// -*- 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_TAKE_VIEW_H
#define _LIBCPP___RANGES_TAKE_VIEW_H
#include <__algorithm/min.h>
#include <__algorithm/ranges_min.h>
#include <__assert>
#include <__concepts/constructible.h>
#include <__concepts/convertible_to.h>
#include <__config>
#include <__functional/bind_back.h>
#include <__fwd/span.h>
#include <__fwd/string_view.h>
#include <__iterator/concepts.h>
#include <__iterator/counted_iterator.h>
#include <__iterator/default_sentinel.h>
#include <__iterator/distance.h>
#include <__iterator/iterator_traits.h>
#include <__ranges/access.h>
#include <__ranges/all.h>
#include <__ranges/concepts.h>
#include <__ranges/empty_view.h>
#include <__ranges/enable_borrowed_range.h>
#include <__ranges/iota_view.h>
#include <__ranges/range_adaptor.h>
#include <__ranges/repeat_view.h>
#include <__ranges/size.h>
#include <__ranges/subrange.h>
#include <__ranges/view_interface.h>
#include <__type_traits/decay.h>
#include <__type_traits/is_nothrow_constructible.h>
#include <__type_traits/maybe_const.h>
#include <__type_traits/remove_cvref.h>
#include <__utility/auto_cast.h>
#include <__utility/forward.h>
#include <__utility/move.h>
#include <cstddef>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 20
namespace ranges {
template <view _View>
class take_view : public view_interface<take_view<_View>> {
_LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
range_difference_t<_View> __count_ = 0;
template <bool>
class __sentinel;
public:
_LIBCPP_HIDE_FROM_ABI take_view()
requires default_initializable<_View>
= default;
_LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23
take_view(_View __base, range_difference_t<_View> __count)
: __base_(std::move(__base)), __count_(__count) {
_LIBCPP_ASSERT_UNCATEGORIZED(__count >= 0, "count has to be greater than or equal to zero");
}
_LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
requires copy_constructible<_View>
{
return __base_;
}
_LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
_LIBCPP_HIDE_FROM_ABI constexpr auto begin()
requires(!__simple_view<_View>)
{
if constexpr (sized_range<_View>) {
if constexpr (random_access_range<_View>) {
return ranges::begin(__base_);
} else {
using _DifferenceT = range_difference_t<_View>;
auto __size = size();
return counted_iterator(ranges::begin(__base_), static_cast<_DifferenceT>(__size));
}
} else {
return counted_iterator(ranges::begin(__base_), __count_);
}
}
_LIBCPP_HIDE_FROM_ABI constexpr auto begin() const
requires range<const _View>
{
if constexpr (sized_range<const _View>) {
if constexpr (random_access_range<const _View>) {
return ranges::begin(__base_);
} else {
using _DifferenceT = range_difference_t<const _View>;
auto __size = size();
return counted_iterator(ranges::begin(__base_), static_cast<_DifferenceT>(__size));
}
} else {
return counted_iterator(ranges::begin(__base_), __count_);
}
}
_LIBCPP_HIDE_FROM_ABI constexpr auto end()
requires(!__simple_view<_View>)
{
if constexpr (sized_range<_View>) {
if constexpr (random_access_range<_View>) {
return ranges::begin(__base_) + size();
} else {
return default_sentinel;
}
} else {
return __sentinel<false>{ranges::end(__base_)};
}
}
_LIBCPP_HIDE_FROM_ABI constexpr auto end() const
requires range<const _View>
{
if constexpr (sized_range<const _View>) {
if constexpr (random_access_range<const _View>) {
return ranges::begin(__base_) + size();
} else {
return default_sentinel;
}
} else {
return __sentinel<true>{ranges::end(__base_)};
}
}
_LIBCPP_HIDE_FROM_ABI constexpr auto size()
requires sized_range<_View>
{
auto __n = ranges::size(__base_);
return ranges::min(__n, static_cast<decltype(__n)>(__count_));
}
_LIBCPP_HIDE_FROM_ABI constexpr auto size() const
