adding HtmlEscape to dart:convert

sdk/lib/convert/html_escape.dart

Index: sdk/lib/convert/html_escape.dart
diff --git a/sdk/lib/convert/html_escape.dart b/sdk/lib/convert/html_escape.dart
new file mode 100644
index 0000000000000000000000000000000000000000..9383cfb78b4d46b8463db04f729894c46199c49e
--- /dev/null
+++ b/sdk/lib/convert/html_escape.dart
@@ -0,0 +1,46 @@
+// 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;
+
+const HTML_ESCAPE = const HtmlEscape();
+
+class HtmlEscape extends Converter<String, String> {

[Bob Nystrom, 2013/08/27 18:03:57]

Document all of this.

+
+  const HtmlEscape();
+
+  String convert(String data) => _convert(data);
+
+  StringConversionSink startChunkedConversion(
+    ChunkedConversionSink<String> sink) {
+
+    if (sink is! StringConversionSink) {
+      sink = new StringConversionSink.from(sink);
+    }
+    return new _HtmlEscapeSink(sink);
+  }
+
+  static String _convert(String data) {
+    return data.replaceAll("&", "&amp;")
+        .replaceAll("<", "&lt;")
+        .replaceAll(">", "&gt;")
+        .replaceAll('"', "&quot;")
+        .replaceAll("'", "&apos;")
+        .replaceAll('\u00A0', '&nbsp;');
+  }
+
+}
+
+class _HtmlEscapeSink extends StringConversionSinkBase {
+  final StringConversionSink _sink;
+
+  _HtmlEscapeSink(this._sink);
+
+  void addSlice(String chunk, int start, int end, bool isLast) {
+    _sink.add(HtmlEscape._convert(chunk.substring(start, end)));
+    if (isLast) _sink.close();
+  }
+
+  void close() => _sink.close();
+}