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 BOOST_HANA_NAMESPACE_BEGIN 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 constexpr div_t div{}; 56 #endif 57 BOOST_HANA_NAMESPACE_END 58 59 #endif // !BOOST_HANA_FWD_DIV_HPP 60