54 lines
1.4 KiB
C++
54 lines
1.4 KiB
C++
|
/*!
|
||
|
|
@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
|