Change Hash subclasses to be Converters.

lib/src/hash.dart

Index: lib/src/hash.dart
diff --git a/lib/src/hash.dart b/lib/src/hash.dart
index bb228fa55fed0fc14992eedfa6330b71312f19cd..6f9b33ba0f7fe7d41e5adcad93cb90cdd629fb74 100644
--- a/lib/src/hash.dart
+++ b/lib/src/hash.dart
@@ -4,30 +4,61 @@
 
 library crypto.hash;
 
+import 'dart:convert';
+
+import 'digest.dart';
+import 'digest_sink.dart';
+
 /// An interface for cryptographic hash functions.
 ///
-/// The [add] method adds data to the hash. The [close] method extracts the
-/// message digest.
-///
-/// If multiple instances of a given Hash is needed, the [newInstance] method
-/// can provide a new instance.
-// TODO(floitsch): make Hash implement Sink, EventSink or similar.
-abstract class Hash {
-  /// Add a list of bytes to the hash computation.
+/// Every hash is a converter that takes a list of ints and returns a single
+/// digest. When used in chunked mode, it will only ever add one digest to the
+/// inner [Sink].
+abstract class Hash extends Converter<List<int>, Digest> {
+  /// The internal block size of the hash in bytes.
   ///
-  /// If [this] has already been closed, throws a [StateError].
-  void add(List<int> data);
+  /// This is exposed for use by the [HMAC] class, which needs to know the block
+  /// size for the [Hash] it uses.
+  int get blockSize;
 
-  /// Finish the hash computation and extract the message digest as a list of
-  /// bytes.
-  List<int> close();
+  /// The sink for implementing the deprecated APIs that involved adding data
+  /// directly to the [Hash] instance.
+  ByteConversionSink _sink;
+
+  /// The sink that [_sink] sends the [Digest] to once it finishes hashing.
+  final DigestSink _innerSink = new DigestSink();
+
+  Hash() {
+    _sink = startChunkedConversion(_innerSink);
+  }
+
+  Digest convert(List<int> data) {
+    var innerSink = new DigestSink();
+    var outerSink = startChunkedConversion(innerSink);
+    outerSink.add(data);
+    outerSink.close();
+    return innerSink.value;
+  }
+
+  ByteConversionSink startChunkedConversion(Sink<Digest> sink);
 
   /// Returns a new instance of this hash function.
+  @Deprecated("Expires in 1.0.0. Use Hash.startChunkedConversion() instead.")
   Hash newInstance();
 
-  /// The internal block size of the hash in bytes.
+  /// Add a list of bytes to the hash computation.
   ///
-  /// This is exposed for use by the [HMAC] class, which needs to know the block
-  /// size for the [Hash] it uses.
-  int get blockSize;
+  /// If [this] has already been closed, throws a [StateError].
+  @Deprecated("Expires in 1.0.0. Use Hash.convert() or "
+      "Hash.startChunkedConversion() instead.")
+  void add(List<int> data) => _sink.add(data);
+
+  /// Finish the hash computation and extract the message digest as a list of
+  /// bytes.
+  @Deprecated("Expires in 1.0.0. Use Hash.convert() or "
+      "Hash.startChunkedConversion() instead.")
+  List<int> close() {
+    _sink.close();
+    return _innerSink.value.bytes;
+  }
 }