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1 | /*! |
2 | @file | |
3 | Forward declares `boost::hana::adjust_if`. | |
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_FWD_ADJUST_IF_HPP | |
11 | #define BOOST_HANA_FWD_ADJUST_IF_HPP | |
12 | ||
13 | #include <boost/hana/config.hpp> | |
14 | #include <boost/hana/core/when.hpp> | |
15 | ||
16 | ||
17 | BOOST_HANA_NAMESPACE_BEGIN | |
18 | //! Apply a function on all the elements of a structure satisfying a predicate. | |
19 | //! @ingroup group-Functor | |
20 | //! | |
21 | //! Given a Functor, a predicate `pred` and a function `f`, `adjust_if` | |
22 | //! will _adjust_ the elements of the Functor that satisfy the predicate | |
23 | //! with the function `f`. In other words, `adjust_if` will return a new | |
24 | //! Functor equal to the original one, except that the elements satisfying | |
25 | //! the predicate will be transformed with the given function. Elements | |
26 | //! for which the predicate is not satisfied are left untouched, and they | |
27 | //! are kept as-is in the resulting Functor. | |
28 | //! | |
29 | //! | |
30 | //! Signature | |
31 | //! --------- | |
32 | //! Given a `Functor` `F` and a `Logical` `Bool`, the signature is | |
33 | //! \f$ | |
34 | //! \mathtt{adjust_if} : F(T) \times (T \to Bool) \times (T \to T) \to F(T) | |
35 | //! \f$ | |
36 | //! | |
37 | //! @param xs | |
38 | //! The structure to adjust with `f`. | |
39 | //! | |
40 | //! @param pred | |
41 | //! A function called as `pred(x)` for each element of the Functor, | |
42 | //! and returning whether `f` should be applied on that element. | |
43 | //! | |
44 | //! @param f | |
45 | //! A function called as `f(x)` on the element(s) of the Functor that | |
46 | //! satisfy the predicate. | |
47 | //! | |
48 | //! | |
49 | //! Example | |
50 | //! ------- | |
51 | //! @include example/adjust_if.cpp | |
52 | #ifdef BOOST_HANA_DOXYGEN_INVOKED | |
53 | constexpr auto adjust_if = [](auto&& xs, auto const& pred, auto const& f) { | |
54 | return tag-dispatched; | |
55 | }; | |
56 | #else | |
57 | template <typename Xs, typename = void> | |
58 | struct adjust_if_impl : adjust_if_impl<Xs, when<true>> { }; | |
59 | ||
60 | struct adjust_if_t { | |
61 | template <typename Xs, typename Pred, typename F> | |
62 | constexpr auto operator()(Xs&& xs, Pred const& pred, F const& f) const; | |
63 | }; | |
64 | ||
65 | constexpr adjust_if_t adjust_if{}; | |
66 | #endif | |
67 | BOOST_HANA_NAMESPACE_END | |
68 | ||
69 | #endif // !BOOST_HANA_FWD_ADJUST_IF_HPP |