base/strings/nullable_string16.h

   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_