include/wx/meta/pod.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/meta/pod.h
   3 // Purpose:     Test if a type is POD
   4 // Author:      Vaclav Slavik, Jaakko Salli
   5 // Created:     2010-06-14
   6 // RCS-ID:      $Id$
   7 // Copyright:   (c) wxWidgets team
   8 // Licence:     wxWindows licence
   9 /////////////////////////////////////////////////////////////////////////////
  10
  11 #ifndef _WX_META_POD_H_
  12 #define _WX_META_POD_H_
  13
  14 #include "wx/defs.h"
  15
  16 //
  17 // TODO: Use TR1 is_pod<> implementation where available. VC9 SP1 has it
  18 //       in tr1 namespace, VC10 has it in std namespace. GCC 4.2 has it in
  19 //       <tr1/type_traits>, while GCC 4.3 and later have it in <type_traits>.
  20 //
  21
  22 // This macro declares something called "value" inside a class declaration.
  23 //
  24 // It has to be used because VC6 doesn't handle initialization of the static
  25 // variables in the class declaration itself while BCC5.82 doesn't understand
  26 // enums (it compiles the template fine but can't use it later)
  27 #if defined(__VISUALC__) && !wxCHECK_VISUALC_VERSION(7)
  28     #define wxDEFINE_TEMPLATE_BOOL_VALUE(val) enum { value = val }
  29 #else
  30     #define wxDEFINE_TEMPLATE_BOOL_VALUE(val) static const bool value = val
  31 #endif
  32
  33 // Helper to decide if an object of type T is POD (Plain Old Data)
  34 template<typename T>
  35 struct wxIsPod
  36 {
  37     wxDEFINE_TEMPLATE_BOOL_VALUE(false);
  38 };
  39
  40 // Macro to add wxIsPod<T> specialization for given type that marks it
  41 // as Plain Old Data:
  42 #define WX_DECLARE_TYPE_POD(type)                           \
  43     template<> struct wxIsPod<type>                         \
  44     {                                                       \
  45         wxDEFINE_TEMPLATE_BOOL_VALUE(true);                 \
  46     };
  47
  48 WX_DECLARE_TYPE_POD(bool)
  49 WX_DECLARE_TYPE_POD(unsigned char)
  50 WX_DECLARE_TYPE_POD(signed char)
  51 WX_DECLARE_TYPE_POD(unsigned int)
  52 WX_DECLARE_TYPE_POD(signed int)
  53 WX_DECLARE_TYPE_POD(unsigned short int)
  54 WX_DECLARE_TYPE_POD(signed short int)
  55 WX_DECLARE_TYPE_POD(signed long int)
  56 WX_DECLARE_TYPE_POD(unsigned long int)
  57 WX_DECLARE_TYPE_POD(float)
  58 WX_DECLARE_TYPE_POD(double)
  59 WX_DECLARE_TYPE_POD(long double)
  60 #if wxWCHAR_T_IS_REAL_TYPE
  61 WX_DECLARE_TYPE_POD(wchar_t)
  62 #endif
  63 #ifdef wxLongLong_t
  64 WX_DECLARE_TYPE_POD(wxLongLong_t)
  65 WX_DECLARE_TYPE_POD(wxULongLong_t)
  66 #endif
  67
  68 // Visual C++ 6.0 can't compile partial template specializations and as this is
  69 // only an optimization, we can live with pointers not being recognized as
  70 // POD types under VC6
  71 #if !defined(__VISUALC__) || wxCHECK_VISUALC_VERSION(7)
  72
  73 // pointers are Plain Old Data:
  74 template<typename T>
  75 struct wxIsPod<T*>
  76 {
  77     static const bool value = true;
  78 };
  79
  80 template<typename T>
  81 struct wxIsPod<const T*>
  82 {
  83     static const bool value = true;
  84 };
  85
  86 #endif // !VC++ < 7
  87
  88 #endif // _WX_META_POD_H_