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1 | /*! | |
2 | @file | |
3 | Forward declares `boost::hana::replace_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_REPLACE_IF_HPP | |
11 | #define BOOST_HANA_FWD_REPLACE_IF_HPP | |
12 | ||
13 | #include <boost/hana/config.hpp> | |
14 | #include <boost/hana/core/when.hpp> | |
15 | ||
16 | ||
17 | BOOST_HANA_NAMESPACE_BEGIN | |
18 | //! Replace all the elements of a structure satisfying a `predicate` | |
19 | //! with a fixed value. | |
20 | //! @ingroup group-Functor | |
21 | //! | |
22 | //! | |
23 | //! Signature | |
24 | //! --------- | |
25 | //! Given `F` a Functor and `Bool` a Logical, the signature is | |
26 | //! \f$ | |
27 | //! \mathtt{replace_if} : F(T) \times (T \to Bool) \times T \to F(T) | |
28 | //! \f$ | |
29 | //! | |
30 | //! @param xs | |
31 | //! The structure to replace elements of. | |
32 | //! | |
33 | //! @param predicate | |
34 | //! A function called as `predicate(x)` for element(s) `x` of the | |
35 | //! structure and returning a `Logical` representing whether `x` | |
36 | //! should be replaced by `value`. | |
37 | //! | |
38 | //! @param value | |
39 | //! A value by which every element `x` of the structure for which | |
40 | //! `predicate` returns a true-valued `Logical` is replaced. | |
41 | //! | |
42 | //! | |
43 | //! Example | |
44 | //! ------- | |
45 | //! @include example/replace_if.cpp | |
46 | #ifdef BOOST_HANA_DOXYGEN_INVOKED | |
47 | constexpr auto replace_if = [](auto&& xs, auto&& predicate, auto&& value) { | |
48 | return tag-dispatched; | |
49 | }; | |
50 | #else | |
51 | template <typename Xs, typename = void> | |
52 | struct replace_if_impl : replace_if_impl<Xs, when<true>> { }; | |
53 | ||
54 | struct replace_if_t { | |
55 | template <typename Xs, typename Pred, typename Value> | |
56 | constexpr auto operator()(Xs&& xs, Pred&& pred, Value&& value) const; | |
57 | }; | |
58 | ||
59 | constexpr replace_if_t replace_if{}; | |
60 | #endif | |
61 | BOOST_HANA_NAMESPACE_END | |
62 | ||
63 | #endif // !BOOST_HANA_FWD_REPLACE_IF_HPP |