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/*!
@file
Defines function-like equivalents to the standard `<type_traits>`, and also
to some utilities like `std::declval`.
@copyright Louis Dionne 2013-2017
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
*/
#ifndef BOOST_HANA_TRAITS_HPP
#define BOOST_HANA_TRAITS_HPP
#include <boost/hana/config.hpp>
#include <boost/hana/integral_constant.hpp>
#include <boost/hana/type.hpp>
#include <cstddef>
#include <type_traits>
BOOST_HANA_NAMESPACE_BEGIN namespace traits {
namespace detail {
// We use this instead of hana::integral because we want to return
// hana::integral_constants instead of std::integral_constants.
template <template <typename ...> class F>
struct hana_trait {
template <typename ...T>
constexpr auto operator()(T const& ...) const {
using Result = typename F<typename T::type...>::type;
return hana::integral_c<typename Result::value_type, Result::value>;
}
};
}
///////////////////////
// Type properties
///////////////////////
// Primary type categories
constexpr auto is_void = detail::hana_trait<std::is_void>{};
constexpr auto is_null_pointer = detail::hana_trait<std::is_null_pointer>{};
constexpr auto is_integral = detail::hana_trait<std::is_integral>{};
constexpr auto is_floating_point = detail::hana_trait<std::is_floating_point>{};
constexpr auto is_array = detail::hana_trait<std::is_array>{};
constexpr auto is_enum = detail::hana_trait<std::is_enum>{};
constexpr auto is_union = detail::hana_trait<std::is_union>{};
constexpr auto is_class = detail::hana_trait<std::is_class>{};
constexpr auto is_function = detail::hana_trait<std::is_function>{};
constexpr auto is_pointer = detail::hana_trait<std::is_pointer>{};
constexpr auto is_lvalue_reference = detail::hana_trait<std::is_lvalue_reference>{};
constexpr auto is_rvalue_reference = detail::hana_trait<std::is_rvalue_reference>{};
constexpr auto is_member_object_pointer = detail::hana_trait<std::is_member_object_pointer>{};
constexpr auto is_member_function_pointer = detail::hana_trait<std::is_member_function_pointer>{};
// Composite type categories
constexpr auto is_fundamental = detail::hana_trait<std::is_fundamental>{};
constexpr auto is_arithmetic = detail::hana_trait<std::is_arithmetic>{};
constexpr auto is_scalar = detail::hana_trait<std::is_scalar>{};
constexpr auto is_object = detail::hana_trait<std::is_object>{};
constexpr auto is_compound = detail::hana_trait<std::is_compound>{};
constexpr auto is_reference = detail::hana_trait<std::is_reference>{};
constexpr auto is_member_pointer = detail::hana_trait<std::is_member_pointer>{};
// Type properties
constexpr auto is_const = detail::hana_trait<std::is_const>{};
constexpr auto is_volatile = detail::hana_trait<std::is_volatile>{};
constexpr auto is_trivial = detail::hana_trait<std::is_trivial>{};
constexpr auto is_trivially_copyable = detail::hana_trait<std::is_trivially_copyable>{};
constexpr auto is_standard_layout = detail::hana_trait<std::is_standard_layout>{};
constexpr auto is_pod = detail::hana_trait<std::is_pod>{};
constexpr auto is_literal_type = detail::hana_trait<std::is_literal_type>{};
constexpr auto is_empty = detail::hana_trait<std::is_empty>{};
constexpr auto is_polymorphic = detail::hana_trait<std::is_polymorphic>{};
constexpr auto is_abstract = detail::hana_trait<std::is_abstract>{};
constexpr auto is_signed = detail::hana_trait<std::is_signed>{};
constexpr auto is_unsigned = detail::hana_trait<std::is_unsigned>{};
// Supported operations
constexpr auto is_constructible = detail::hana_trait<std::is_constructible>{};
constexpr auto is_trivially_constructible = detail::hana_trait<std::is_trivially_constructible>{};
constexpr auto is_nothrow_constructible = detail::hana_trait<std::is_nothrow_constructible>{};
constexpr auto is_default_constructible = detail::hana_trait<std::is_default_constructible>{};
constexpr auto is_trivially_default_constructible = detail::hana_trait<std::is_trivially_default_constructible>{};
constexpr auto is_nothrow_default_constructible = detail::hana_trait<std::is_nothrow_default_constructible>{};
constexpr auto is_copy_constructible = detail::hana_trait<std::is_copy_constructible>{};
constexpr auto is_trivially_copy_constructible = detail::hana_trait<std::is_trivially_copy_constructible>{};
constexpr auto is_nothrow_copy_constructible = detail::hana_trait<std::is_nothrow_copy_constructible>{};
constexpr auto is_move_constructible = detail::hana_trait<std::is_move_constructible>{};
constexpr auto is_trivially_move_constructible = detail::hana_trait<std::is_trivially_move_constructible>{};
