[857] | 1 |
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| 2 | // (C) Copyright Steve Cleary, Beman Dawes, Howard Hinnant & John Maddock 2000.
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| 3 | // Use, modification and distribution are subject to the Boost Software License,
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| 4 | // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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| 5 | // http://www.boost.org/LICENSE_1_0.txt).
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| 6 | //
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| 7 | // See http://www.boost.org/libs/type_traits for most recent version including documentation.
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| 8 |
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| 9 | #ifndef BOOST_TT_IS_EMPTY_HPP_INCLUDED
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| 10 | #define BOOST_TT_IS_EMPTY_HPP_INCLUDED
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| 11 |
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| 12 | #include "boost/type_traits/is_convertible.hpp"
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| 13 | #include "boost/type_traits/detail/ice_or.hpp"
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| 14 | #include "boost/type_traits/config.hpp"
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| 15 | #include "boost/type_traits/intrinsics.hpp"
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| 16 |
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| 17 | #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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| 18 | # include "boost/type_traits/remove_cv.hpp"
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| 19 | # include "boost/type_traits/is_class.hpp"
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| 20 | # include "boost/type_traits/add_reference.hpp"
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| 21 | #else
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| 22 | # include "boost/type_traits/is_reference.hpp"
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| 23 | # include "boost/type_traits/is_pointer.hpp"
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| 24 | # include "boost/type_traits/is_member_pointer.hpp"
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| 25 | # include "boost/type_traits/is_array.hpp"
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| 26 | # include "boost/type_traits/is_void.hpp"
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| 27 | # include "boost/type_traits/detail/ice_and.hpp"
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| 28 | # include "boost/type_traits/detail/ice_not.hpp"
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| 29 | #endif
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| 30 |
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| 31 | // should be always the last #include directive
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| 32 | #include "boost/type_traits/detail/bool_trait_def.hpp"
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| 33 |
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| 34 | namespace boost {
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| 35 |
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| 36 | namespace detail {
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| 37 |
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| 38 | #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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| 39 | template <typename T>
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| 40 | struct empty_helper_t1 : public T
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| 41 | {
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| 42 | empty_helper_t1(); // hh compiler bug workaround
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| 43 | int i[256];
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| 44 | };
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| 45 |
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| 46 | struct empty_helper_t2 { int i[256]; };
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| 47 |
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| 48 | #if !BOOST_WORKAROUND(__BORLANDC__, < 0x600)
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| 49 |
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| 50 | template <typename T, bool is_a_class = false>
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| 51 | struct empty_helper
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| 52 | {
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| 53 | BOOST_STATIC_CONSTANT(bool, value = false);
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| 54 | };
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| 55 |
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| 56 | template <typename T>
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| 57 | struct empty_helper<T, true>
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| 58 | {
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| 59 | BOOST_STATIC_CONSTANT(
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| 60 | bool, value = (sizeof(empty_helper_t1<T>) == sizeof(empty_helper_t2))
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| 61 | );
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| 62 | };
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| 63 |
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| 64 | template <typename T>
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| 65 | struct is_empty_impl
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| 66 | {
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| 67 | typedef typename remove_cv<T>::type cvt;
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| 68 | BOOST_STATIC_CONSTANT(
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| 69 | bool, value = (
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| 70 | ::boost::type_traits::ice_or<
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| 71 | ::boost::detail::empty_helper<cvt,::boost::is_class<T>::value>::value
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| 72 | , BOOST_IS_EMPTY(cvt)
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| 73 | >::value
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| 74 | ));
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| 75 | };
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| 76 |
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| 77 | #else // __BORLANDC__
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| 78 |
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| 79 | template <typename T, bool is_a_class, bool convertible_to_int>
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| 80 | struct empty_helper
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| 81 | {
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| 82 | BOOST_STATIC_CONSTANT(bool, value = false);
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| 83 | };
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| 84 |
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| 85 | template <typename T>
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| 86 | struct empty_helper<T, true, false>
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| 87 | {
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| 88 | BOOST_STATIC_CONSTANT(bool, value = (
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| 89 | sizeof(empty_helper_t1<T>) == sizeof(empty_helper_t2)
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| 90 | ));
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| 91 | };
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| 92 |
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| 93 | template <typename T>
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| 94 | struct is_empty_impl
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| 95 | {
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| 96 | typedef typename remove_cv<T>::type cvt;
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| 97 | typedef typename add_reference<T>::type r_type;
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| 98 |
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| 99 | BOOST_STATIC_CONSTANT(
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| 100 | bool, value = (
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| 101 | ::boost::type_traits::ice_or<
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| 102 | ::boost::detail::empty_helper<
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| 103 | cvt
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| 104 | , ::boost::is_class<T>::value
