projects / ceph.git / blame
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|---|---|---|
| 7c673cae FG |
1 | /*! |
| 2 | @file | |
| 3 | Forward declares `boost::hana::remove_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_REMOVE_IF_HPP | |
| 11 | #define BOOST_HANA_FWD_REMOVE_IF_HPP | |
| 12 | ||
| 13 | #include <boost/hana/config.hpp> | |
| 14 | #include <boost/hana/core/when.hpp> | |
| 15 | ||
| 16 | ||
| 17 | BOOST_HANA_NAMESPACE_BEGIN | |
| 18 | //! Remove all the elements of a monadic structure that satisfy some | |
| 19 | //! predicate. | |
| 20 | //! @ingroup group-MonadPlus | |
| 21 | //! | |
| 22 | //! Given a monadic structure `xs` and a unary predicate, `remove_if` | |
| 23 | //! returns a new monadic structure equal to `xs` without all its elements | |
| 24 | //! that satisfy the predicate. This is equivalent to `filter` with a | |
| 25 | //! negated predicate, i.e. | |
| 26 | //! @code | |
| 27 | //! remove_if(xs, predicate) == filter(xs, negated predicated) | |
| 28 | //! @endcode | |
| 29 | //! | |
| 30 | //! | |
| 31 | //! Signature | |
| 32 | //! --------- | |
| 33 | //! Given a MonadPlus `M` and a predicate of type \f$ T \to Bool \f$ for | |
| 34 | //! some compile-time Logical `Bool`, the signature is | |
| 35 | //! \f$ | |
| 36 | //! \mathrm{remove\_if} : M(T) \times (T \to Bool) \to M(T) | |
| 37 | //! \f$ | |
| 38 | //! | |
| 39 | //! @param xs | |
| 40 | //! A monadic structure to remove some elements from. | |
| 41 | //! | |
| 42 | //! @param predicate | |
| 43 | //! A unary predicate called as `predicate(x)`, where `x` is an element | |
| 44 | //! of the structure, and returning whether `x` should be removed from | |
| 45 | //! the structure. In the current version of the library, `predicate` | |
| 46 | //! must return a compile-time Logical. | |
| 47 | //! | |
| 48 | //! | |
| 49 | //! Example | |
| 50 | //! ------- | |
| 51 | //! @include example/remove_if.cpp | |
| 52 | #ifdef BOOST_HANA_DOXYGEN_INVOKED | |
| 53 | constexpr auto remove_if = [](auto&& xs, auto&& predicate) { | |
| 54 | return tag-dispatched; | |
| 55 | }; | |
| 56 | #else | |
| 57 | template <typename M, typename = void> | |
| 58 | struct remove_if_impl : remove_if_impl<M, when<true>> { }; | |
| 59 | ||
| 60 | struct remove_if_t { | |
| 61 | template <typename Xs, typename Pred> | |
| 62 | constexpr auto operator()(Xs&& xs, Pred&& pred) const; | |
| 63 | }; | |
| 64 | ||
| 65 | constexpr remove_if_t remove_if{}; | |
| 66 | #endif | |
| 67 | BOOST_HANA_NAMESPACE_END | |
| 68 | ||
| 69 | #endif // !BOOST_HANA_FWD_REMOVE_IF_HPP |