String encoding utility methods and tests for Unicode, UTF-8, -16 and -32.

utils/string_encoding/Unicode.dart

Index: utils/string_encoding/Unicode.dart
diff --git a/utils/string_encoding/Unicode.dart b/utils/string_encoding/Unicode.dart
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+// Copyright (c) 2011, 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("Unicode");
+#import("UnicodeCore.dart");
+
+/**
+ * Provide Unicode codepoints for a given string.
+ */
+List<int> stringToCodepoints(String str) {
+  List<int> codepoints;
+  // TODO is16BitCodeUnit() is used to work around a bug with frog/dartc
+  // (http://code.google.com/p/dart/issues/detail?id=1357). Consider
+  // removing after this issue is resolved.
+  if (is16BitCodeUnit()) {
+    codepoints = utf16CodeUnitsToCodepoints(str.charCodes());
+  } else {
+    codepoints = str.charCodes();
+  }
+  return codepoints;
+}
+
+/**
+ * Generate a string for the provided Unicode codepoints.
+ */
+String codepointsToString(List<int> codepoints) {
+  // TODO is16BitCodeUnit() is used to work around a bug with frog/dartc
+  // (http://code.google.com/p/dart/issues/detail?id=1357). Consider
+  // removing after this issue is resolved.
+  if (is16BitCodeUnit()) {
+    return (new String.fromCharCodes(
+        codepointsToUtf16CodeUnits(codepoints)));
+  } else {
+    return (new String.fromCharCodes(codepoints));
+  }
+}