1 /*! 2 @file 3 Defines `boost::hana::replace`. 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_REPLACE_HPP 11 #define BOOST_HANA_REPLACE_HPP 12 13 #include <boost/hana/fwd/replace.hpp> 14 15 #include <boost/hana/concept/functor.hpp> 16 #include <boost/hana/config.hpp> 17 #include <boost/hana/core/dispatch.hpp> 18 #include <boost/hana/equal.hpp> 19 #include <boost/hana/replace_if.hpp> 20 21 22 BOOST_HANA_NAMESPACE_BEGIN 23 //! @cond 24 template <typename Xs, typename OldVal, typename NewVal> operator ()(Xs && xs,OldVal && oldval,NewVal && newval) const25 constexpr auto replace_t::operator()(Xs&& xs, OldVal&& oldval, NewVal&& newval) const { 26 using S = typename hana::tag_of<Xs>::type; 27 using Replace = BOOST_HANA_DISPATCH_IF(replace_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::replace(xs, oldval, newval) requires 'xs' to be a Functor"); 34 #endif 35 36 return Replace::apply(static_cast<Xs&&>(xs), 37 static_cast<OldVal&&>(oldval), 38 static_cast<NewVal&&>(newval)); 39 } 40 //! @endcond 41 42 template <typename Fun, bool condition> 43 struct replace_impl<Fun, when<condition>> : default_ { 44 template <typename Xs, typename OldVal, typename NewVal> 45 static constexpr decltype(auto) applyreplace_impl46 apply(Xs&& xs, OldVal&& oldval, NewVal&& newval) { 47 return hana::replace_if( 48 static_cast<Xs&&>(xs), 49 hana::equal.to(static_cast<OldVal&&>(oldval)), 50 static_cast<NewVal&&>(newval) 51 ); 52 } 53 }; 54 BOOST_HANA_NAMESPACE_END 55 56 #endif // !BOOST_HANA_REPLACE_HPP 57