Make the package strong-mode clean.

lib/src/hex/decoder.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 convert.hex.decoder;
 
 import 'dart:convert';
 import 'dart:typed_data';
 
 import '../utils.dart';
 
 /// The canonical instance of [HexDecoder].
 const hexDecoder = const HexDecoder._();
 
 /// A converter that decodes hexadecimal strings into byte arrays.
 ///
 /// Because two hexadecimal digits correspond to a single byte, this will throw
 /// a [FormatException] if given an odd-length string. It will also throw a
 /// [FormatException] if given a string containing non-hexadecimal code units.
-class HexDecoder extends Converter<String, List<int>> {
+class HexDecoder
+    extends ChunkedConverter<String, List<int>, String, List<int>> {
   const HexDecoder._();
 
   List<int> convert(String string) {
     if (!string.length.isEven) {
       throw new FormatException("Invalid input length, must be even.",
           string, string.length);
     }
 
     var bytes = new Uint8List(string.length ~/ 2);
     _decode(string.codeUnits, 0, string.length, bytes, 0);
@@ skipping 20 matching lines @@
 
   void addSlice(String string, int start, int end, bool isLast) {
     RangeError.checkValidRange(start, end, string.length);
 
     if (start == end) {
       if (isLast) _close(string, end);
       return;
     }
 
     var codeUnits = string.codeUnits;
-    var bytes;
-    var bytesStart;
+    Uint8List bytes;
+    int bytesStart;
     if (_lastDigit == null) {
       bytes = new Uint8List((end - start) ~/ 2);
       bytesStart = 0;
     } else {
       var hexPairs = (end - start - 1) ~/ 2;
       bytes = new Uint8List(1 + hexPairs);
       bytes[0] = _lastDigit + digitForCodeUnit(codeUnits, start);
       start++;
       bytesStart = 1;
     }
@@ skipping 38 matching lines @@
   void add(List<int> chunk) => addSlice(chunk, 0, chunk.length, false);
 
   void addSlice(List<int> chunk, int start, int end, bool isLast) {
     RangeError.checkValidRange(start, end, chunk.length);
 
     if (start == end) {
       if (isLast) _close(chunk, end);
       return;
     }
 
-    var bytes;
-    var bytesStart;
+    Uint8List bytes;
+    int bytesStart;
     if (_lastDigit == null) {
       bytes = new Uint8List((end - start) ~/ 2);
       bytesStart = 0;
     } else {
       var hexPairs = (end - start - 1) ~/ 2;
       bytes = new Uint8List(1 + hexPairs);
       bytes[0] = _lastDigit + digitForCodeUnit(chunk, start);
       start++;
       bytesStart = 1;
     }
@@ skipping 30 matching lines @@
   var destinationIndex = destinationStart;
   for (var i = sourceStart; i < sourceEnd - 1; i += 2) {
     var firstDigit = digitForCodeUnit(codeUnits, i);
     var secondDigit = digitForCodeUnit(codeUnits, i + 1);
     destination[destinationIndex++] = 16 * firstDigit + secondDigit;
   }
 
   if ((sourceEnd - sourceStart).isEven) return null;
   return 16 * digitForCodeUnit(codeUnits, sourceEnd - 1);
 }