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Diffstat (limited to 'boost/hana/detail/any_of.hpp')
-rw-r--r-- | boost/hana/detail/any_of.hpp | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/boost/hana/detail/any_of.hpp b/boost/hana/detail/any_of.hpp new file mode 100644 index 0000000000..89c0d6a544 --- /dev/null +++ b/boost/hana/detail/any_of.hpp @@ -0,0 +1,46 @@ +/*! +@file +Defines `boost::hana::detail::any_of`. + +@copyright Louis Dionne 2013-2016 +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_DETAIL_ANY_OF_HPP +#define BOOST_HANA_DETAIL_ANY_OF_HPP + +#include <boost/hana/config.hpp> + +#include <type_traits> +#include <utility> + + +BOOST_HANA_NAMESPACE_BEGIN namespace detail { + std::false_type expand(...); + + template <template <typename ...> class Predicate, typename ...T> + decltype(expand( + typename std::enable_if<!Predicate<T>::value, void*>::type{}... + )) any_of_impl(int); + + template <template <typename ...> class Predicate, typename ...T> + std::true_type any_of_impl(...); + + //! @ingroup group-details + //! Returns whether the `Predicate` is satisfied by any of the `T...`. + //! + //! This metafunction will short-circuit the evaluation at the first + //! type satisfying the predicate, if such a type exists. + //! + //! + //! @note + //! The implementation technique used here was originally shown to + //! me by Eric Fiselier. All credits where due. + template <template <typename ...> class Predicate, typename ...T> + struct any_of + : decltype(any_of_impl<Predicate, T...>(int{})) + { }; +} BOOST_HANA_NAMESPACE_END + +#endif // !BOOST_HANA_DETAIL_ANY_OF_HPP |