Make convert library strong-mode compliant.

sdk/lib/convert/chunked_conversion.dart

Index: sdk/lib/convert/chunked_conversion.dart
diff --git a/sdk/lib/convert/chunked_conversion.dart b/sdk/lib/convert/chunked_conversion.dart
index 4c962eb62c589db90f57512002408d7f12e931be..5fdc6aad8eba0a1921578a25c644990f63cf4bde 100644
--- a/sdk/lib/convert/chunked_conversion.dart
+++ b/sdk/lib/convert/chunked_conversion.dart
@@ -7,6 +7,39 @@ part of dart.convert;
 typedef void _ChunkedConversionCallback<T>(T accumulated);
 
 /**
+ * A converter that supports chunked conversions.
+ */
+// This class may be used as Mixin.
+abstract class ChunkedConverter<S, T, S2, T2> extends Converter<S, T>
+    implements StreamTransformer<S2, T2> {
+
+  const ChunkedConverter();
+
+  /**
+   * Starts a chunked conversion.
+   */
+  ChunkedConversionSink<S2> startChunkedConversion(Sink<T2> sink) {
+    throw new UnsupportedError(
+        "This converter does not support chunked conversions: $this");
+  }
+
+  Stream<T2> bind(Stream<S2> stream) {
+    return new Stream<T2>.eventTransformed(
+        stream,
+        (EventSink<T2> sink) =>
+            new _ConverterStreamEventSink<S2, T2>(this, sink));
+  }
+
+  Converter<S, dynamic> fuse(Converter<T, dynamic> other) {
+    if (other is ChunkedConverter<T, dynamic, T2, dynamic>) {
+      return new _FusedChunkedConverter<S, T, dynamic, S2, T2, dynamic>(
+          this, other);
+    }
+    return super.fuse(other);
+  }
+}
+
+/**
  * A [ChunkedConversionSink] is used to transmit data more efficiently between
  * two converters during chunked conversions.
  *
@@ -55,7 +88,7 @@ class _SimpleCallbackSink<T> extends ChunkedConversionSink<T> {
 }
 
 /**
- * This class converts implements the logic for a chunked conversion as a
+ * This class implements the logic for a chunked conversion as a
  * stream transformer.
  *
  * It is used as strategy in the [EventTransformStream].
@@ -71,9 +104,10 @@ class _ConverterStreamEventSink<S, T> implements EventSink<S> {
    * The input sink for new data. All data that is received with
    * [handleData] is added into this sink.
    */
-  ChunkedConversionSink _chunkedSink;
+  ChunkedConversionSink<S> _chunkedSink;
 
-  _ConverterStreamEventSink(Converter converter, EventSink<T> sink)
+  _ConverterStreamEventSink(
+      ChunkedConverter<dynamic, dynamic, S, T> converter, EventSink<T> sink)
       : this._eventSink = sink,
         _chunkedSink = converter.startChunkedConversion(sink);
 
@@ -83,3 +117,22 @@ class _ConverterStreamEventSink<S, T> implements EventSink<S> {
   }
   void close() => _chunkedSink.close();
 }
+
+/**
+ * Fuses two chunked converters.
+ *
+ * For a non-chunked conversion converts the input in sequence.
+ */
+class _FusedChunkedConverter<S, M, T, S2, M2, T2> extends
+    ChunkedConverter<S, T, S2, T2> {
+  final ChunkedConverter<S, M, S2, M2> _first;
+  final ChunkedConverter<M, T, M2, T2> _second;
+
+  _FusedChunkedConverter(this._first, this._second);
+
+  T convert(S input) => _second.convert(_first.convert(input));
+
+  ChunkedConversionSink<S2> startChunkedConversion(Sink<T2> sink) {
+    return _first.startChunkedConversion(_second.startChunkedConversion(sink));
+  }
+}