54 lines
1.5 KiB
C++
54 lines
1.5 KiB
C++
/*!
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@file
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Forward declares `boost::hana::and_`.
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@copyright Louis Dionne 2013-2016
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
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*/
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#ifndef BOOST_HANA_FWD_AND_HPP
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#define BOOST_HANA_FWD_AND_HPP
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#include <boost/hana/config.hpp>
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#include <boost/hana/core/when.hpp>
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BOOST_HANA_NAMESPACE_BEGIN
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//! Return whether all the arguments are true-valued.
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//! @ingroup group-Logical
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//!
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//! `and_` can be called with one argument or more. When called with
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//! two arguments, `and_` uses tag-dispatching to find the right
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//! implementation. Otherwise,
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//! @code
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//! and_(x) == x
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//! and_(x, y, ...z) == and_(and_(x, y), z...)
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//! @endcode
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//!
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//!
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//! Example
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//! -------
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//! @include example/and.cpp
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#ifdef BOOST_HANA_DOXYGEN_INVOKED
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constexpr auto and_ = [](auto&& x, auto&& ...y) -> decltype(auto) {
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return tag-dispatched;
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};
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#else
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template <typename L, typename = void>
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struct and_impl : and_impl<L, when<true>> { };
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struct and_t {
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template <typename X, typename Y>
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constexpr decltype(auto) operator()(X&& x, Y&& y) const;
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template <typename X, typename ...Y>
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constexpr decltype(auto) operator()(X&& x, Y&& ...y) const;
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};
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constexpr and_t and_{};
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#endif
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BOOST_HANA_NAMESPACE_END
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#endif // !BOOST_HANA_FWD_AND_HPP
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