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1 | /*! |
2 | @file | |
3 | Defines `boost::hana::adjust_if`. | |
4 | ||
b32b8144 | 5 | @copyright Louis Dionne 2013-2017 |
7c673cae FG |
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_IF_HPP | |
11 | #define BOOST_HANA_ADJUST_IF_HPP | |
12 | ||
13 | #include <boost/hana/fwd/adjust_if.hpp> | |
14 | ||
15 | #include <boost/hana/bool.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/if.hpp> | |
20 | #include <boost/hana/transform.hpp> | |
21 | ||
22 | ||
1e59de90 | 23 | namespace boost { namespace hana { |
7c673cae FG |
24 | //! @cond |
25 | template <typename Xs, typename Pred, typename F> | |
26 | constexpr auto adjust_if_t::operator()(Xs&& xs, Pred const& pred, F const& f) const { | |
27 | using S = typename hana::tag_of<Xs>::type; | |
28 | using AdjustIf = BOOST_HANA_DISPATCH_IF(adjust_if_impl<S>, | |
29 | hana::Functor<S>::value | |
30 | ); | |
31 | ||
32 | #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS | |
33 | static_assert(hana::Functor<S>::value, | |
34 | "hana::adjust_if(xs, pred, f) requires 'xs' to be a Functor"); | |
35 | #endif | |
36 | ||
37 | return AdjustIf::apply(static_cast<Xs&&>(xs), pred, f); | |
38 | } | |
39 | //! @endcond | |
40 | ||
41 | namespace detail { | |
42 | template <typename Pred, typename F> | |
43 | struct apply_if { | |
44 | Pred const& pred; | |
45 | F const& f; | |
46 | ||
47 | template <typename X> | |
48 | constexpr decltype(auto) helper(bool cond, X&& x) const | |
49 | { return cond ? f(static_cast<X&&>(x)) : static_cast<X&&>(x); } | |
50 | ||
51 | template <typename X> | |
52 | constexpr decltype(auto) helper(hana::true_, X&& x) const | |
53 | { return f(static_cast<X&&>(x)); } | |
54 | ||
55 | template <typename X> | |
56 | constexpr decltype(auto) helper(hana::false_, X&& x) const | |
57 | { return static_cast<X&&>(x); } | |
58 | ||
59 | ||
60 | template <typename X> | |
61 | constexpr decltype(auto) operator()(X&& x) const { | |
62 | auto cond = hana::if_(pred(x), hana::true_c, hana::false_c); | |
63 | return this->helper(cond, static_cast<X&&>(x)); | |
64 | } | |
65 | }; | |
66 | } | |
67 | ||
68 | template <typename Fun, bool condition> | |
69 | struct adjust_if_impl<Fun, when<condition>> : default_ { | |
70 | template <typename Xs, typename Pred, typename F> | |
71 | static constexpr auto apply(Xs&& xs, Pred const& pred, F const& f) { | |
72 | return hana::transform(static_cast<Xs&&>(xs), | |
73 | detail::apply_if<Pred, F>{pred, f}); | |
74 | } | |
75 | }; | |
1e59de90 | 76 | }} // end namespace boost::hana |
7c673cae FG |
77 | |
78 | #endif // !BOOST_HANA_ADJUST_IF_HPP |