boost/hana/unique.hpp

0001 /*!
0002 @file
0003 Defines `boost::hana::unique`.
0004
0005 Copyright Louis Dionne 2013-2022
0006 Distributed under the Boost Software License, Version 1.0.
0007 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
0008  */
0009
0010 #ifndef BOOST_HANA_UNIQUE_HPP
0011 #define BOOST_HANA_UNIQUE_HPP
0012
0013 #include <boost/hana/fwd/unique.hpp>
0014
0015 #include <boost/hana/concept/sequence.hpp>
0016 #include <boost/hana/config.hpp>
0017 #include <boost/hana/core/dispatch.hpp>
0018 #include <boost/hana/detail/nested_by.hpp> // required by fwd decl
0019 #include <boost/hana/equal.hpp>
0020 #include <boost/hana/front.hpp>
0021 #include <boost/hana/group.hpp>
0022 #include <boost/hana/transform.hpp>
0023
0024
0025 namespace boost { namespace hana {
0026     //! @cond
0027     template <typename Xs>
0028     constexpr auto unique_t::operator()(Xs&& xs) const {
0029         using S = typename hana::tag_of<Xs>::type;
0030         using Unique = BOOST_HANA_DISPATCH_IF(unique_impl<S>,
0031             hana::Sequence<S>::value
0032         );
0033
0034     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
0035         static_assert(hana::Sequence<S>::value,
0036         "hana::unique(xs) requires 'xs' to be a Sequence");
0037     #endif
0038
0039         return Unique::apply(static_cast<Xs&&>(xs));
0040     }
0041
0042     template <typename Xs, typename Predicate>
0043     constexpr auto unique_t::operator()(Xs&& xs, Predicate&& predicate) const {
0044         using S = typename hana::tag_of<Xs>::type;
0045         using Unique = BOOST_HANA_DISPATCH_IF(unique_impl<S>,
0046             hana::Sequence<S>::value
0047         );
0048
0049     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
0050         static_assert(hana::Sequence<S>::value,
0051         "hana::unique(xs, predicate) requires 'xs' to be a Sequence");
0052     #endif
0053
0054         return Unique::apply(static_cast<Xs&&>(xs),
0055                              static_cast<Predicate&&>(predicate));
0056     }
0057     //! @endcond
0058
0059     template <typename S, bool condition>
0060     struct unique_impl<S, when<condition>> : default_ {
0061         template <typename Xs, typename Pred>
0062         static constexpr auto apply(Xs&& xs, Pred&& pred) {
0063             return hana::transform(
0064                 hana::group(static_cast<Xs&&>(xs), static_cast<Pred&&>(pred)),
0065                 hana::front
0066             );
0067         }
0068
0069         template <typename Xs>
0070         static constexpr auto apply(Xs&& xs)
0071         { return unique_impl::apply(static_cast<Xs&&>(xs), hana::equal); }
0072     };
0073 }} // end namespace boost::hana
0074
0075 #endif // !BOOST_HANA_UNIQUE_HPP