- Implement resource loading via the Resource class.

runtime/lib/resource_patch.dart

Index: runtime/lib/resource_patch.dart
diff --git a/runtime/lib/resource_patch.dart b/runtime/lib/resource_patch.dart
new file mode 100644
index 0000000000000000000000000000000000000000..0643516881ba6b5b7b355cc0ec81ba41a7b43249
--- /dev/null
+++ b/runtime/lib/resource_patch.dart
@@ -0,0 +1,68 @@
+// Copyright (c) 2015, 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.
+
+patch class Resource {
+  /* patch */ const factory Resource(String uri) = _Resource;
+}
+
+class _Resource implements Resource {
+  final String _location;
+
+  const _Resource(this._location);
+
+  Uri get uri => Uri.base.resolve(_location);
+
+  Stream<List<int>> openRead() {
+    if (VMLibraryHooks.resourceReadAsBytes == null) {
+      throw new UnimplementedError("openRead");
+    }
+
+    var controller = new StreamController<List<int>>();
+    // We only need to implement the listener as there is no way to provide
+    // back pressure into the channel.
+    controller.onListen = () {
+      // Once there is a listener, we kick off the loading of the resource.
+      readAsBytes().then((value) {
+        // The resource loading implementation sends all of the data in a
+        // single message. So the stream will only get a single value posted.
+        controller.add(value);
+        controller.close();
+      },
+      onError: (e, s) {
+        // In case the future terminates with an error we propagate it to the
+        // stream.
+        controller.addError(e, s);
+        controller.close();
+      });
+    };
+
+    return controller.stream;
+  }
+
+  Future<List<int>> readAsBytes() {
+    if (VMLibraryHooks.resourceReadAsBytes == null) {
+      throw new UnimplementedError("readAsBytes");
+    }
+
+    return VMLibraryHooks.resourceReadAsBytes(this.uri);
+  }
+
+  Future<String> readAsString({Encoding encoding : UTF8}) {
+    if (VMLibraryHooks.resourceReadAsBytes == null) {
+      throw new UnimplementedError("readAsString");
+    }
+
+    var completer = new Completer<String>();
+
+    readAsBytes().then((bytes) {
+      var str = encoding.decode(bytes);
+      completer.complete(str);
+    },
+    onError: (e, s) {
+      completer.completeError(e,s);
+    });
+
+    return completer.future;
+  }
+}