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Add SFINAE helpers to type_traits.hpp

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This commit is contained in:
Christian Mazakas
2022-11-07 12:55:28 -08:00
parent 551456c0c5
commit 867e60113b
2 changed files with 50 additions and 12 deletions
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12
include/boost/unordered/detail/implementation.hpp
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@ -182,18 +182,6 @@
#endif
#endif
// BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
#if !defined(BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES)
#if BOOST_COMP_CLANG && __cplusplus >= 201703
#define BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES 1
#endif
#endif
#if !defined(BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES)
#define BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES 0
#endif
namespace boost {
namespace unordered {
namespace detail {

50
include/boost/unordered/detail/type_traits.hpp
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@ -14,6 +14,25 @@
#include <boost/type_traits/integral_constant.hpp>
#include <boost/type_traits/is_convertible.hpp>
#include <boost/type_traits/make_void.hpp>
#include <boost/type_traits/type_identity.hpp>
#if !defined(BOOST_NO_CXX17_DEDUCTION_GUIDES)
#include <boost/type_traits/enable_if.hpp>
#include <boost/type_traits/is_integral.hpp>
#include <boost/type_traits/remove_const.hpp>
#endif
// BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
#if !defined(BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES)
#if !defined(BOOST_NO_CXX17_DEDUCTION_GUIDES)
#define BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES 1
#endif
#endif
#if !defined(BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES)
#define BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES 0
#endif
namespace boost {
namespace unordered {
@ -52,6 +71,37 @@ namespace boost {
!boost::is_convertible<Key, iterator>::value &&
!boost::is_convertible<Key, const_iterator>::value;
};
#if BOOST_UNORDERED_TEMPLATE_DEDUCTION_GUIDES
// https://eel.is/c++draft/container.requirements#container.alloc.reqmts-34
// https://eel.is/c++draft/container.requirements#unord.req.general-243
template <class InputIterator>
constexpr bool const is_input_iterator_v =
!boost::is_integral<InputIterator>::value;
template <class A, class = void> struct is_allocator
{
constexpr static bool const value = false;
};
template <class A>
struct is_allocator<A,
boost::void_t<typename A::value_type,
decltype(std::declval<A&>().allocate(std::size_t{}))> >
{
constexpr static bool const value = true;
};
template <class A>
constexpr bool const is_allocator_v = is_allocator<A>::value;
template <class H>
constexpr bool const is_hash_v =
!boost::is_integral<H>::value && !is_allocator_v<H>;
template <class P> constexpr bool const is_pred_v = !is_allocator_v<P>;
#endif
} // namespace detail
} // namespace unordered
} // namespace boost