boost/type_traits/is_default_constructible.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).
//
// See http://www.boost.org/libs/type_traits for most recent version including documentation.
#ifndef BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED
#define BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED
#include <cstddef> // size_t
#include <boost/type_traits/integral_constant.hpp>
#include <boost/detail/workaround.hpp>
#include <boost/type_traits/is_complete.hpp>
#include <boost/static_assert.hpp>
#if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
#include <boost/type_traits/is_abstract.hpp>
#endif
#if defined(__clang__) || (defined(__GNUC__) && (__GNUC__ <= 5)) || (defined(BOOST_MSVC) && (BOOST_MSVC == 1800))
#include <utility> // std::pair
#endif
#if !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1800) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40500)
#include <boost/type_traits/detail/yes_no_type.hpp>
namespace boost{
namespace detail{
struct is_default_constructible_imp
{
template<typename _Tp, typename = decltype(_Tp())>
static boost::type_traits::yes_type test(int);
template<typename>
static boost::type_traits::no_type test(...);
};
#if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
template<class T, bool b>
struct is_default_constructible_abstract_filter
{
static const bool value = sizeof(is_default_constructible_imp::test<T>(0)) == sizeof(boost::type_traits::yes_type);
};
template<class T>
struct is_default_constructible_abstract_filter<T, true>
{
static const bool value = false;
};
#endif
}
#if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
template <class T> struct is_default_constructible : public integral_constant<bool, detail::is_default_constructible_abstract_filter<T, boost::is_abstract<T>::value>::value>
{
BOOST_STATIC_ASSERT_MSG(boost::is_complete<T>::value, "Arguments to is_default_constructible must be complete types");
};
#else
template <class T> struct is_default_constructible : public integral_constant<bool, sizeof(boost::detail::is_default_constructible_imp::test<T>(0)) == sizeof(boost::type_traits::yes_type)>
{
BOOST_STATIC_ASSERT_MSG(boost::is_complete<T>::value, "Arguments to is_default_constructible must be complete types");
};
#endif
template <class T, std::size_t N> struct is_default_constructible<T[N]> : public is_default_constructible<T>{};
template <class T> struct is_default_constructible<T[]> : public is_default_constructible<T>{};
template <class T> struct is_default_constructible<T&> : public integral_constant<bool, false>{};
#if defined(__clang__) || (defined(__GNUC__) && (__GNUC__ <= 5))|| (defined(BOOST_MSVC) && (BOOST_MSVC == 1800))
template <class T, class U> struct is_default_constructible<std::pair<T,U> > : public integral_constant<bool, is_default_constructible<T>::value && is_default_constructible<U>::value>{};
#endif
#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
template <class T> struct is_default_constructible<T&&> : public integral_constant<bool, false>{};
#endif
template <> struct is_default_constructible<void> : public integral_constant<bool, false>{};
template <> struct is_default_constructible<void const> : public integral_constant<bool, false>{};
template <> struct is_default_constructible<void volatile> : public integral_constant<bool, false>{};
template <> struct is_default_constructible<void const volatile> : public integral_constant<bool, false>{};
#else
#include <boost/type_traits/is_pod.hpp>
namespace boost{
// We don't know how to implement this, note we can not use has_trivial_constructor here
// because the correct implementation of that trait requires this one:
template <class T> struct is_default_constructible : public is_pod<T>{};
template <> struct is_default_constructible<void> : public integral_constant<bool, false>{};
template <> struct is_default_constructible<void const> : public integral_constant<bool, false>{};
template <> struct is_default_constructible<void volatile> : public integral_constant<bool, false>{};
template <> struct is_default_constructible<void const volatile> : public integral_constant<bool, false>{};
#endif
} // namespace boost
#endif // BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED