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      1 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef BASE_STRINGS_NULLABLE_STRING16_H_
      6 #define BASE_STRINGS_NULLABLE_STRING16_H_
      7 
      8 #include <iosfwd>
      9 
     10 #include "base/base_export.h"
     11 #include "base/strings/string16.h"
     12 
     13 namespace base {
     14 
     15 // This class is a simple wrapper for string16 which also contains a null
     16 // state.  This should be used only where the difference between null and
     17 // empty is meaningful.
     18 class NullableString16 {
     19  public:
     20   NullableString16() : is_null_(true) { }
     21   NullableString16(const string16& string, bool is_null)
     22       : string_(string), is_null_(is_null) {
     23   }
     24 
     25   const string16& string() const { return string_; }
     26   bool is_null() const { return is_null_; }
     27 
     28  private:
     29   string16 string_;
     30   bool is_null_;
     31 };
     32 
     33 inline bool operator==(const NullableString16& a, const NullableString16& b) {
     34   return a.is_null() == b.is_null() && a.string() == b.string();
     35 }
     36 
     37 inline bool operator!=(const NullableString16& a, const NullableString16& b) {
     38   return !(a == b);
     39 }
     40 
     41 BASE_EXPORT std::ostream& operator<<(std::ostream& out,
     42                                      const NullableString16& value);
     43 
     44 }  // namespace base
     45 
     46 #endif  // BASE_STRINGS_NULLABLE_STRING16_H_
     47