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dart/frog/leg/scanner/string_scanner.dart

 // 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.
 
 /**
  * Scanner that reads from a String and creates tokens that points to
  * substrings.
  */
 class StringScanner extends ArrayBasedScanner<SourceString> {
   final String string;
@@ skipping 51 matching lines @@
 
   SourceString copyWithoutQuotes(int initial, int terminal) {
     assert(0 <= initial);
     assert(0 <= terminal);
     assert(initial + terminal <= internalString.length);
     return new SubstringWrapper(internalString,
                                 begin + initial, end - terminal);
   }
 
   bool isEmpty() => begin == end;
+
+  bool isPrivate() => !isEmpty() && internalString.charCodeAt(begin) === $_;
 }