63e88f80
 Hu Chunming
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/*!
@file
Forward declares `boost::hana::min`.
Copyright Louis Dionne 2013-2022
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_MIN_HPP
#define BOOST_HANA_FWD_MIN_HPP
#include <boost/hana/config.hpp>
#include <boost/hana/core/when.hpp>
namespace boost { namespace hana {
//! Returns the smallest of its arguments according to the `less` ordering.
//! @ingroup group-Orderable
//!
//!
//! @todo
//! We can't specify the signature right now, because the tag of the
//! returned object depends on whether `x < y` or not. If we wanted to be
//! mathematically correct, we should probably ask that `if_(cond, x, y)`
//! returns a common data type of `x` and `y`, and then the behavior
//! of `min` would follow naturally. However, I'm unsure whether this
//! is desirable because that's a big requirement.
//!
//!
//! Example
//! -------
//! @include example/min.cpp
#ifdef BOOST_HANA_DOXYGEN_INVOKED
constexpr auto min = [](auto&& x, auto&& y) -> decltype(auto) {
return tag-dispatched;
};
#else
template <typename T, typename U, typename = void>
struct min_impl : min_impl<T, U, when<true>> { };
struct min_t {
template <typename X, typename Y>
constexpr decltype(auto) operator()(X&& x, Y&& y) const;
};
BOOST_HANA_INLINE_VARIABLE constexpr min_t min{};
#endif
}} // end namespace boost::hana
#endif // !BOOST_HANA_FWD_MIN_HPP
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