__cxx03/__iterator/empty.h

0001 // -*- C++ -*-
0002 //===----------------------------------------------------------------------===//
0003 //
0004 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0005 // See https://llvm.org/LICENSE.txt for license information.
0006 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0007 //
0008 //===----------------------------------------------------------------------===//
0009
0010 #ifndef _LIBCPP___CXX03___ITERATOR_EMPTY_H
0011 #define _LIBCPP___CXX03___ITERATOR_EMPTY_H
0012
0013 #include <__cxx03/__config>
0014 #include <__cxx03/cstddef>
0015 #include <__cxx03/initializer_list>
0016
0017 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0018 #  pragma GCC system_header
0019 #endif
0020
0021 _LIBCPP_BEGIN_NAMESPACE_STD
0022
0023 #if _LIBCPP_STD_VER >= 17
0024
0025 template <class _Cont>
0026 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto
0027 empty(const _Cont& __c) noexcept(noexcept(__c.empty())) -> decltype(__c.empty()) {
0028   return __c.empty();
0029 }
0030
0031 template <class _Tp, size_t _Sz>
0032 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool empty(const _Tp (&)[_Sz]) noexcept {
0033   return false;
0034 }
0035
0036 template <class _Ep>
0037 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool empty(initializer_list<_Ep> __il) noexcept {
0038   return __il.size() == 0;
0039 }
0040
0041 #endif // _LIBCPP_STD_VER >= 17
0042
0043 _LIBCPP_END_NAMESPACE_STD
0044
0045 #endif // _LIBCPP___CXX03___ITERATOR_EMPTY_H