libcxx/include/__iterator/size.h

   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