mirror of
https://github.com/ecency/ecency-mobile.git
synced 2024-12-23 13:22:02 +03:00
49 lines
1.7 KiB
C++
49 lines
1.7 KiB
C++
|
/*!
|
||
|
@file
|
||
|
Defines a replacement for `std::decay`, which is sometimes too slow at
|
||
|
compile-time.
|
||
|
|
||
|
@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_DETAIL_DECAY_HPP
|
||
|
#define BOOST_HANA_DETAIL_DECAY_HPP
|
||
|
|
||
|
#include <boost/hana/config.hpp>
|
||
|
|
||
|
#include <type_traits>
|
||
|
|
||
|
|
||
|
BOOST_HANA_NAMESPACE_BEGIN namespace detail {
|
||
|
//! @ingroup group-details
|
||
|
//! Equivalent to `std::decay`, except faster.
|
||
|
//!
|
||
|
//! `std::decay` in libc++ is implemented in a suboptimal way. Since
|
||
|
//! this is used literally everywhere by the `make<...>` functions, it
|
||
|
//! is very important to keep this as efficient as possible.
|
||
|
//!
|
||
|
//! @note
|
||
|
//! `std::decay` is still being used in some places in the library.
|
||
|
//! Indeed, this is a peephole optimization and it would not be wise
|
||
|
//! to clutter the code with our own implementation of `std::decay`,
|
||
|
//! except when this actually makes a difference in compile-times.
|
||
|
template <typename T, typename U = typename std::remove_reference<T>::type>
|
||
|
struct decay {
|
||
|
using type = typename std::remove_cv<U>::type;
|
||
|
};
|
||
|
|
||
|
template <typename T, typename U>
|
||
|
struct decay<T, U[]> { using type = U*; };
|
||
|
template <typename T, typename U, std::size_t N>
|
||
|
struct decay<T, U[N]> { using type = U*; };
|
||
|
|
||
|
template <typename T, typename R, typename ...A>
|
||
|
struct decay<T, R(A...)> { using type = R(*)(A...); };
|
||
|
template <typename T, typename R, typename ...A>
|
||
|
struct decay<T, R(A..., ...)> { using type = R(*)(A..., ...); };
|
||
|
} BOOST_HANA_NAMESPACE_END
|
||
|
|
||
|
#endif // !BOOST_HANA_DETAIL_DECAY_HPP
|