Add browser-compatible version.

lib/src/browser/resource.dart

 // 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.
 
+/// A [Resource] is data that can be read into a Dart program.
+///
+/// A resource is identified by a URI. It can be loaded as bytes or data.

[floitsch, 2016/01/21 12:53:57]

"or string"?

[Lasse Reichstein Nielsen, 2016/01/25 10:48:37]

Done.

+/// The resource URI may be a `package:` URI.
+///
+/// Example:
+///
+///     var resource = new Resource("package:foo/foo_data.txt");
+///     var string = await resource.readAsString(UTF8);
+///     print(string);
+///
+/// Example:
+///
+///     var resource = new Resource("http://example.com/data.json");
+///     var obj = await resource.openRead()   // Reads as stream of bytes.
+///                             .transform(UTF8.fuse(JSON).decoder)
+///                             .first;
+///
+///
+/// Notice: Currently this package requires `dart:html` to do the reading,
+/// so it only works in the browser.
+library resource;
+
 import "dart:async" show Future, Stream;
-import "dart:convert" show Encoding;
-import "dart:isolate" show Isolate;
-import "loader.dart";
+
+import "loader.dart" show ResourceLoader;
+// TODO(lrn): Merge with implementation when configured imports removes
+// the need to share code.
+import "../resource_impl.dart" as impl show Resource;
 
 /// A resource that can be read into the program.
 ///
 /// A resource is data that can be located using a URI and read into
 /// the program at runtime.
 /// The URI may use the `package` scheme to read resources provided
 /// along with package sources.
-abstract class Resource {
+class Resource extends impl.Resource {
   /// Creates a resource object with the given [uri] as location.

[floitsch, 2016/01/21 12:53:57]

I would inherit these comments for both Resource-classes (web and io) from
impl.Resource.

[Lasse Reichstein Nielsen, 2016/01/25 10:48:37]

The constructor comment can't be inherited, but I'll move the other ones.

   ///
   /// The [uri] must be either a [Uri] or a string containing a valid URI.
   /// If the string is not a valid URI, using any of the functions on
   /// the resource object will fail.
   ///
   /// The URI may be relative, in which case it will be resolved
   /// against [Uri.base] before being used.
   ///
   /// The URI may use the `package` scheme, which is always supported.
   /// Other schemes may also be supported where possible.
   ///
   /// If [loader] is provided, it is used to load absolute non-package URIs.
   /// Package: URIs are resolved to a non-package URI before being loaded, so
   /// the loader doesn't have to support package: URIs, nor does it need to
   /// support relative URI references.
   /// If [loader] is omitted, a default implementation is used which supports
   /// as many of `http`, `https`, `file` and `data` as are available on the
   /// current platform.
-  const factory Resource(uri, {ResourceLoader loader}) = _Resource;
+  const Resource(uri, {ResourceLoader loader})
+      : super(uri, (loader != null) ? loader : const DefaultLoader());
 
   /// The location URI of this resource.
   ///
   /// This is a [Uri] of the `uri` parameter given to the constructor.
   /// If the parameter was a string that did not contain a valid URI,
   /// reading `uri` will fail.
   Uri get uri;
 
   /// Reads the resource content as a stream of bytes.
   Stream<List<int>> openRead();
 
   /// Reads the resource content as a single list of bytes.
   Future<List<int>> readAsBytes();
 
   /// Reads the resource content as a string.
   ///
   /// The content is decoded into a string using an [Encoding].
   /// If no other encoding is provided, it defaults to UTF-8.
   Future<String> readAsString({Encoding encoding});
 }
-
-class _Resource implements Resource {
-  /// Loading strategy for the resource.
-  final ResourceLoader _loader;
-
-  /// The URI of the resource.
-  final _uri;
-
-  const _Resource(uri, {ResourceLoader loader})
-      : _uri = uri, _loader = (loader != null) ? loader : const DefaultLoader();
-  // TODO: Make this `loader ?? const DefaultLoader()` when ?? is const.
-
-  Uri get uri => (_uri is String) ? Uri.parse(_uri) : (_uri as Uri);
-
-  Stream<List<int>> openRead() async* {
-    Uri uri = await _resolvedUri;
-    yield* _loader.openRead(uri);
-  }
-
-  Future<List<int>> readAsBytes() async {
-    Uri uri = await _resolvedUri;
-    return _loader.readAsBytes(uri);
-  }
-
-  Future<String> readAsString({Encoding encoding}) async {
-    Uri uri = await _resolvedUri;
-    return _loader.readAsString(uri, encoding: encoding);
-  }
-
-  Future<Uri> get _resolvedUri => resolveUri(uri);
-}