ceph/src/boost/libs/hana/include/boost/hana/fwd/remove_at.hpp

   1 /*!
   2 @file
   3 Forward declares `boost::hana::remove_at` and `boost::hana::remove_at_c`.
   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_AT_HPP
  11 #define BOOST_HANA_FWD_REMOVE_AT_HPP
  12
  13 #include <boost/hana/config.hpp>
  14 #include <boost/hana/core/when.hpp>
  15
  16 #include <cstddef>
  17
  18
  19 BOOST_HANA_NAMESPACE_BEGIN
  20     //! Remove the element at a given index from a sequence.
  21     //! @ingroup group-Sequence
  22     //!
  23     //! `remove_at` returns a new sequence identical to the original, except
  24     //! that the element at the given index is removed. Specifically,
  25     //! `remove_at([x0, ..., xn-1, xn, xn+1, ..., xm], n)` is a new
  26     //! sequence equivalent to `[x0, ..., xn-1, xn+1, ..., xm]`.
  27     //!
  28     //! @note
  29     //! The behavior is undefined if the index is out of the bounds of the
  30     //! sequence.
  31     //!
  32     //!
  33     //! @param xs
  34     //! A sequence from which an element is to be removed.
  35     //!
  36     //! @param n
  37     //! An non-negative `IntegralConstant` representing the index of the
  38     //! element to be removed from the sequence. The behavior is undefined
  39     //! if that index is not in the bounds of the sequence.
  40     //!
  41     //!
  42     //! Example
  43     //! -------
  44     //! @include example/remove_at.cpp
  45 #ifdef BOOST_HANA_DOXYGEN_INVOKED
  46     constexpr auto remove_at = [](auto&& xs, auto const& n) {
  47         return tag-dispatched;
  48     };
  49 #else
  50     template <typename S, typename = void>
  51     struct remove_at_impl : remove_at_impl<S, when<true>> { };
  52
  53     struct remove_at_t {
  54         template <typename Xs, typename N>
  55         constexpr auto operator()(Xs&& xs, N const& n) const;
  56     };
  57
  58     constexpr remove_at_t remove_at{};
  59 #endif
  60
  61     //! Equivalent to `remove_at`; provided for convenience.
  62     //! @ingroup group-Sequence
  63     //!
  64     //!
  65     //! Example
  66     //! -------
  67     //! @include example/remove_at_c.cpp
  68 #ifdef BOOST_HANA_DOXYGEN_INVOKED
  69     template <std::size_t n>
  70     constexpr auto remove_at_c = [](auto&& xs) {
  71         return hana::remove_at(forwarded(xs), hana::size_c<n>);
  72     };
  73 #else
  74     template <std::size_t n>
  75     struct remove_at_c_t;
  76
  77     template <std::size_t n>
  78     constexpr remove_at_c_t<n> remove_at_c{};
  79 #endif
  80 BOOST_HANA_NAMESPACE_END
  81
  82 #endif // !BOOST_HANA_FWD_REMOVE_AT_HPP