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1 | /*! |
2 | @file | |
3 | Defines `boost::hana::replace`. | |
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_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> | |
25 | 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) | |
46 | 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 |