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

   1 /*!
   2 @file
   3 Forward declares `boost::hana::div`.
   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_DIV_HPP
  11 #define BOOST_HANA_FWD_DIV_HPP
  12
  13 #include <boost/hana/config.hpp>
  14 #include <boost/hana/core/when.hpp>
  15
  16
  17 namespace boost { namespace hana {
  18     //! Generalized integer division.
  19     //! @ingroup group-EuclideanRing
  20     //!
  21     //!
  22     //! Cross-type version of the method
  23     //! --------------------------------
  24     //! The `div` method is "overloaded" to handle distinct data types
  25     //! with certain properties. Specifically, `div` is defined for
  26     //! _distinct_ data types `A` and `B` such that
  27     //! 1. `A` and `B` share a common data type `C`, as determined by the
  28     //!    `common` metafunction
  29     //! 2. `A`, `B` and `C` are all `EuclideanRing`s when taken individually
  30     //! 3. `to<C> : A -> B` and `to<C> : B -> C` are `Ring`-embeddings, as
  31     //!    determined by the `is_embedding` metafunction.
  32     //!
  33     //! In that case, the `div` method is defined as
  34     //! @code
  35     //!     div(x, y) = div(to<C>(x), to<C>(y))
  36     //! @endcode
  37     //!
  38     //!
  39     //! Example
  40     //! -------
  41     //! @include example/div.cpp
  42 #ifdef BOOST_HANA_DOXYGEN_INVOKED
  43     constexpr auto div = [](auto&& x, auto&& y) -> decltype(auto) {
  44         return tag-dispatched;
  45     };
  46 #else
  47     template <typename T, typename U, typename = void>
  48     struct div_impl : div_impl<T, U, when<true>> { };
  49
  50     struct div_t {
  51         template <typename X, typename Y>
  52         constexpr decltype(auto) operator()(X&& x, Y&& y) const;
  53     };
  54
  55     BOOST_HANA_INLINE_VARIABLE constexpr div_t div{};
  56 #endif
  57 }} // end namespace boost::hana
  58
  59 #endif // !BOOST_HANA_FWD_DIV_HPP