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