ceph/src/boost/boost/hof/unpack_sequence.hpp

   1 /*=============================================================================
   2     Copyright (c) 2016 Paul Fultz II
   3     unpack_sequence.hpp
   4     Distributed under the Boost Software License, Version 1.0. (See accompanying
   5     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 ==============================================================================*/
   7
   8 #ifndef BOOST_HOF_GUARD_UNPACK_SEQUENCE_HPP
   9 #define BOOST_HOF_GUARD_UNPACK_SEQUENCE_HPP
  10
  11 /// unpack_sequence
  12 /// ===============
  13 ///
  14 /// How to unpack a sequence can be defined by specializing `unpack_sequence`.
  15 /// By default, `std::tuple` is already specialized. To implement this, one
  16 /// needs to provide a static `apply` function which will unpack the sequence
  17 /// to the parameters of the function.
  18 ///
  19 /// Synopsis
  20 /// --------
  21 ///
  22 ///     template<class Sequence, class=void>
  23 ///     struct unpack_sequence;
  24 ///
  25 /// Example
  26 /// -------
  27 ///
  28 ///     #include <boost/hof.hpp>
  29 ///     #include <cassert>
  30 ///
  31 ///     struct my_sequence
  32 ///     {
  33 ///         int x;
  34 ///         int y;
  35 ///     };
  36 ///
  37 ///     namespace boost { namespace hof {
  38 ///         template<>
  39 ///         struct unpack_sequence<my_sequence>
  40 ///         {
  41 ///             template<class F, class Sequence>
  42 ///             constexpr static auto apply(F&& f, Sequence&& s) BOOST_HOF_RETURNS
  43 ///             (
  44 ///                 f(s.x, s.y)
  45 ///             );
  46 ///         };
  47 ///     }} // namespace boost::hof
  48 ///
  49 ///     int main() {
  50 ///     }
  51 ///
  52 /// See Also
  53 /// --------
  54 ///
  55 /// * [unpack](unpack)
  56 /// * [is_unpackable](is_unpackable)
  57 ///
  58
  59 #include <boost/hof/config.hpp>
  60
  61 namespace boost { namespace hof {
  62
  63 template<class Sequence, class=void>
  64 struct unpack_sequence
  65 {
  66     typedef void not_unpackable;
  67 };
  68
  69 }} // namespace boost::hof
  70
  71 #endif