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Add is_constructible implementation, compatible with several C++03 compilers

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Ion Gaztañaga
2025-11-29 21:48:11 +01:00
parent 86a69d852e
commit 5039410be5
2 changed files with 243 additions and 0 deletions
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180
include/boost/container/detail/is_constructible.hpp Normal file
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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2005-2015. Distributed under 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/container for documentation.
//
//////////////////////////////////////////////////////////////////////////////
#ifndef BOOST_CONTAINER_DETAIL_IS_CONSTRUCTIBLE_HPP
#define BOOST_CONTAINER_DETAIL_IS_CONSTRUCTIBLE_HPP
#ifndef BOOST_CONFIG_HPP
# include <boost/config.hpp>
#endif
#if defined(BOOST_HAS_PRAGMA_ONCE)
# pragma once
#endif
#include <boost/interprocess/detail/config_begin.hpp>
#include <boost/interprocess/detail/workaround.hpp>
#include <cstddef> // for size_t
#include <boost/move/utility_core.hpp> //declval
namespace boost_container_is_constructible {
typedef char yes_type;
struct no_type { char padding[8]; };
template<bool Cond, typename T = void> struct enable_if {};
template<typename T> struct enable_if<true, T> { typedef T type; };
template<typename E, typename T> struct t_enable { typedef T type; };
} //namespace boost_container_is_constructible {
#if !defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) && !defined(BOOST_NO_CXX11_DECLTYPE)
namespace boost {
namespace container {
template <typename T, typename ...Args>
struct is_constructible\
{
private:
typedef char yes_type;
struct no_type { char padding[8]; };
template <typename U>
static decltype( new U(boost::move_detail::declval<Args>()...), yes_type() ) test(int);
template <typename U>
static no_type test(...);
public:
static const bool value = sizeof(test<T>(0)) == sizeof(yes_type);
};
} //namespace container {
} //namespace boost {
#else //Use macro expansion
#include <boost/move/detail/fwd_macros.hpp>
#if defined(BOOST_NO_CXX11_DECLTYPE)
namespace boost_container_is_constructible {
// Example for N == 2
//
//template <typename T, typename P0, typename P1>
//struct is_constructible2
//{
// private:
// template<typename U>
// static char test( typename enable_if< (sizeof( new U(boost::move_detail::declval<P0>(), boost::move_detail::declval<P1>()))!= 0), int>::type );
//
// template <typename U>
// static no_type test(...);
//
// public:
// static const bool value = sizeof(test<T>(0)) == sizeof(yes_type);
//};
#define BOOST_INTRUSIVE_IS_CONSTRUCTIBLE_IMPL(N) \
template <typename T BOOST_MOVE_I##N BOOST_MOVE_CLASS##N>\
struct BOOST_MOVE_CAT(is_constructible_impl, N)\
{\
private:\
template <typename U>\
static yes_type test( typename enable_if< (sizeof( new U(BOOST_MOVE_DECLVAL##N))!= 0), int>::type );\
\
template <typename U>\
static no_type test(...);\
\
public:\
static const bool value = sizeof(test<T>(0)) == sizeof(yes_type);\
};\
//
BOOST_MOVE_ITERATE_0TO9(BOOST_INTRUSIVE_IS_CONSTRUCTIBLE_IMPL)
#undef BOOST_INTRUSIVE_IS_CONSTRUCTIBLE_IMPL
}// namespace boost_container_is_constructible {
#else
namespace boost_container_is_constructible {
// Example for N == 2
//
//template <typename T, typename P0, typename P1>
//struct is_constructible2
//{
// private:
// template<typename U, typename E = decltype( new U(boost::move_detail::declval<P0>(), boost::move_detail::declval<P1>()) ) >
// static char test( int );
//
// template <typename U>
// static no_type test(...);
//
// public:
// static const bool value = sizeof(test<T>(0)) == sizeof(yes_type);
//};
#define BOOST_INTRUSIVE_IS_CONSTRUCTIBLE_IMPL(N) \
template <typename T BOOST_MOVE_I##N BOOST_MOVE_CLASS##N>\
struct BOOST_MOVE_CAT(is_constructible_impl, N)\
{\
private:\
template <typename U>\
static decltype( new U(BOOST_MOVE_DECLVAL##N), yes_type() ) test(int);\