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| 105 | , ::boost::is_convertible< r_type,int>::value
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| 106 | >::value
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| 107 | , BOOST_IS_EMPTY(cvt)
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| 108 | >::value));
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| 109 | };
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| 110 |
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| 111 | #endif // __BORLANDC__
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| 112 |
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| 113 | #else // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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| 114 |
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| 115 | #ifdef BOOST_MSVC6_MEMBER_TEMPLATES
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| 116 |
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| 117 | template <typename T>
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| 118 | struct empty_helper_t1 : public T
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| 119 | {
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| 120 | empty_helper_t1();
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| 121 | int i[256];
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| 122 | };
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| 123 |
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| 124 | struct empty_helper_t2 { int i[256]; };
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| 125 |
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| 126 | template <typename T>
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| 127 | struct empty_helper_base
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| 128 | {
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| 129 | enum { value = (sizeof(empty_helper_t1<T>) == sizeof(empty_helper_t2)) };
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| 130 | };
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| 131 |
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| 132 | template <typename T>
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| 133 | struct empty_helper_nonbase
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| 134 | {
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| 135 | enum { value = false };
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| 136 | };
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| 137 |
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| 138 | template <bool base>
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| 139 | struct empty_helper_chooser
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| 140 | {
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| 141 | template <typename T> struct result_
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| 142 | {
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| 143 | typedef empty_helper_nonbase<T> type;
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| 144 | };
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| 145 | };
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| 146 |
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| 147 | template <>
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| 148 | struct empty_helper_chooser<true>
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| 149 | {
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| 150 | template <typename T> struct result_
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| 151 | {
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| 152 | typedef empty_helper_base<T> type;
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| 153 | };
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| 154 | };
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| 155 |
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| 156 | template <typename T>
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| 157 | struct is_empty_impl
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| 158 | {
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| 159 | typedef ::boost::detail::empty_helper_chooser<
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| 160 | ::boost::type_traits::ice_and<
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| 161 | ::boost::type_traits::ice_not< ::boost::is_reference<T>::value >::value,
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| 162 | ::boost::type_traits::ice_not< ::boost::is_convertible<T,double>::value >::value,
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| 163 | ::boost::type_traits::ice_not< ::boost::is_pointer<T>::value >::value,
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| 164 | ::boost::type_traits::ice_not< ::boost::is_member_pointer<T>::value >::value,
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| 165 | ::boost::type_traits::ice_not< ::boost::is_array<T>::value >::value,
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| 166 | ::boost::type_traits::ice_not< ::boost::is_void<T>::value >::value,
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| 167 | ::boost::type_traits::ice_not<
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| 168 | ::boost::is_convertible<T,void const volatile*>::value
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| 169 | >::value
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| 170 | >::value > chooser;
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| 171 |
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| 172 | typedef typename chooser::template result_<T> result;
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| 173 | typedef typename result::type eh_type;
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| 174 |
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| 175 | BOOST_STATIC_CONSTANT(bool, value =
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| 176 | (::boost::type_traits::ice_or<eh_type::value, BOOST_IS_EMPTY(T)>::value));
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| 177 | };
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| 178 |
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| 179 | #else
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| 180 |
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| 181 | template <typename T> struct is_empty_impl
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| 182 | {
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| 183 | BOOST_STATIC_CONSTANT(bool, value = BOOST_IS_EMPTY(T));
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| 184 | };
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| 185 |
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| 186 | #endif // BOOST_MSVC6_MEMBER_TEMPLATES
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| 187 |
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| 188 | #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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| 189 |
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| 190 | // these help when the compiler has no partial specialization support:
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| 191 | BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void,false)
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| 192 | #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS
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| 193 | BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void const,false)
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| 194 | BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void volatile,false)
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| 195 | BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void const volatile,false)
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| 196 | #endif
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| 197 |
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| 198 | } // namespace detail
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| 199 |
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| 200 | BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_empty,T,::boost::detail::is_empty_impl<T>::value)
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| 201 |
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| 202 | } // namespace boost
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| 203 |
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| 204 | #include "boost/type_traits/detail/bool_trait_undef.hpp"
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| 205 |
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| 206 | #endif // BOOST_TT_IS_EMPTY_HPP_INCLUDED
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| 207 |
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