First version of Codecs and Converters.

tests/lib/codec/codec1_test.dart

+// Copyright (c) 2013, 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.
+
+import 'dart:codec';
+import 'dart:convert';
+
+import 'package:expect/expect.dart';
+
+class MyCodec extends Codec<int, String> {
+  const MyCodec();
+
+  Converter<int, String> get encoder => new IntStringConverter();
+  Converter<String, int> get decoder => new StringIntConverter();
+}
+
+class IntStringConverter extends Converter<int, String> {
+  String convert(int i) => i.toString();
+}
+
+class StringIntConverter extends Converter<String, int> {
+  int convert(String str) => int.parse(str);
+}
+
+class MyCodec2 extends Codec<int, String> {
+  const MyCodec2();
+
+  Converter<int, String> get encoder => new IntStringConverter2();
+  Converter<String, int> get decoder => new StringIntConverter2();
+}
+
+class IntStringConverter2 extends Converter<int, String> {
+  String convert(int i) => (i + 99).toString();
+}
+
+class StringIntConverter2 extends Converter<String, int> {
+  int convert(String str) => int.parse(str) + 400;
+}
+
+const TEST_CODEC = const MyCodec();
+const TEST_CODEC2 = const MyCodec2();
+
+main() {
+  Expect.equals("0", TEST_CODEC.encode(0));
+  Expect.equals(5, TEST_CODEC.decode("5"));
+  Expect.equals(3, TEST_CODEC.decode(TEST_CODEC.encode(3)));
+
+  Expect.equals("99", TEST_CODEC2.encode(0));
+  Expect.equals(405, TEST_CODEC2.decode("5"));
+  Expect.equals(499, TEST_CODEC2.decode(TEST_CODEC2.encode(0)));
+
+  var inverted, fused;
+  inverted = TEST_CODEC.inverted;
+  fused = TEST_CODEC.fuse(inverted);
+  Expect.equals(499, fused.encode(499));
+  Expect.equals(499, fused.decode(499));
+
+  fused = inverted.fuse(TEST_CODEC);
+  Expect.equals("499", fused.encode("499"));
+  Expect.equals("499", fused.decode("499"));
+
+  inverted = TEST_CODEC2.inverted;
+  fused = TEST_CODEC2.fuse(inverted);
+  Expect.equals(499, fused.encode(0));
+  Expect.equals(499, fused.decode(0));
+
+  fused = TEST_CODEC.fuse(inverted);
+  Expect.equals(405, fused.encode(5));
+  Expect.equals(101, fused.decode(2));
+}