Add chunked conversion to converters.

tests/lib/convert/chunked_conversion_json_encode1_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 "package:expect/expect.dart";
+import 'dart:convert';
+
+final TESTS = [
+    [ 5, '5' ],
+    [ -42, '-42' ],
+    [ 3.14, '3.14' ],
+    [ true, 'true' ],
+    [ false, 'false' ],
+    [ null, 'null' ],
+    [ 'quote"or\'', '"quote\\"or\'"' ],
+    [ '', '""' ],
+    [ [], "[]" ],
+    [ [3, -4.5, true, "hi", false], '[3,-4.5,true,"hi",false]' ],
+    [ [null], "[null]" ],
+    [ [[null]], "[[null]]" ],
+    [ [[3]], "[[3]]" ],
+    [ {}, "{}" ],
+    [ { "x": 3, "y": 4.5, "z": "hi", "u": true, "v": false },
+      '{"x":3,"y":4.5,"z":"hi","u":true,"v":false}' ],
+    [ { "x": null }, '{"x":null}' ],
+    [ { "x": {} }, '{"x":{}}' ],
+    // Note that -0.0 won't be treated the same in JS. The Json spec seems to
+    // allow it, though.
+    [ { "hi there": 499, "'":-0.0 }, '{"hi there":499,"\'":-0.0}' ],
+    [ r'\foo', r'"\\foo"' ],
+  ];
+
+class MyStringConversionSink extends StringConversionSinkBase {
+  var buffer = new StringBuffer();
+  var callback;
+
+  MyStringConversionSink(this.callback);
+
+  addSlice(str, start, end, bool isLast) {
+    buffer.write(str.substring(start, end));
+    if (isLast) close();
+  }
+
+  close() {
+    callback(buffer.toString());
+  }
+}
+
+String encode(Object o) {
+  var result;
+  var encoder = new JsonEncoder();
+  ChunkedConversionSink stringSink =
+      new MyStringConversionSink((x) => result = x);
+  var objectSink = new JsonEncoder().startChunkedConversion(stringSink);
+  objectSink.add(o);
+  objectSink.close();
+  return result;
+}
+
+String encode2(Object o) {
+  var result;
+  var encoder = new JsonEncoder();
+  ChunkedConversionSink stringSink =
+      new StringConversionSink.withCallback((x) => result = x);
+  var objectSink = encoder.startChunkedConversion(stringSink);
+  objectSink.add(o);
+  objectSink.close();
+  return result;
+}
+
+main() {
+  for (var test in TESTS) {
+    var o = test[0];
+    var expected = test[1];
+    Expect.equals(expected, encode(o));
+    Expect.equals(expected, encode2(o));
+  }
+}