Add a Server interface.

lib/src/io_server.dart

Index: lib/src/io_server.dart
diff --git a/lib/src/io_server.dart b/lib/src/io_server.dart
new file mode 100644
index 0000000000000000000000000000000000000000..854e3417bfaa4594dfc14960b3ee098b4acd5512
--- /dev/null
+++ b/lib/src/io_server.dart
@@ -0,0 +1,60 @@
+// 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.
+
+library shelf.io_server;
+
+import 'dart:async';
+
+import 'dart:io';
+
+import '../shelf_io.dart';
+import 'handler.dart';
+import 'server.dart';
+
+/// A [Server] backed by a `dart:io` [HttpServer].
+class IOServer implements Server {
+  /// The underlying [HttpServer].
+  final HttpServer server;
+
+  /// Whether [mount] has been called.
+  bool _mounted = false;
+
+  Uri get url {
+    if (server.address.isLoopback) {
+      return new Uri(scheme: "http", host: "localhost", port: server.port);
+    }
+
+    // IPv6 addresses in URLs need to be enclosed in square brackets to avoid
+    // URL ambiguity with the ":" in the address.
+    if (server.address.type == InternetAddressType.IP_V6) {
+      return new Uri(
+          scheme: "http",
+          host: "[${server.address.address}]",
+          port: server.port);
+    }
+
+    return new Uri(
+        scheme: "http", host: server.address.address, port: server.port);
+  }
+
+  /// Calls [HttpServer.bind] and wraps the result in an [IOServer].
+  static Future<IOServer> bind(address, int port, {int backlog}) async {
+    backlog ??= 0;
+    var server = await HttpServer.bind(address, port, backlog: backlog);
+    return new IOServer(server);
+  }
+
+  IOServer(this.server);
+
+  void mount(Handler handler) {
+    if (_mounted) {
+      throw new StateError("Can't mount two handlers for the same server.");
+    }
+    _mounted = true;
+
+    serveRequests(server, handler);
+  }
+
+  Future close() => server.close();
+}