optional/detail/experimental_traits.hpp

0001 // Copyright (C) 2017 Andrzej Krzemienski.
0002 //
0003 // Use, modification, and distribution is subject to the Boost Software
0004 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
0005 // http://www.boost.org/LICENSE_1_0.txt)
0006 //
0007 // See http://www.boost.org/libs/optional for documentation.
0008 //
0009 // You are welcome to contact the author at:
0010 //  akrzemi1@gmail.com
0011
0012 #ifndef BOOST_OPTIONAL_DETAIL_EXPERIMENTAL_TRAITS_04NOV2017_HPP
0013 #define BOOST_OPTIONAL_DETAIL_EXPERIMENTAL_TRAITS_04NOV2017_HPP
0014
0015 #include <boost/config.hpp>
0016 #include <boost/detail/workaround.hpp>
0017 #include <boost/predef.h>
0018 #include <boost/type_traits.hpp>
0019
0020 // The condition to use POD implementation
0021
0022 #ifdef BOOST_OPTIONAL_CONFIG_NO_POD_SPEC
0023 # define BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
0024 #elif defined BOOST_OPTIONAL_CONFIG_NO_SPEC_FOR_TRIVIAL_TYPES
0025 # define BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
0026 #elif !defined BOOST_HAS_TRIVIAL_CONSTRUCTOR
0027 # define BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
0028 #elif !defined BOOST_HAS_TRIVIAL_MOVE_ASSIGN
0029 # define BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
0030 #elif !defined BOOST_HAS_TRIVIAL_MOVE_CONSTRUCTOR
0031 # define BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
0032 #elif !defined BOOST_HAS_TRIVIAL_COPY
0033 # define BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
0034 #elif !defined BOOST_HAS_TRIVIAL_ASSIGN
0035 # define BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
0036 #elif !defined BOOST_HAS_TRIVIAL_DESTRUCTOR
0037 # define BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
0038 #elif BOOST_WORKAROUND(BOOST_GCC, < 50000)
0039 # define BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
0040 #endif
0041
0042 // GCC 5 or higher, or clang with libc++ or clang with libstdc++ 5 or higher
0043 #if __cplusplus >= 201103L
0044 #  if BOOST_WORKAROUND(BOOST_GCC, >= 50000)
0045 #    define BOOST_OPTIONAL_DETAIL_USE_STD_TYPE_TRAITS
0046 #  elif (defined BOOST_CLANG)
0047 #    if BOOST_LIB_STD_CXX > 0
0048 #      define BOOST_OPTIONAL_DETAIL_USE_STD_TYPE_TRAITS
0049 #    elif BOOST_LIB_STD_GNU >= 441200023 && BOOST_LIB_STD_GNU != 450600023 && BOOST_LIB_STD_GNU != 450600026 && BOOST_LIB_STD_GNU != 460800003 && BOOST_LIB_STD_GNU != 450400026 && BOOST_LIB_STD_GNU != 460700026
0050 #      define BOOST_OPTIONAL_DETAIL_USE_STD_TYPE_TRAITS
0051 #    endif
0052 #  endif
0053 #endif
0054
0055
0056 #ifndef BOOST_OPTIONAL_DETAIL_USE_STD_TYPE_TRAITS
0057 #  define BOOST_OPTIONAL_DETAIL_HAS_TRIVIAL_CTOR(T) BOOST_HAS_TRIVIAL_CONSTRUCTOR(T)
0058 #else
0059 #  include <type_traits>
0060 #  define BOOST_OPTIONAL_DETAIL_HAS_TRIVIAL_CTOR(T) std::is_trivially_default_constructible<T>::value
0061 #endif
0062
0063
0064 namespace boost { namespace optional_detail {
0065
0066 #ifndef BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
0067 template <typename T>
0068 struct is_type_trivially_copyable
0069   : boost::conditional<(boost::has_trivial_copy_constructor<T>::value &&
0070                         boost::has_trivial_move_constructor<T>::value &&
0071                         boost::has_trivial_destructor<T>::value &&
0072                         boost::has_trivial_move_assign<T>::value &&
0073                         boost::has_trivial_assign<T>::value),
0074                         boost::true_type, boost::false_type>::type
0075 {};
0076 #else
0077 template <typename T>
0078 struct is_type_trivially_copyable
0079 : boost::conditional<(boost::is_scalar<T>::value && !boost::is_const<T>::value && !boost::is_volatile<T>::value),
0080                      boost::true_type, boost::false_type>::type
0081 {};
0082 #endif
0083
0084
0085
0086 #ifndef BOOST_OPTIONAL_DETAIL_NO_SPEC_FOR_TRIVIAL_TYPES
0087 template <typename T>
0088 struct optional_uses_direct_storage_for_
0089   : boost::conditional< (is_type_trivially_copyable<T>::value && BOOST_OPTIONAL_DETAIL_HAS_TRIVIAL_CTOR(T)) ||
0090                         (boost::is_scalar<T>::value && !boost::is_const<T>::value && !boost::is_volatile<T>::value)
0091                       , boost::true_type, boost::false_type>::type
0092 {};
0093 #else
0094 template <typename T>
0095 struct optional_uses_direct_storage_for_
0096   : boost::conditional<(boost::is_scalar<T>::value && !boost::is_const<T>::value && !boost::is_volatile<T>::value)
0097                       , boost::true_type, boost::false_type>::type
0098 {};
0099 #endif
0100
0101
0102 }} // boost::optional_detail
0103
0104 #endif