ceph/src/boost/boost/hana/fwd/accessors.hpp

   1 /*!
   2 @file
   3 Forward declares `boost::hana::accessors`.
   4
   5 @copyright Louis Dionne 2013-2017
   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_ACCESSORS_HPP
  11 #define BOOST_HANA_FWD_ACCESSORS_HPP
  12
  13 #include <boost/hana/config.hpp>
  14 #include <boost/hana/core/when.hpp>
  15
  16
  17 BOOST_HANA_NAMESPACE_BEGIN
  18     //! Returns a `Sequence` of pairs representing the accessors of the
  19     //! data structure.
  20     //! @ingroup group-Struct
  21     //!
  22     //! Given a `Struct` `S`, `accessors<S>()` is a `Sequence` of `Product`s
  23     //! where the first element of each pair is the "name" of a member of
  24     //! the `Struct`, and the second element of each pair is a function that
  25     //! can be used to access that member when given an object of the proper
  26     //! data type. As described in the global documentation for `Struct`, the
  27     //! accessor functions in this sequence must be move-independent.
  28     //!
  29     //!
  30     //! Example
  31     //! -------
  32     //! @include example/accessors.cpp
  33 #ifdef BOOST_HANA_DOXYGEN_INVOKED
  34     template <typename S>
  35     constexpr auto accessors = []() {
  36         return tag-dispatched;
  37     };
  38 #else
  39     template <typename S, typename = void>
  40     struct accessors_impl : accessors_impl<S, when<true>> { };
  41
  42     template <typename S>
  43     struct accessors_t;
  44
  45     template <typename S>
  46     constexpr accessors_t<S> accessors{};
  47 #endif
  48 BOOST_HANA_NAMESPACE_END
  49
  50 #endif // !BOOST_HANA_FWD_ACCESSORS_HPP