pfr/detail/rvalue_t.hpp

0001 // Copyright (c) 2016-2025 Antony Polukhin
0002 //
0003 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0004 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0005
0006 #ifndef BOOST_PFR_DETAIL_RVALUE_T_HPP
0007 #define BOOST_PFR_DETAIL_RVALUE_T_HPP
0008 #pragma once
0009
0010 #ifdef BOOST_PFR_HAS_STD_MODULE
0011 import std;
0012 #else
0013 #include <type_traits>
0014 #include <utility>      // std::enable_if_t
0015 #endif
0016
0017 // This header provides aliases rvalue_t and lvalue_t.
0018 //
0019 // Usage: template <class T> void foo(rvalue<T> rvalue);
0020 //
0021 // Those are useful for
0022 //  * better type safety - you can validate at compile time that only rvalue reference is passed into the function
0023 //  * documentation and readability - rvalue_t<T> is much better than T&&+SFINAE
0024
0025 namespace boost { namespace pfr { namespace detail {
0026
0027 /// Binds to rvalues only, no copying allowed.
0028 template <class T
0029 #ifdef BOOST_PFR_DETAIL_STRICT_RVALUE_TESTING
0030     , class = std::enable_if_t<std::is_rvalue_reference<T&&>::value>
0031 #endif
0032 >
0033 using rvalue_t = T&&;
0034
0035 /// Binds to mutable lvalues only
0036
0037 }}} // namespace boost::pfr::detail
0038
0039 #endif // BOOST_PFR_DETAIL_RVALUE_T_HPP