1 // -*- C++ -*-
2 //===----------------------------------------------------------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #ifndef _LIBCPP___ITERATOR_SIZE_H
11 #define _LIBCPP___ITERATOR_SIZE_H
12 
13 #include <__config>
14 #include <__type_traits/common_type.h>
15 #include <__type_traits/make_signed.h>
16 #include <cstddef>
17 
18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19 #  pragma GCC system_header
20 #endif
21 
22 _LIBCPP_BEGIN_NAMESPACE_STD
23 
24 #if _LIBCPP_STD_VER >= 17
25 
26 template <class _Cont>
27 _LIBCPP_INLINE_VISIBILITY
28 constexpr auto size(const _Cont& __c)
29 _NOEXCEPT_(noexcept(__c.size()))
30 -> decltype        (__c.size())
31 { return            __c.size(); }
32 
33 template <class _Tp, size_t _Sz>
34 _LIBCPP_INLINE_VISIBILITY
35 constexpr size_t size(const _Tp (&)[_Sz]) noexcept { return _Sz; }
36 
37 #if _LIBCPP_STD_VER >= 20
38 template <class _Cont>
39 _LIBCPP_INLINE_VISIBILITY
40 constexpr auto ssize(const _Cont& __c)
41 _NOEXCEPT_(noexcept(static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size())))
42 ->                              common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>
43 { return            static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size()); }
44 
45 // GCC complains about the implicit conversion from ptrdiff_t to size_t in
46 // the array bound.
47 _LIBCPP_DIAGNOSTIC_PUSH
48 _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wsign-conversion")
49 template <class _Tp, ptrdiff_t _Sz>
50 _LIBCPP_INLINE_VISIBILITY
51 constexpr ptrdiff_t ssize(const _Tp (&)[_Sz]) noexcept { return _Sz; }
52 _LIBCPP_DIAGNOSTIC_POP
53 #endif
54 
55 #endif // _LIBCPP_STD_VER >= 17
56 
57 _LIBCPP_END_NAMESPACE_STD
58 
59 #endif // _LIBCPP___ITERATOR_SIZE_H
60