llvm-project/libcxx/include/__iterator/size.h

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___ITERATOR_SIZE_H
#define _LIBCPP___ITERATOR_SIZE_H

#include <__config>
#include <__cstddef/ptrdiff_t.h>
#include <__cstddef/size_t.h>
#include <__type_traits/common_type.h>
#include <__type_traits/make_signed.h>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER >= 17

template <class _Cont>
_LIBCPP_HIDE_FROM_ABI constexpr auto size(const _Cont& __c) noexcept(noexcept(__c.size())) -> decltype(__c.size()) {
  return __c.size();
}

template <class _Tp, size_t _Sz>
_LIBCPP_HIDE_FROM_ABI constexpr size_t size(const _Tp (&)[_Sz]) noexcept {
  return _Sz;
}

#  if _LIBCPP_STD_VER >= 20
template <class _Cont>
_LIBCPP_HIDE_FROM_ABI constexpr auto
ssize(const _Cont& __c) noexcept(noexcept(static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(
    __c.size()))) -> common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>> {
  return static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(__c.size())>>>(__c.size());
}

// GCC complains about the implicit conversion from ptrdiff_t to size_t in
// the array bound.
_LIBCPP_DIAGNOSTIC_PUSH
_LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wsign-conversion")
template <class _Tp, ptrdiff_t _Sz>
_LIBCPP_HIDE_FROM_ABI constexpr ptrdiff_t ssize(const _Tp (&)[_Sz]) noexcept {
  return _Sz;
}
_LIBCPP_DIAGNOSTIC_POP
#  endif

#endif // _LIBCPP_STD_VER >= 17

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___ITERATOR_SIZE_H