constexpr auto is_nothrow_move_constructible = detail::hana_trait<std::is_nothrow_move_constructible>{};
constexpr auto is_assignable = detail::hana_trait<std::is_assignable>{};
constexpr auto is_trivially_assignable = detail::hana_trait<std::is_trivially_assignable>{};
constexpr auto is_nothrow_assignable = detail::hana_trait<std::is_nothrow_assignable>{};
constexpr auto is_copy_assignable = detail::hana_trait<std::is_copy_assignable>{};
constexpr auto is_trivially_copy_assignable = detail::hana_trait<std::is_trivially_copy_assignable>{};
constexpr auto is_nothrow_copy_assignable = detail::hana_trait<std::is_nothrow_copy_assignable>{};
constexpr auto is_move_assignable = detail::hana_trait<std::is_move_assignable>{};
constexpr auto is_trivially_move_assignable = detail::hana_trait<std::is_trivially_move_assignable>{};
constexpr auto is_nothrow_move_assignable = detail::hana_trait<std::is_nothrow_move_assignable>{};
constexpr auto is_destructible = detail::hana_trait<std::is_destructible>{};
constexpr auto is_trivially_destructible = detail::hana_trait<std::is_trivially_destructible>{};
constexpr auto is_nothrow_destructible = detail::hana_trait<std::is_nothrow_destructible>{};
constexpr auto has_virtual_destructor = detail::hana_trait<std::has_virtual_destructor>{};
// Property queries
constexpr auto alignment_of = detail::hana_trait<std::alignment_of>{};
constexpr auto rank = detail::hana_trait<std::rank>{};
constexpr struct extent_t {
template <typename T, typename N>
constexpr auto operator()(T const&, N const&) const {
constexpr unsigned n = N::value;
using Result = typename std::extent<typename T::type, n>::type;
return hana::integral_c<typename Result::value_type, Result::value>;
}
template <typename T>
constexpr auto operator()(T const& t) const
{ return (*this)(t, hana::uint_c<0>); }
} extent{};
// Type relationships
constexpr auto is_same = detail::hana_trait<std::is_same>{};
constexpr auto is_base_of = detail::hana_trait<std::is_base_of>{};
constexpr auto is_convertible = detail::hana_trait<std::is_convertible>{};
///////////////////////
// Type modifications
///////////////////////
// Const-volatility specifiers
constexpr auto remove_cv = metafunction<std::remove_cv>;
constexpr auto remove_const = metafunction<std::remove_const>;
constexpr auto remove_volatile = metafunction<std::remove_volatile>;
constexpr auto add_cv = metafunction<std::add_cv>;
constexpr auto add_const = metafunction<std::add_const>;
constexpr auto add_volatile = metafunction<std::add_volatile>;
// References
constexpr auto remove_reference = metafunction<std::remove_reference>;
constexpr auto add_lvalue_reference = metafunction<std::add_lvalue_reference>;
constexpr auto add_rvalue_reference = metafunction<std::add_rvalue_reference>;
// Pointers
constexpr auto remove_pointer = metafunction<std::remove_pointer>;
constexpr auto add_pointer = metafunction<std::add_pointer>;
// Sign modifiers
constexpr auto make_signed = metafunction<std::make_signed>;
constexpr auto make_unsigned = metafunction<std::make_unsigned>;
// Arrays
constexpr auto remove_extent = metafunction<std::remove_extent>;
constexpr auto remove_all_extents = metafunction<std::remove_all_extents>;
// Miscellaneous transformations
constexpr struct aligned_storage_t {
template <typename Len, typename Align>
constexpr auto operator()(Len const&, Align const&) const {
constexpr std::size_t len = Len::value;
constexpr std::size_t align = Align::value;
using Result = typename std::aligned_storage<len, align>::type;
return hana::type_c<Result>;
}
template <typename Len>
constexpr auto operator()(Len const&) const {
constexpr std::size_t len = Len::value;
using Result = typename std::aligned_storage<len>::type;
return hana::type_c<Result>;
}
} aligned_storage{};
constexpr struct aligned_union_t {
template <typename Len, typename ...T>
constexpr auto operator()(Len const&, T const&...) const {
constexpr std::size_t len = Len::value;
using Result = typename std::aligned_union<len, typename T::type...>::type;
return hana::type_c<Result>;
}
} aligned_union{};
constexpr auto decay = metafunction<std::decay>;
// enable_if
// disable_if
// conditional
constexpr auto common_type = metafunction<std::common_type>;
constexpr auto underlying_type = metafunction<std::underlying_type>;
constexpr auto result_of = metafunction<std::result_of>;
///////////////////////
// Utilities
///////////////////////
struct declval_t {
template <typename T>
typename std::add_rvalue_reference<
typename T::type
>::type operator()(T const&) const;
};
constexpr declval_t declval{};
} BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_TRAITS_HPP
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