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1 | /*! |
2 | @file | |
3 | Forward declares `boost::hana::less`. | |
4 | ||
b32b8144 | 5 | @copyright Louis Dionne 2013-2017 |
7c673cae FG |
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_LESS_HPP | |
11 | #define BOOST_HANA_FWD_LESS_HPP | |
12 | ||
13 | #include <boost/hana/config.hpp> | |
14 | #include <boost/hana/core/when.hpp> | |
15 | #include <boost/hana/detail/nested_than_fwd.hpp> | |
16 | ||
17 | ||
18 | BOOST_HANA_NAMESPACE_BEGIN | |
19 | //! Returns a `Logical` representing whether `x` is less than `y`. | |
20 | //! @ingroup group-Orderable | |
21 | //! | |
22 | //! | |
23 | //! Signature | |
24 | //! --------- | |
25 | //! Given a Logical `Bool` and two Orderables `A` and `B` with a common | |
26 | //! embedding, the signature is | |
27 | //! @f$ \mathrm{less} : A \times B \to Bool @f$. | |
28 | //! | |
29 | //! @param x, y | |
30 | //! Two objects to compare. | |
31 | //! | |
32 | //! | |
33 | //! Example | |
34 | //! ------- | |
35 | //! @include example/less.cpp | |
36 | #ifdef BOOST_HANA_DOXYGEN_INVOKED | |
37 | constexpr auto less = [](auto&& x, auto&& y) { | |
38 | return tag-dispatched; | |
39 | }; | |
40 | #else | |
41 | template <typename T, typename U, typename = void> | |
42 | struct less_impl : less_impl<T, U, when<true>> { }; | |
43 | ||
44 | struct less_t : detail::nested_than<less_t> { | |
45 | template <typename X, typename Y> | |
46 | constexpr auto operator()(X&& x, Y&& y) const; | |
47 | }; | |
48 | ||
49 | constexpr less_t less{}; | |
50 | #endif | |
51 | BOOST_HANA_NAMESPACE_END | |
52 | ||
53 | #endif // !BOOST_HANA_FWD_LESS_HPP |