boost/hana/unique.hpp

   1 /*!
   2 @file
   3 Defines `boost::hana::unique`.
   4
   5 @copyright Louis Dionne 2013-2017
   6 Distributed under the Boost Software License, Version 1.0.
   7 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   8  */
   9
  10 #ifndef BOOST_HANA_UNIQUE_HPP
  11 #define BOOST_HANA_UNIQUE_HPP
  12
  13 #include <boost/hana/fwd/unique.hpp>
  14
  15 #include <boost/hana/concept/sequence.hpp>
  16 #include <boost/hana/config.hpp>
  17 #include <boost/hana/core/dispatch.hpp>
  18 #include <boost/hana/detail/nested_by.hpp> // required by fwd decl
  19 #include <boost/hana/equal.hpp>
  20 #include <boost/hana/front.hpp>
  21 #include <boost/hana/group.hpp>
  22 #include <boost/hana/transform.hpp>
  23
  24
  25 BOOST_HANA_NAMESPACE_BEGIN
  26     //! @cond
  27     template <typename Xs>
  28     constexpr auto unique_t::operator()(Xs&& xs) const {
  29         using S = typename hana::tag_of<Xs>::type;
  30         using Unique = BOOST_HANA_DISPATCH_IF(unique_impl<S>,
  31             hana::Sequence<S>::value
  32         );
  33
  34     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  35         static_assert(hana::Sequence<S>::value,
  36         "hana::unique(xs) requires 'xs' to be a Sequence");
  37     #endif
  38
  39         return Unique::apply(static_cast<Xs&&>(xs));
  40     }
  41
  42     template <typename Xs, typename Predicate>
  43     constexpr auto unique_t::operator()(Xs&& xs, Predicate&& predicate) const {
  44         using S = typename hana::tag_of<Xs>::type;
  45         using Unique = BOOST_HANA_DISPATCH_IF(unique_impl<S>,
  46             hana::Sequence<S>::value
  47         );
  48
  49     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  50         static_assert(hana::Sequence<S>::value,
  51         "hana::unique(xs, predicate) requires 'xs' to be a Sequence");
  52     #endif
  53
  54         return Unique::apply(static_cast<Xs&&>(xs),
  55                              static_cast<Predicate&&>(predicate));
  56     }
  57     //! @endcond
  58
  59     template <typename S, bool condition>
  60     struct unique_impl<S, when<condition>> : default_ {
  61         template <typename Xs, typename Pred>
  62         static constexpr auto apply(Xs&& xs, Pred&& pred) {
  63             return hana::transform(
  64                 hana::group(static_cast<Xs&&>(xs), static_cast<Pred&&>(pred)),
  65                 hana::front
  66             );
  67         }
  68
  69         template <typename Xs>
  70         static constexpr auto apply(Xs&& xs)
  71         { return unique_impl::apply(static_cast<Xs&&>(xs), hana::equal); }
  72     };
  73 BOOST_HANA_NAMESPACE_END
  74
  75 #endif // !BOOST_HANA_UNIQUE_HPP