Revert "Revert "Make stdout/stderr async""

sdk/lib/io/console.dart

Index: sdk/lib/io/console.dart
diff --git a/sdk/lib/io/console.dart b/sdk/lib/io/console.dart
new file mode 100644
index 0000000000000000000000000000000000000000..c4ab7f27f0df3a043fb243c94da6f30f1ac1494e
--- /dev/null
+++ b/sdk/lib/io/console.dart
@@ -0,0 +1,97 @@
+// Copyright (c) 2013, 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.
+
+part of dart.io;
+
+Console _console;
+
+Console get console {
+  if (_console == null) {
+    _console = new Console._();
+  }
+  return _console;
+}
+
+/**
+ * [Console] provides synchronous write access to stdout and stderr.
+ *
+ * The direct access to stdout and stderr through [stdout] and [stderr]
+ * provides non-blocking async operations.
+ */
+class Console {
+  final ConsoleSink _stdout;
+  final ConsoleSink _stderr;
+
+  Console._()
+      : _stdout = new ConsoleSink._(1),
+        _stderr = new ConsoleSink._(2);
+
+  /**
+   * Write to stdout.
+   */
+  ConsoleSink get log => _stdout;
+
+  /**
+   * Write to stderr.
+   */
+  ConsoleSink get error => _stderr;
+}
+
+/**
+ * Sink class used for console writing.
+ *
+ * This class has a call method so you can call it directly. Calling
+ * it directly is the same as calling its `writeln` method.
+ */
+class ConsoleSink implements Sink<List<int>>, StringSink {
+  IOSink _sink;
+
+  ConsoleSink._(int fd) {
+    _sink = new IOSink(new _ConsoleConsumer(fd));
+  }
+
+  void call([Object message = ""]) => _sink.writeln(message);
+
+  void add(List<int> data) => _sink.add(data);
+
+  void close() {}
+
+  void write(Object obj) => _sink.write(obj);
+
+  void writeAll(Iterable objects, [String separator=""]) =>
+      _sink.writeAll(objects, separator);
+
+  void writeCharCode(int charCode) => _sink.writeCharCode(charCode);
+
+  void writeln([Object obj=""]) => _sink.writeln(obj);
+}
+
+class _ConsoleConsumer implements StreamConsumer<List<int>> {
+  final _file;
+
+  _ConsoleConsumer(int fd) : _file = _File._openStdioSync(fd);
+
+  Future addStream(Stream<List<int>> stream) {
+    var completer = new Completer();
+    var sub;
+    sub = stream.listen(
+        (data) {
+          try {
+            _file.writeFromSync(data);
+          } catch (e, s) {
+            sub.cancel();
+            completer.completeError(e, s);
+          }
+        },
+        onError: completer.completeError,
+        onDone: completer.complete,
+        cancelOnError: true);
+    return completer.future;
+  }
+
+  Future close() {
+    _file.closeSync();
+    return new Future.value();
+  }
+}