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- /*!
- @file
- Defines `boost::hana::unique`.
- @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_UNIQUE_HPP
- #define BOOST_HANA_UNIQUE_HPP
- #include <boost/hana/fwd/unique.hpp>
- #include <boost/hana/concept/sequence.hpp>
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/dispatch.hpp>
- #include <boost/hana/detail/nested_by.hpp> // required by fwd decl
- #include <boost/hana/equal.hpp>
- #include <boost/hana/front.hpp>
- #include <boost/hana/group.hpp>
- #include <boost/hana/transform.hpp>
- BOOST_HANA_NAMESPACE_BEGIN
- //! @cond
- template <typename Xs>
- constexpr auto unique_t::operator()(Xs&& xs) const {
- using S = typename hana::tag_of<Xs>::type;
- using Unique = BOOST_HANA_DISPATCH_IF(unique_impl<S>,
- hana::Sequence<S>::value
- );
- #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
- static_assert(hana::Sequence<S>::value,
- "hana::unique(xs) requires 'xs' to be a Sequence");
- #endif
- return Unique::apply(static_cast<Xs&&>(xs));
- }
- template <typename Xs, typename Predicate>
- constexpr auto unique_t::operator()(Xs&& xs, Predicate&& predicate) const {
- using S = typename hana::tag_of<Xs>::type;
- using Unique = BOOST_HANA_DISPATCH_IF(unique_impl<S>,
- hana::Sequence<S>::value
- );
- #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
- static_assert(hana::Sequence<S>::value,
- "hana::unique(xs, predicate) requires 'xs' to be a Sequence");
- #endif
- return Unique::apply(static_cast<Xs&&>(xs),
- static_cast<Predicate&&>(predicate));
- }
- //! @endcond
- template <typename S, bool condition>
- struct unique_impl<S, when<condition>> : default_ {
- template <typename Xs, typename Pred>
- static constexpr auto apply(Xs&& xs, Pred&& pred) {
- return hana::transform(
- hana::group(static_cast<Xs&&>(xs), static_cast<Pred&&>(pred)),
- hana::front
- );
- }
- template <typename Xs>
- static constexpr auto apply(Xs&& xs)
- { return unique_impl::apply(static_cast<Xs&&>(xs), hana::equal); }
- };
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_UNIQUE_HPP
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