boost/type_traits/integral_constant.hpp
// (C) Copyright John Maddock 2015.
// Use, modification and distribution are subject to the
// Boost Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_TYPE_TRAITS_INTEGRAL_CONSTANT_HPP
#define BOOST_TYPE_TRAITS_INTEGRAL_CONSTANT_HPP
#include <boost/config.hpp>
#include <boost/detail/workaround.hpp>
#if (BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1400)) \
|| BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x610)) \
|| BOOST_WORKAROUND(__DMC__, BOOST_TESTED_AT(0x840)) \
|| BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3202)) \
|| BOOST_WORKAROUND(BOOST_INTEL_CXX_VERSION, BOOST_TESTED_AT(810)) )\
|| defined(BOOST_MPL_CFG_NO_ADL_BARRIER_NAMESPACE)
namespace boost{
namespace mpl
{
template <bool B> struct bool_;
template <class I, I val> struct integral_c;
struct integral_c_tag;
}
}
#else
namespace mpl_{
template <bool B> struct bool_;
template <class I, I val> struct integral_c;
struct integral_c_tag;
}
namespace boost
{
namespace mpl
{
using ::mpl_::bool_;
using ::mpl_::integral_c;
using ::mpl_::integral_c_tag;
}
}
#endif
namespace boost{
template <class T, T val>
struct integral_constant
{
typedef mpl::integral_c_tag tag;
typedef T value_type;
typedef integral_constant<T, val> type;
static const T value = val;
operator const mpl::integral_c<T, val>& ()const
{
static const char data[sizeof(long)] = { 0 };
static const void* pdata = data;
return *(reinterpret_cast<const mpl::integral_c<T, val>*>(pdata));
}
BOOST_CONSTEXPR operator T()const { return val; }
};
template <class T, T val>
T const integral_constant<T, val>::value;
template <bool val>
struct integral_constant<bool, val>
{
typedef mpl::integral_c_tag tag;
typedef bool value_type;
typedef integral_constant<bool, val> type;
static const bool value = val;
operator const mpl::bool_<val>& ()const
{
static const char data[sizeof(long)] = { 0 };
static const void* pdata = data;
return *(reinterpret_cast<const mpl::bool_<val>*>(pdata));
}
BOOST_CONSTEXPR operator bool()const { return val; }
};
template <bool val>
bool const integral_constant<bool, val>::value;
typedef integral_constant<bool, true> true_type;
typedef integral_constant<bool, false> false_type;
}
#endif