47 lines
1.4 KiB
C++
47 lines
1.4 KiB
C++
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/*!
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@file
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Defines `boost::hana::detail::any_of`.
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@copyright Louis Dionne 2013-2016
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_DETAIL_ANY_OF_HPP
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#define BOOST_HANA_DETAIL_ANY_OF_HPP
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#include <boost/hana/config.hpp>
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#include <type_traits>
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#include <utility>
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BOOST_HANA_NAMESPACE_BEGIN namespace detail {
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std::false_type expand(...);
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template <template <typename ...> class Predicate, typename ...T>
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decltype(expand(
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typename std::enable_if<!Predicate<T>::value, void*>::type{}...
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)) any_of_impl(int);
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template <template <typename ...> class Predicate, typename ...T>
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std::true_type any_of_impl(...);
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//! @ingroup group-details
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//! Returns whether the `Predicate` is satisfied by any of the `T...`.
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//!
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//! This metafunction will short-circuit the evaluation at the first
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//! type satisfying the predicate, if such a type exists.
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//!
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//!
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//! @note
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//! The implementation technique used here was originally shown to
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//! me by Eric Fiselier. All credits where due.
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template <template <typename ...> class Predicate, typename ...T>
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struct any_of
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: decltype(any_of_impl<Predicate, T...>(int{}))
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{ };
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} BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_DETAIL_ANY_OF_HPP
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