mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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107 lines
3.6 KiB
C++
107 lines
3.6 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2016 Bolero MURAKAMI
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https://github.com/bolero-MURAKAMI/Sprout
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef SPROUT_TUPLE_TUPLE_TUPLE_ELEMENT_HPP
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#define SPROUT_TUPLE_TUPLE_TUPLE_ELEMENT_HPP
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#include <type_traits>
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#include <tuple>
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#include <sprout/config.hpp>
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#include <sprout/workaround/std/cstddef.hpp>
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#include <sprout/type_traits/integral_constant.hpp>
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#include <sprout/type_traits/has_type.hpp>
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#include <sprout/type_traits/has_value.hpp>
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#include <sprout/detail/nil_base.hpp>
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namespace sprout {
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namespace tuples {
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//
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// tuple_element
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//
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namespace detail {
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#if defined(_MSC_VER)
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template<std::size_t I, typename T, bool = true>
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#else
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template<std::size_t I, typename T, bool = sprout::has_value<std::tuple_size<T> >::value>
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#endif
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struct valid_tuple_index;
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template<std::size_t I, typename T>
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struct valid_tuple_index<I, T, false>
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: public sprout::false_type
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{};
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template<std::size_t I, typename T>
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struct valid_tuple_index<I, T, true>
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: public sprout::bool_constant<(I < std::tuple_size<T>::value)>
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{};
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#if defined(_MSC_VER)
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template<std::size_t I, typename T, bool = true>
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#else
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template<std::size_t I, typename T, bool = sprout::has_type<std::tuple_element<I, T> >::value && sprout::tuples::detail::valid_tuple_index<I, T>::value>
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#endif
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struct tuple_element_default;
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template<std::size_t I, typename T>
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struct tuple_element_default<I, T, false>
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: public sprout::detail::nil_base
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{};
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template<std::size_t I, typename T>
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struct tuple_element_default<I, T, true>
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: public std::tuple_element<I, T>
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{};
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} // namespace detail
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template<std::size_t I, typename T>
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struct tuple_element
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: public sprout::tuples::detail::tuple_element_default<I, T>
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{};
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namespace detail {
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template<std::size_t I, typename T>
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struct tuple_element_default<I, T const, true>
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: public std::add_const<
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typename sprout::tuples::tuple_element<I, T>::type
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>
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{};
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template<std::size_t I, typename T>
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struct tuple_element_default<I, T volatile, true>
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: public std::add_volatile<
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typename sprout::tuples::tuple_element<I, T>::type
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>
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{};
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template<std::size_t I, typename T>
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struct tuple_element_default<I, T const volatile, true>
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: public std::add_cv<
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typename sprout::tuples::tuple_element<I, T>::type
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>
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{};
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} // namespace detail
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template<std::size_t I, typename T>
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struct tuple_element<I, T const>
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: public sprout::tuples::detail::tuple_element_default<I, T const>
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{};
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template<std::size_t I, typename T>
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struct tuple_element<I, T volatile>
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: public sprout::tuples::detail::tuple_element_default<I, T volatile>
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{};
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template<std::size_t I, typename T>
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struct tuple_element<I, T const volatile>
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: public sprout::tuples::detail::tuple_element_default<I, T const volatile>
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{};
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} // namespace tuples
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using sprout::tuples::tuple_element;
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#if SPROUT_USE_TEMPLATE_ALIASES
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namespace tuples {
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template<std::size_t I, typename T>
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using tuple_element_t = typename sprout::tuples::tuple_element<I, T>::type;
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} // namespace tuples
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using sprout::tuples::tuple_element_t;
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#endif // #if SPROUT_USE_TEMPLATE_ALIASES
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} // namespace sprout
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#endif // #ifndef SPROUT_TUPLE_TUPLE_TUPLE_ELEMENT_HPP
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