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/*!
@file
Forward declares `boost::hana::or_`.
@copyright Louis Dionne 2013-2016
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_OR_HPP
#define BOOST_HANA_FWD_OR_HPP
#include <boost/hana/config.hpp>
#include <boost/hana/core/when.hpp>
BOOST_HANA_NAMESPACE_BEGIN
//! Return whether any of the arguments is true-valued.
//! @ingroup group-Logical
//!
//! `or_` can be called with one argument or more. When called with
//! two arguments, `or_` uses tag-dispatching to find the right
//! implementation. Otherwise,
//! @code
//! or_(x) == x
//! or_(x, y, ...z) == or_(or_(x, y), z...)
//! @endcode
//!
//!
//! Example
//! -------
//! @include example/or.cpp
#ifdef BOOST_HANA_DOXYGEN_INVOKED
constexpr auto or_ = [](auto&& x, auto&& ...y) -> decltype(auto) {
return tag-dispatched;
};
#else
template <typename L, typename = void>
struct or_impl : or_impl<L, when<true>> { };
struct or_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;
};
constexpr or_t or_{};
#endif
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_FWD_OR_HPP
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