TypeInfo.h 

  1 ////////////////////////////////////////////////////////////////////////////////
  2 // The Loki Library
  3 // Copyright (c) 2001 by Andrei Alexandrescu
  4 // This code accompanies the book:
  5 // Alexandrescu, Andrei. "Modern C++ Design: Generic Programming and Design 
  6 //     Patterns Applied". Copyright (c) 2001. Addison-Wesley.
  7 // Permission to use, copy, modify, distribute and sell this software for any 
  8 //     purpose is hereby granted without fee, provided that the above copyright 
  9 //     notice appear in all copies and that both that copyright notice and this 
 10 //     permission notice appear in supporting documentation.
 11 // The author or Addison-Welsey Longman make no representations about the 
 12 //     suitability of this software for any purpose. It is provided "as is" 
 13 //     without express or implied warranty.
 14 ////////////////////////////////////////////////////////////////////////////////
 15 
 16 // Last update: June 20, 2001
 17 
 18 #ifndef TYPEINFO_INC_
 19 #define TYPEINFO_INC_
 20 
 21 #include <typeinfo>
 22 #include <cassert>
 23 #include "Typelist.h"
 24 
 25 namespace Loki
 26 {
 27 ////////////////////////////////////////////////////////////////////////////////
 28 // class TypeInfo
 29 // Purpose: offer a first-class, comparable wrapper over std::type_info
 30 ////////////////////////////////////////////////////////////////////////////////
 31 
 32     class TypeInfo
 33     {
 34     public:
 35         // Constructors
 36         TypeInfo(); // needed for containers
 37         TypeInfo(const std::type_info&); // non-explicit
 38 
 39         // Access for the wrapped std::type_info
 40         const std::type_info& Get() const;
 41         // Compatibility functions
 42         bool before(const TypeInfo& rhs) const;
 43         const char* name() const;
 44 
 45     private:
 46         const std::type_info* pInfo_;
 47     };
 48     
 49 // Implementation
 50     
 51     inline TypeInfo::TypeInfo()
 52     {
 53         class Nil {};
 54         pInfo_ = &typeid(Nil);
 55         assert(pInfo_);
 56     }
 57     
 58     inline TypeInfo::TypeInfo(const std::type_info& ti)
 59     : pInfo_(&ti)
 60     { assert(pInfo_); }
 61     
 62     inline bool TypeInfo::before(const TypeInfo& rhs) const
 63     {
 64         assert(pInfo_);
 65         return pInfo_->before(*rhs.pInfo_);
 66     }
 67 
 68     inline const std::type_info& TypeInfo::Get() const
 69     {
 70         assert(pInfo_);
 71         return *pInfo_;
 72     }
 73     
 74     inline const char* TypeInfo::name() const
 75     {
 76         assert(pInfo_);
 77         return pInfo_->name();
 78     }
 79 
 80 // Comparison operators
 81     
 82     inline bool operator==(const TypeInfo& lhs, const TypeInfo& rhs)
 83     { return lhs.Get() == rhs.Get(); }
 84 
 85     inline bool operator<(const TypeInfo& lhs, const TypeInfo& rhs)
 86     { return lhs.before(rhs); }
 87 
 88     inline bool operator!=(const TypeInfo& lhs, const TypeInfo& rhs)
 89     { return !(lhs == rhs); }    
 90     
 91     inline bool operator>(const TypeInfo& lhs, const TypeInfo& rhs)
 92     { return rhs < lhs; }
 93     
 94     inline bool operator<=(const TypeInfo& lhs, const TypeInfo& rhs)
 95     { return !(lhs > rhs); }
 96      
 97     inline bool operator>=(const TypeInfo& lhs, const TypeInfo& rhs)
 98     { return !(lhs < rhs); }
 99 }
100 
101 ////////////////////////////////////////////////////////////////////////////////
102 // Change log:
103 // June 20, 2001: ported by Nick Thurn to gcc 2.95.3. Kudos, Nick!!!
104 ////////////////////////////////////////////////////////////////////////////////
105 
106 #endif // TYPEINFO_INC_
posted @ 2012-10-31 15:25  crazylhf  阅读(459)  评论(0)    收藏  举报