llvm-project/libcxx/include/__ranges/counted.h

95 lines
3.0 KiB
C++

// -*- 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___RANGES_COUNTED_H
#define _LIBCPP___RANGES_COUNTED_H
#include <__config>
#include <__iterator/concepts.h>
#include <__iterator/counted_iterator.h>
#include <__iterator/default_sentinel.h>
#include <__iterator/incrementable_traits.h>
#include <__iterator/iterator_traits.h>
#include <__memory/pointer_traits.h>
#include <__ranges/concepts.h>
#include <__ranges/subrange.h>
#include <__utility/decay_copy.h>
#include <__utility/declval.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <span>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if !defined(_LIBCPP_HAS_NO_RANGES)
namespace ranges::views {
namespace __counted {
template<class _From, class _To>
concept __explicitly_convertible = requires {
_To(_From{});
};
struct __fn {
template<class _Iter, class _Diff>
requires contiguous_iterator<decay_t<_Iter>> &&
__explicitly_convertible<_Diff, iter_difference_t<_Iter>>
_LIBCPP_HIDE_FROM_ABI
constexpr auto operator()(_Iter&& __it, _Diff __c) const
noexcept(noexcept(
span(_VSTD::to_address(__it), static_cast<iter_difference_t<_Iter>>(__c))
))
{
return span(_VSTD::to_address(__it), static_cast<iter_difference_t<_Iter>>(__c));
}
template<class _Iter, class _Diff>
requires random_access_iterator<decay_t<_Iter>> &&
__explicitly_convertible<_Diff, iter_difference_t<_Iter>>
_LIBCPP_HIDE_FROM_ABI
constexpr auto operator()(_Iter&& __it, _Diff __c) const
noexcept(
noexcept(__it + static_cast<iter_difference_t<_Iter>>(__c)) &&
noexcept(ranges::subrange(_VSTD::forward<_Iter>(__it), _VSTD::__decay_copy(__it)))
)
{
auto __last = __it + static_cast<iter_difference_t<_Iter>>(__c);
return ranges::subrange(_VSTD::forward<_Iter>(__it), _VSTD::move(__last));
}
template<class _Iter, class _Diff>
requires __explicitly_convertible<_Diff, iter_difference_t<_Iter>>
_LIBCPP_HIDE_FROM_ABI
constexpr auto operator()(_Iter&& __it, _Diff __c) const
noexcept(noexcept(
ranges::subrange(counted_iterator(_VSTD::forward<_Iter>(__it), __c), default_sentinel)
))
{
return ranges::subrange(counted_iterator(_VSTD::forward<_Iter>(__it), __c), default_sentinel);
}
};
}
inline namespace __cpo {
inline constexpr auto counted = __counted::__fn{};
} // namespace __cpo
} // namespace ranges::views
#endif // !defined(_LIBCPP_HAS_NO_RANGES)
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___RANGES_COUNTED_H