Async compilation and instantiation (#62)

* Async compilation and instantiation

* Fix analysis error

Author: liamappelbe

wasm/CHANGELOG.md

@@ -6,6 +6,8 @@
 - Add options to setup.dart for configuring the build.
 - Add Module.serialize and Module.deserialize.
 - Add bin/precompile.dart, which compiles and serializes wasm modules.
+- Add `WasmModule.compileAsync` and `WasmInstanceBuilder.buildAsync`, so that
+  the web API can be supported in the future.
 
 ## 0.1.0+1
 

wasm/lib/src/module.dart

@@ -21,6 +21,10 @@ class WasmModule {
   /// Deserialize a module. See [WasmModule.serialize] for more details.
   WasmModule.deserialize(Uint8List data) : this._(data, true);
 
+  /// Asynchronously compile a module.
+  static Future<WasmModule> compileAsync(Uint8List data) async =>
+      Future<WasmModule>(() => WasmModule(data));
+
   /// Returns a [WasmInstanceBuilder] that is used to add all the imports that
   /// the module needs before instantiating it.
   WasmInstanceBuilder builder() => WasmInstanceBuilder._(this);
@@ -223,6 +227,9 @@ class WasmInstanceBuilder {
     }
     return WasmInstance._(_module, _importOwner, _imports, _wasiEnv);
   }
+
+  /// Asynchronously build the module instance.
+  Future<WasmInstance> buildAsync() async => Future<WasmInstance>(build);
 }
 
 // TODO: should not be required once the min supported Dart SDK includes

wasm/test/async_test.dart

@@ -0,0 +1,33 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Test that we can load a wasm module, find a function, and call it.
+import 'dart:typed_data';
+
+import 'package:test/test.dart';
+import 'package:wasm/wasm.dart';
+
+void main() {
+  test('async compilation', () async {
+    // int64_t square(int64_t n) { return n * n; }
+    final data = Uint8List.fromList([
+      0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00, 0x01, 0x06, 0x01, 0x60, //
+      0x01, 0x7e, 0x01, 0x7e, 0x03, 0x02, 0x01, 0x00, 0x04, 0x05, 0x01, 0x70,
+      0x01, 0x01, 0x01, 0x05, 0x03, 0x01, 0x00, 0x02, 0x06, 0x08, 0x01, 0x7f,
+      0x01, 0x41, 0x80, 0x88, 0x04, 0x0b, 0x07, 0x13, 0x02, 0x06, 0x6d, 0x65,
+      0x6d, 0x6f, 0x72, 0x79, 0x02, 0x00, 0x06, 0x73, 0x71, 0x75, 0x61, 0x72,
+      0x65, 0x00, 0x00, 0x0a, 0x09, 0x01, 0x07, 0x00, 0x20, 0x00, 0x20, 0x00,
+      0x7e, 0x0b,
+    ]);
+
+    final mod = await WasmModule.compileAsync(data);
+    final inst = await mod.builder().buildAsync();
+    final fn = inst.lookupFunction('square');
+    final n = fn(1234) as int;
+
+    expect(n, 1234 * 1234);
+
+    expect(inst.lookupFunction('not_a_function'), isNull);
+  });
+}