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 Hu Chunming
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/*!
@file
Forward declares `boost::hana::and_`.
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_AND_HPP
#define BOOST_HANA_FWD_AND_HPP
#include <boost/hana/config.hpp>
#include <boost/hana/core/when.hpp>
namespace boost { namespace hana {
//! Return whether all the arguments are true-valued.
//! @ingroup group-Logical
//!
//! `and_` can be called with one argument or more. When called with
//! two arguments, `and_` uses tag-dispatching to find the right
//! implementation. Otherwise,
//! @code
//! and_(x) == x
//! and_(x, y, ...z) == and_(and_(x, y), z...)
//! @endcode
//!
//!
//! Example
//! -------
//! @include example/and.cpp
#ifdef BOOST_HANA_DOXYGEN_INVOKED
constexpr auto and_ = [](auto&& x, auto&& ...y) -> decltype(auto) {
return tag-dispatched;
};
#else
template <typename L, typename = void>
struct and_impl : and_impl<L, when<true>> { };
struct and_t {
template <typename X, typename Y>
constexpr decltype(auto) operator()(X&& x, Y&& y) const;
template <typename X, typename ...Y>
constexpr decltype(auto) operator()(X&& x, Y&& ...y) const;
};
BOOST_HANA_INLINE_VARIABLE constexpr and_t and_{};
#endif
}} // end namespace boost::hana
#endif // !BOOST_HANA_FWD_AND_HPP
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