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- /*!
- @file
- Forward declares `boost::hana::greater`.
- @copyright Louis Dionne 2013-2017
- Distributed under the Boost Software License, Version 1.0.
- (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
- */
- #ifndef BOOST_HANA_FWD_GREATER_HPP
- #define BOOST_HANA_FWD_GREATER_HPP
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/when.hpp>
- #include <boost/hana/detail/nested_than_fwd.hpp>
- BOOST_HANA_NAMESPACE_BEGIN
- //! Returns a `Logical` representing whether `x` is greater than `y`.
- //! @ingroup group-Orderable
- //!
- //!
- //! Signature
- //! ---------
- //! Given a Logical `Bool` and two Orderables `A` and `B` with a common
- //! embedding, the signature is
- //! @f$ \mathrm{greater} : A \times B \to Bool @f$.
- //!
- //! @param x, y
- //! Two objects to compare.
- //!
- //!
- //! Example
- //! -------
- //! @include example/greater.cpp
- #ifdef BOOST_HANA_DOXYGEN_INVOKED
- constexpr auto greater = [](auto&& x, auto&& y) -> decltype(auto) {
- return tag-dispatched;
- };
- #else
- template <typename T, typename U, typename = void>
- struct greater_impl : greater_impl<T, U, when<true>> { };
- struct greater_t : detail::nested_than<greater_t> {
- template <typename X, typename Y>
- constexpr decltype(auto) operator()(X&& x, Y&& y) const;
- };
- constexpr greater_t greater{};
- #endif
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_FWD_GREATER_HPP
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