Switch from interfaces to abstract classes in dart:io.

runtime/bin/input_stream.dart

Index: runtime/bin/input_stream.dart
diff --git a/runtime/bin/input_stream.dart b/runtime/bin/input_stream.dart
index 38e8f1d81e3d0fa473d07af41863ca2682790c8e..29f182841ee2c66676f6d847e4e46c383009ee4e 100644
--- a/runtime/bin/input_stream.dart
+++ b/runtime/bin/input_stream.dart
@@ -31,7 +31,7 @@
  * Always set up appropriate handlers when using input streams.
  *
  */
-interface InputStream {
+abstract class InputStream {
   /**
    * Reads data from the stream. Returns a system allocated buffer
    * with up to [len] bytes. If no value is passed for [len] all
@@ -114,12 +114,15 @@ class Encoding {
  * string data. This data can be read either as string chunks or as
  * lines separated by line termination character sequences.
  */
-interface StringInputStream default _StringInputStream {
+abstract class StringInputStream {
   /**
    * Decodes a binary input stream into characters using the specified
    * encoding. The default encoding is UTF-8 - `Encoding.UTF_8`.

[Søren Gjesse, 2012/09/18 09:34:16]

No need for documentation of the default value.

[Mads Ager (google), 2012/09/18 10:46:39]

Done.

    */
-  StringInputStream(InputStream input, [Encoding encoding]);
+  factory StringInputStream(InputStream input,
+                            [Encoding encoding = Encoding.UTF_8]) {
+    return new _StringInputStream(input, encoding);
+  }
 
   /**
    * Reads as many characters as is available from the stream. If no data is
@@ -187,12 +190,14 @@ interface StringInputStream default _StringInputStream {
  * A chunked input stream wraps a basic input stream and supplies
  * binary data in configurable chunk sizes.
  */
-interface ChunkedInputStream default _ChunkedInputStream {
+abstract class ChunkedInputStream {
   /**
    * Adds buffering to an input stream and provide the ability to read
    * the data in known size chunks.
    */
-  ChunkedInputStream(InputStream input, [int chunkSize]);
+  factory ChunkedInputStream(InputStream input, [int chunkSize = 0]) {
+    return new _ChunkedInputStream(input, chunkSize);
+  }
 
   /**
    * Reads [chunkSize] bytes from the stream. If [chunkSize] bytes are