\
template <typename U>\
static no_type test(...);\
\
public:\
static const bool value = sizeof(test<T>(0)) == sizeof(yes_type);\
};\
//
BOOST_MOVE_ITERATE_0TO9(BOOST_INTRUSIVE_IS_CONSTRUCTIBLE_IMPL)
#undef BOOST_INTRUSIVE_IS_CONSTRUCTIBLE_IMPL
}// namespace boost_container_is_constructible {
#endif
namespace boost {
namespace container {
template<class T, BOOST_MOVE_CLASSDFLT9, class = void>
struct is_constructible;
// Example for N == 2
//
//template <typename T, typename P0, typename P1>
//struct is_constructible
// <T, P0, P1>
// : boost_container_is_constructible::is_constructible_impl2<T, P0, P1>
//{};
#define BOOST_INTRUSIVE_IS_CONSTRUCTIBLE(N) \
template <typename T BOOST_MOVE_I##N BOOST_MOVE_CLASS##N>\
struct is_constructible\
<T BOOST_MOVE_I##N BOOST_MOVE_TARG##N>\
: boost_container_is_constructible::is_constructible_impl##N<T BOOST_MOVE_I##N BOOST_MOVE_TARG##N>\
{};\
//
BOOST_MOVE_ITERATE_0TO9(BOOST_INTRUSIVE_IS_CONSTRUCTIBLE)
#undef BOOST_INTRUSIVE_IS_CONSTRUCTIBLE
} //namespace container {
} //namespace boost {
#endif
#include <boost/interprocess/detail/config_end.hpp>
#endif //BOOST_CONTAINER_DETAIL_IS_CONSTRUCTIBLE_HPP

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test/is_constructible_test.cpp Normal file
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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2025-2025. Distributed under 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/container for documentation.
//
//////////////////////////////////////////////////////////////////////////////
#include <boost/container/detail/is_constructible.hpp>
#include <boost/container/vector.hpp>
struct Point {
int x, y;
Point();
Point(int);
Point(int, int);
Point(int, int, int);
Point(int, int, int, int);
Point(int, int, int, int, int, int, int, int);
};
struct Point2
{
Point2(int*);
};
int main()
{
// 0 args
BOOST_CONTAINER_STATIC_ASSERT((true ==boost::container::is_constructible<Point>::value));
BOOST_CONTAINER_STATIC_ASSERT((true ==boost::container::is_constructible<boost::container::vector<int> >::value));
BOOST_CONTAINER_STATIC_ASSERT((false ==boost::container::is_constructible<Point2>::value));
// 1 args
BOOST_CONTAINER_STATIC_ASSERT((true ==boost::container::is_constructible<Point>::value));
BOOST_CONTAINER_STATIC_ASSERT((true ==boost::container::is_constructible<boost::container::vector<int>, std::size_t>::value));
BOOST_CONTAINER_STATIC_ASSERT((false ==boost::container::is_constructible<boost::container::vector<int>, int*>::value));
BOOST_CONTAINER_STATIC_ASSERT((false ==boost::container::is_constructible<Point, int*>::value));
BOOST_CONTAINER_STATIC_ASSERT((false ==boost::container::is_constructible<Point2, int>::value));
// 2 args
BOOST_CONTAINER_STATIC_ASSERT((true ==boost::container::is_constructible<Point, int, int>::value));
BOOST_CONTAINER_STATIC_ASSERT((true ==boost::container::is_constructible<boost::container::vector<int>, size_t, int>::value));
BOOST_CONTAINER_STATIC_ASSERT((false ==boost::container::is_constructible<Point, int*, int*>::value));
// 3 args
BOOST_CONTAINER_STATIC_ASSERT((true ==boost::container::is_constructible<Point, int, int, int>::value));
BOOST_CONTAINER_STATIC_ASSERT((true ==boost::container::is_constructible<boost::container::vector<int>, int*, int*, boost::container::vector<int>::allocator_type>::value));
BOOST_CONTAINER_STATIC_ASSERT((false ==boost::container::is_constructible<Point, int, int, int*>::value));
// 4 args
BOOST_CONTAINER_STATIC_ASSERT((true ==boost::container::is_constructible<Point, int, int, int, int>::value));
BOOST_CONTAINER_STATIC_ASSERT((false ==boost::container::is_constructible<Point, int, int, int, int*>::value));
// 8 args
BOOST_CONTAINER_STATIC_ASSERT((true ==boost::container::is_constructible<Point, int, int, int, int, int, int, int, int>::value));
BOOST_CONTAINER_STATIC_ASSERT((false ==boost::container::is_constructible<Point, int, int, int, int*, int, int, int, int>::value));
return 0;
}