boost/hana/adjust.hpp

   1 /*!
   2 @file
   3 Defines `boost::hana::adjust`.
   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_ADJUST_HPP
  11 #define BOOST_HANA_ADJUST_HPP
  12
  13 #include <boost/hana/fwd/adjust.hpp>
  14
  15 #include <boost/hana/adjust_if.hpp>
  16 #include <boost/hana/concept/functor.hpp>
  17 #include <boost/hana/config.hpp>
  18 #include <boost/hana/core/dispatch.hpp>
  19 #include <boost/hana/equal.hpp>
  20
  21
  22 BOOST_HANA_NAMESPACE_BEGIN
  23     //! @cond
  24     template <typename Xs, typename Value, typename F>
  25     constexpr auto adjust_t::operator()(Xs&& xs, Value&& value, F&& f) const {
  26         using S = typename hana::tag_of<Xs>::type;
  27         using Adjust = BOOST_HANA_DISPATCH_IF(adjust_impl<S>,
  28             hana::Functor<S>::value
  29         );
  30
  31     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  32         static_assert(hana::Functor<S>::value,
  33         "hana::adjust(xs, value, f) requires 'xs' to be a Functor");
  34     #endif
  35
  36         return Adjust::apply(static_cast<Xs&&>(xs),
  37                              static_cast<Value&&>(value),
  38                              static_cast<F&&>(f));
  39     }
  40     //! @endcond
  41
  42     template <typename Fun, bool condition>
  43     struct adjust_impl<Fun, when<condition>> : default_ {
  44         template <typename Xs, typename Value, typename F>
  45         static constexpr auto apply(Xs&& xs, Value&& value, F&& f) {
  46             return hana::adjust_if(
  47                 static_cast<Xs&&>(xs),
  48                 hana::equal.to(static_cast<Value&&>(value)),
  49                 static_cast<F&&>(f)
  50             );
  51         }
  52     };
  53 BOOST_HANA_NAMESPACE_END
  54
  55 #endif // !BOOST_HANA_ADJUST_HPP