First version of Codecs and Converters.

sdk/lib/convert/json.dart

Index: sdk/lib/convert/json.dart
diff --git a/sdk/lib/convert/json.dart b/sdk/lib/convert/json.dart
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+// 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.
+
+part of dart.convert;
+
+/**
+ * A [JsonEncoder] converts Json-objects to strings.
+ */
+class JsonEncoder extends Converter<Object, String> {
+  JsonEncoder();
+
+  /**
+   * Converts the given Json-object [o] and returns its stringified

[Lasse Reichstein Nielsen, 2013/07/12 11:50:47]

Specify whay "Json-object" is (JSON object).
It's a structure of 
  number, bool, null, string,
  List of JSON objects or
  Maps from String to JSON objects.
It's really a mis-nomer. JSON is a text format, a "JSON object" is just one that
can be directly converted to a JSON string using some heuristic, so what it is
depends on what we allow.

[floitsch, 2013/07/12 16:09:15]

copied the documentation from `stringify`.

+   * Json representation.

[Lasse Reichstein Nielsen, 2013/07/12 11:50:47]

Json -> JSON.
Drop "stringified", JSON is a string.

[floitsch, 2013/07/12 16:09:15]

removed.

+   */
+  String convert(Object o) => OLD_JSON_LIB.stringify(o);
+}
+
+typedef _Reviver(var key, var value);
+
+
+/**
+ * A [JsonDecoder] parses Json strings and builds the corresponding

[Lasse Reichstein Nielsen, 2013/07/12 11:50:47]

JSON strings
JSON objects (if defined above)

[floitsch, 2013/07/12 16:09:15]

Changed to
"JSON strings and builds the corresponding objects."

+ * Json objects.
+ */
+class JsonDecoder extends Converter<String, Object> {
+  final _Reviver _reviver;
+  /**
+   * Constructs a new JsonDecoder.
+   *
+   * The [reviver] may be `null`.
+   */
+  JsonDecoder(reviver(var key, var value)) : this._reviver = reviver;
+
+  /**
+   * Converts the given Json-string [input] to the corresponding object.

[Lasse Reichstein Nielsen, 2013/07/12 11:50:47]

JSON string.

[floitsch, 2013/07/12 16:09:15]

copied the original description.

+   *
+   * If `this` was initialized with a reviver, then the parsing operation
+   * invokes the reviver on every object or list property that has been parsed.
+   */
+  Object convert(String input) => OLD_JSON_LIB.parse(input, _reviver);
+}