v1/__concepts/boolean_testable.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___CONCEPTS_BOOLEAN_TESTABLE_H
0010 #define _LIBCPP___CONCEPTS_BOOLEAN_TESTABLE_H
0011
0012 #include <__concepts/convertible_to.h>
0013 #include <__config>
0014 #include <__utility/forward.h>
0015
0016 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0017 #  pragma GCC system_header
0018 #endif
0019
0020 _LIBCPP_BEGIN_NAMESPACE_STD
0021
0022 #if _LIBCPP_STD_VER >= 20
0023
0024 // [concepts.booleantestable]
0025
0026 template <class _Tp>
0027 concept __boolean_testable_impl = convertible_to<_Tp, bool>;
0028
0029 template <class _Tp>
0030 concept __boolean_testable = __boolean_testable_impl<_Tp> && requires(_Tp&& __t) {
0031   { !std::forward<_Tp>(__t) } -> __boolean_testable_impl;
0032 };
0033
0034 #endif // _LIBCPP_STD_VER >= 20
0035
0036 _LIBCPP_END_NAMESPACE_STD
0037
0038 #endif // _LIBCPP___CONCEPTS_BOOLEAN_TESTABLE_H