Improve the style of code in lib/.

lib/src/base64/encoder_sink.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.
+
+library crypto.base64.encoder_sink;
+
+import 'dart:convert';
+
+import 'encoder.dart';
+
+/// A [ChunkedConversionSink] for encoding chunks of data to Base64.
+class Base64EncoderSink extends ChunkedConversionSink<List<int>> {
+  /// The encoder used to encode each chunk.
+  final Base64Encoder _encoder;
+
+  /// The underlying sink to which to emit the encoded strings.
+  final ChunkedConversionSink<String> _outSink;
+
+  /// The buffer of as-yet-unconverted bytes.
+  ///
+  /// This is used to ensure that we don't generate interstitial padding
+  /// characters.
+  final _buffer = new List<int>();
+
+  /// The length of [_buffer]; that is, the number of unconverted bytes.
+  var _bufferCount = 0;
+
+  Base64EncoderSink(this._outSink, urlSafe, addLineSeparator)
+      : _encoder = new Base64Encoder(
+            urlSafe: urlSafe, addLineSeparator: addLineSeparator);
+
+  void add(List<int> chunk) {
+    var nextBufferCount = (chunk.length + _bufferCount) % 3;
+    var decodableLength = _bufferCount + chunk.length - nextBufferCount;
+
+    if (_bufferCount + chunk.length > _buffer.length) {
+      _buffer.replaceRange(_bufferCount, _buffer.length,
+          chunk.sublist(0, _buffer.length - _bufferCount));
+      _buffer.addAll(chunk.sublist(_buffer.length - _bufferCount));
+    } else {
+      _buffer.replaceRange(_bufferCount, _bufferCount + chunk.length, chunk);
+    }
+
+    _outSink.add(_encoder.convert(_buffer, 0, decodableLength));
+    _buffer.removeRange(0, decodableLength);
+    _bufferCount = nextBufferCount;
+  }
+
+  void close() {
+    if (_bufferCount > 0) {
+      _outSink.add(_encoder.convert(_buffer.sublist(0, _bufferCount)));
+    }
+    _outSink.close();
+  }
+}
+