}
					return importsCode.join(",");
				};
				const source = new RawSource([
					"\"use strict\";",
					"",
					"// Instantiate WebAssembly module",
					"var instance = new WebAssembly.Instance(__webpack_require__.w[module.i], {" + generateImports(),
					"});",
					"",
					"// export exports from WebAssembly module",
					// TODO rewrite this to getters depending on exports to support circular dependencies
					generateExports()
				].join("\n"));
				return source;
			} else {
				return moduleSource;
			}
		});

		moduleTemplate.hooks.hash.tap("WasmModuleTemplatePlugin", hash => {
			hash.update("WasmModuleTemplatePlugin");
			hash.update("1");
		});
	}
}
module.exports = WasmModuleTemplatePlugin;