Switch from interfaces to abstract classes in dart:io.

runtime/bin/string_stream.dart

 // Copyright (c) 2012, 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.
 
 // Interface for decoders decoding binary data into string data. The
 // decoder keeps track of line breaks during decoding.
-interface _StringDecoder {
+abstract class _StringDecoder {
   // Add more binary data to be decoded. The ownership of the buffer
   // is transfered to the decoder and the caller most not modify it any more.
   int write(List<int> buffer);
 
   // Returns whether any decoded data is available.
   bool isEmpty();
 
   // Returns the number of available decoded characters.
   int available();
 
@@ skipping 220 matching lines @@
     while (_bufferList.length > 0) {
       int byte = _bufferList.next();
       addChar(byte);
     }
     return true;
   }
 }
 
 
 // Interface for encoders encoding string data into binary data.
-interface _StringEncoder {
+abstract class _StringEncoder {
   List<int> encodeString(String string);
 }
 
 
 // Utility class for encoding a string into UTF-8 byte stream.
 class _UTF8Encoder implements _StringEncoder {
   List<int> encodeString(String string) {
     int size = _encodingSize(string);
     List<int> result = new Uint8List(size);
     _encodeString(string, result);
@@ skipping 89 matching lines @@
 
 
 class EncoderException implements Exception {
   const EncoderException([String this.message]);
   String toString() => "EncoderException: $message";
   final String message;
 }
 
 
 class _StringInputStream implements StringInputStream {
-  _StringInputStream(InputStream this._input,
-                     [Encoding encoding = Encoding.UTF_8])
-      : _encoding = encoding {
+  _StringInputStream(InputStream this._input, Encoding this._encoding) {
     _decoder = _StringDecoders.decoder(encoding);
     _input.onData = _onData;
     _input.onClosed = _onClosed;
   }
 
   String read([int len]) {
     String result = _decoder.decoded(len);
     _checkInstallDataHandler();
     return result;
   }
@@ skipping 154 matching lines @@
   bool _inputClosed = false;  // Is the underlying input stream closed?
   bool _closed = false;  // Is this stream closed.
   bool _eof = false;  // Has all data been read from the decoder?
   Timer _scheduledDataCallback;
   Timer _scheduledLineCallback;
   Timer _scheduledCloseCallback;
   Function _clientDataHandler;
   Function _clientLineHandler;
   Function _clientCloseHandler;
 }