feat(cargo): use cargo to build rust into wasm

㊙️ under the hood, it use rust-native-wasm-loader
✍️ use $Shape to relax Options type
👫 partially polyfill webpack specific context

[ci skip]

Author: DrSensor

flow-typed/rollupPluginRustDef.js

@@ -1,5 +1,7 @@
 declare type Options = {
+  target: string,
+  release: boolean,
   export: 'buffer' | 'instance' | 'module' | 'promise',
-  include?: string[] | string, // rollup recommend to add this
-  exclude?: string[] | string // rollup recommend to add this
+  include: string[] | string, // rollup recommend to add this
+  exclude: string[] | string // rollup recommend to add this
 };

package-lock.json

@@ -72,6 +72,7 @@
 		"rollup-plugin-eslint": "^5.0.0",
 		"rollup-plugin-node-resolve": "^3.3.0",
 		"rollup-plugin-prettier": "^0.4.0",
+		"rust-native-wasm-loader": "^0.8.1",
 		"standard-version": "^4.4.0"
 	},
 	"lint-staged": {

package.json

@@ -1,30 +1,47 @@
 // @flow
 import { createFilter } from 'rollup-pluginutils';
+import { readFileSync } from 'fs';
+import {
+  cargoCommand,
+  findSrcDir,
+  handleCargo
+} from 'rust-native-wasm-loader/dist/cargo';
+import { rollPack, execPermissive } from './util';
 import wrap from './wrapper';
 import predef from './options';
 
 const extension = /\.rs$/; // rust file extension
 
-export default function(options: Options = predef) {
-  options = Object.assign(predef, options); // diff and merge with predefined options
+export default function(options: $Shape<Options> = {}) {
+  options = (Object.assign(predef, options): Options); // diff and merge with predefined options
   const filter = createFilter(options.include, options.exclude);
+  const cmd = cargoCommand(options.target, options.release);
 
   return {
     name: 'rust',
     async transform(code: string, id: string) {
       if (!extension.test(id)) return;
       if (!filter(id)) return;
 
-      const wasmCode = Buffer.from([0x00, 0x61, 0x73, 0x6d, 0x01, 0, 0, 0]);
-      switch (options.export) {
-        case 'buffer':
-          return wrap(wasmCode).asBuffer;
-        case 'instance':
-          return wrap(wasmCode).asWebAssembly.Instance;
-        case 'module':
-          return wrap(wasmCode).asWebAssembly.Module;
-        case 'promise':
-          return wrap(wasmCode).promiseWebAssembly;
+      const cwd = await findSrcDir(id);
+      if (!cwd) this.error('No Cargo.toml file found in any parent directory.');
+      const result = await execPermissive(cmd, cwd);
+
+      if (options.target.includes('wasm')) {
+        let { wasmFile } = await handleCargo(rollPack(this).toLoader, result);
+        if (!wasmFile) this.error('No wasm file produced as build output');
+        const wasmCode = readFileSync(wasmFile);
+
+        switch (options.export) {
+          case 'buffer':
+            return wrap(wasmCode).asBuffer;
+          case 'instance':
+            return wrap(wasmCode).asWebAssembly.Instance;
+          case 'module':
+            return wrap(wasmCode).asWebAssembly.Module;
+          case 'promise':
+            return wrap(wasmCode).promiseWebAssembly;
+        }
       }
     }
   };

src/main.js

@@ -1,6 +1,8 @@
 // @flow
 /** Default options */
 export default ({
+  target: 'wasm32-unknown-uknown',
+  release: true,
   export: 'promise',
   include: ['**/*.rs'],
   exclude: ['node_modules/**', 'target/**']

src/options.js

@@ -0,0 +1,33 @@
+// @flow
+import { promisify } from 'util';
+import { exec } from 'child_process';
+
+/** Execute command in permissive environment
+ * @param cmd command to execute
+ * @param cwd working directory where the command executed
+ */
+export async function execPermissive(cmd: string, cwd: string) {
+  try {
+    return await promisify(exec)(cmd, {
+      cwd,
+      encoding: 'utf-8',
+      maxBuffer: 2 * 1024 * 1024 * 1024
+    });
+  } catch (error) {
+    return error;
+  }
+}
+/** Transform rollup plugin context into webpack specific context
+ * @param self rollup plugin context
+ * @see https://github.com/rollup/rollup/wiki/Plugins#plugin-context
+ */
+export function rollPack(self: any) {
+  return {
+    /** @see https://webpack.js.org/api/loaders/#the-loader-context */
+    toLoader: {
+      emitWarning: (warning: string | Error) => self.warning(warning),
+      emitError: (error: string | Error) => self.error(error),
+      addDependency: (file: string) => (file ? undefined : undefined)
+    }
+  };
+}