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 <__cstddef/ptrdiff_t.h>
  15 #include <__cstddef/size_t.h>
  16 #include <__type_traits/common_type.h>
  17 #include <__type_traits/make_signed.h>
  18
  19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  20 #  pragma GCC system_header
  21 #endif
  22
  23 _LIBCPP_BEGIN_NAMESPACE_STD
  24
  25 #if _LIBCPP_STD_VER >= 17
  26
  27 template <class _Cont>
  28 _LIBCPP_HIDE_FROM_ABI constexpr auto size(const _Cont& __c) noexcept(noexcept(__c.size())) -> decltype(__c.size()) {
  29   return __c.size();
  30 }
  31
  32 template <class _Tp, size_t _Sz>
  33 _LIBCPP_HIDE_FROM_ABI constexpr size_t size(const _Tp (&)[_Sz]) noexcept {
  34   return _Sz;
  35 }
  36
  37 #  if _LIBCPP_STD_VER >= 20
  38 template <class _Cont>
  39 _LIBCPP_HIDE_FROM_ABI constexpr auto
  40 ssize(const _Cont& __c) noexcept(noexcept(static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(
  41     __c.size()))) -> common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>> {
  42   return static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size());
  43 }
  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_HIDE_FROM_ABI constexpr ptrdiff_t ssize(const _Tp (&)[_Sz]) noexcept {
  51   return _Sz;
  52 }
  53 _LIBCPP_DIAGNOSTIC_POP
  54 #  endif
  55
  56 #endif // _LIBCPP_STD_VER >= 17
  57
  58 _LIBCPP_END_NAMESPACE_STD
  59
  60 #endif // _LIBCPP___ITERATOR_SIZE_H