ceph/src/boost/boost/type_traits/integral_constant.hpp

   1 //  (C) Copyright John Maddock 2015.
   2 //  Use, modification and distribution are subject to the
   3 //  Boost Software License, Version 1.0. (See accompanying file
   4 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   5
   6 #ifndef BOOST_TYPE_TRAITS_INTEGRAL_CONSTANT_HPP
   7 #define BOOST_TYPE_TRAITS_INTEGRAL_CONSTANT_HPP
   8
   9 #include <boost/config.hpp>
  10 #include <boost/detail/workaround.hpp>
  11
  12 #if (BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1400)) \
  13    || BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x610)) \
  14    || BOOST_WORKAROUND(__DMC__, BOOST_TESTED_AT(0x840)) \
  15    || BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3202)) \
  16    || BOOST_WORKAROUND(BOOST_INTEL_CXX_VERSION, BOOST_TESTED_AT(810)) )\
  17    || defined(BOOST_MPL_CFG_NO_ADL_BARRIER_NAMESPACE)
  18
  19
  20 namespace boost{
  21    namespace mpl
  22    {
  23       template <bool B> struct bool_;
  24       template <class I, I val> struct integral_c;
  25       struct integral_c_tag;
  26    }
  27 }
  28
  29 #else
  30
  31 namespace mpl_{
  32
  33    template <bool B> struct bool_;
  34    template <class I, I val> struct integral_c;
  35    struct integral_c_tag;
  36 }
  37
  38 namespace boost
  39 {
  40    namespace mpl
  41    {
  42       using ::mpl_::bool_;
  43       using ::mpl_::integral_c;
  44       using ::mpl_::integral_c_tag;
  45    }
  46 }
  47
  48 #endif
  49
  50 namespace boost{
  51
  52    template <class T, T val>
  53    struct integral_constant
  54    {
  55       typedef mpl::integral_c_tag tag;
  56       typedef T value_type;
  57       typedef integral_constant<T, val> type;
  58       static const T value = val;
  59       //
  60       // This helper function is just to disable type-punning
  61       // warnings from GCC:
  62       //
  63       template <class U>
  64       static U& dereference(U* p) { return *p; }
  65
  66       operator const mpl::integral_c<T, val>& ()const
  67       {
  68          static const char data[sizeof(long)] = { 0 };
  69          return dereference(reinterpret_cast<const mpl::integral_c<T, val>*>(&data));
  70       }
  71       BOOST_CONSTEXPR operator T()const { return val; }
  72    };
  73
  74    template <class T, T val>
  75    T const integral_constant<T, val>::value;
  76
  77    template <bool val>
  78    struct integral_constant<bool, val>
  79    {
  80       typedef mpl::integral_c_tag tag;
  81       typedef bool value_type;
  82       typedef integral_constant<bool, val> type;
  83       static const bool value = val;
  84       //
  85       // This helper function is just to disable type-punning
  86       // warnings from GCC:
  87       //
  88       template <class T>
  89       static T& dereference(T* p) { return *p; }
  90
  91       operator const mpl::bool_<val>& ()const
  92       {
  93          static const char data = 0;
  94          return dereference(reinterpret_cast<const mpl::bool_<val>*>(&data));
  95       }
  96       BOOST_CONSTEXPR operator bool()const { return val; }
  97    };
  98
  99    template <bool val>
 100    bool const integral_constant<bool, val>::value;
 101
 102    typedef integral_constant<bool, true> true_type;
 103    typedef integral_constant<bool, false> false_type;
 104
 105 }
 106
 107 #endif