ceph/src/boost/libs/hana/include/boost/hana/find.hpp

   1 /*!
   2 @file
   3 Defines `boost::hana::find`.
   4
   5 @copyright Louis Dionne 2013-2016
   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_FIND_HPP
  11 #define BOOST_HANA_FIND_HPP
  12
  13 #include <boost/hana/fwd/find.hpp>
  14
  15 #include <boost/hana/concept/searchable.hpp>
  16 #include <boost/hana/config.hpp>
  17 #include <boost/hana/core/dispatch.hpp>
  18 #include <boost/hana/equal.hpp>
  19 #include <boost/hana/find_if.hpp>
  20
  21
  22 BOOST_HANA_NAMESPACE_BEGIN
  23     //! @cond
  24     template <typename Xs, typename Key>
  25     constexpr auto find_t::operator()(Xs&& xs, Key const& key) const {
  26         using S = typename hana::tag_of<Xs>::type;
  27         using Find = BOOST_HANA_DISPATCH_IF(find_impl<S>,
  28             hana::Searchable<S>::value
  29         );
  30
  31     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  32         static_assert(hana::Searchable<S>::value,
  33         "hana::find(xs, key) requires 'xs' to be Searchable");
  34     #endif
  35
  36         return Find::apply(static_cast<Xs&&>(xs), key);
  37     }
  38     //! @endcond
  39
  40     namespace detail {
  41         template <typename T>
  42         struct equal_to {
  43             T const& t;
  44             template <typename U>
  45             constexpr auto operator()(U const& u) const {
  46                 return hana::equal(t, u);
  47             }
  48         };
  49     }
  50
  51     template <typename S, bool condition>
  52     struct find_impl<S, when<condition>> : default_ {
  53         template <typename Xs, typename Key>
  54         static constexpr auto apply(Xs&& xs, Key const& key) {
  55             return hana::find_if(static_cast<Xs&&>(xs),
  56                                  detail::equal_to<Key>{key});
  57         }
  58     };
  59 BOOST_HANA_NAMESPACE_END
  60
  61 #endif // !BOOST_HANA_FIND_HPP