requires sized_range<const _View>
{
auto __n = ranges::size(__base_);
return ranges::min(__n, static_cast<decltype(__n)>(__count_));
}
};
template <view _View>
template <bool _Const>
class take_view<_View>::__sentinel {
using _Base = __maybe_const<_Const, _View>;
template <bool _OtherConst>
using _Iter = counted_iterator<iterator_t<__maybe_const<_OtherConst, _View>>>;
_LIBCPP_NO_UNIQUE_ADDRESS sentinel_t<_Base> __end_ = sentinel_t<_Base>();
template <bool>
friend class take_view<_View>::__sentinel;
public:
_LIBCPP_HIDE_FROM_ABI __sentinel() = default;
_LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(sentinel_t<_Base> __end) : __end_(std::move(__end)) {}
_LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __s)
requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>>
: __end_(std::move(__s.__end_)) {}
_LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_Base> base() const { return __end_; }
_LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const _Iter<_Const>& __lhs, const __sentinel& __rhs) {
return __lhs.count() == 0 || __lhs.base() == __rhs.__end_;
}
template <bool _OtherConst = !_Const>
requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
_LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const _Iter<_OtherConst>& __lhs, const __sentinel& __rhs) {
return __lhs.count() == 0 || __lhs.base() == __rhs.__end_;
}
};
template <class _Range>
take_view(_Range&&, range_difference_t<_Range>) -> take_view<views::all_t<_Range>>;
template <class _Tp>
inline constexpr bool enable_borrowed_range<take_view<_Tp>> = enable_borrowed_range<_Tp>;
namespace views {
namespace __take {
template <class _Tp>
inline constexpr bool __is_empty_view = false;
template <class _Tp>
inline constexpr bool __is_empty_view<empty_view<_Tp>> = true;
template <class _Tp>
inline constexpr bool __is_passthrough_specialization = false;
template <class _Tp, size_t _Extent>
inline constexpr bool __is_passthrough_specialization<span<_Tp, _Extent>> = true;
template <class _CharT, class _Traits>
inline constexpr bool __is_passthrough_specialization<basic_string_view<_CharT, _Traits>> = true;
template <class _Iter, class _Sent, subrange_kind _Kind>
inline constexpr bool __is_passthrough_specialization<subrange<_Iter, _Sent, _Kind>> = true;
template <class _Tp>
inline constexpr bool __is_iota_specialization = false;
template <class _Np, class _Bound>
inline constexpr bool __is_iota_specialization<iota_view<_Np, _Bound>> = true;
template <class _Tp>
struct __passthrough_type;
template <class _Tp, size_t _Extent>
struct __passthrough_type<span<_Tp, _Extent>> {
using type = span<_Tp>;
};
template <class _CharT, class _Traits>
struct __passthrough_type<basic_string_view<_CharT, _Traits>> {
using type = basic_string_view<_CharT, _Traits>;
};
template <class _Iter, class _Sent, subrange_kind _Kind>
requires requires { typename subrange<_Iter>; }
struct __passthrough_type<subrange<_Iter, _Sent, _Kind>> {
using type = subrange<_Iter>;
};
template <class _Tp>
using __passthrough_type_t = typename __passthrough_type<_Tp>::type;
struct __fn {
// [range.take.overview]: the `empty_view` case.
template <class _Range, convertible_to<range_difference_t<_Range>> _Np>
requires __is_empty_view<remove_cvref_t<_Range>>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Np&&) const
noexcept(noexcept(_LIBCPP_AUTO_CAST(std::forward<_Range>(__range))))
-> decltype(_LIBCPP_AUTO_CAST(std::forward<_Range>(__range))) {
return _LIBCPP_AUTO_CAST(std::forward<_Range>(__range));
}
// [range.take.overview]: the `span | basic_string_view | subrange` case.
template <class _Range,
convertible_to<range_difference_t<_Range>> _Np,
class _RawRange = remove_cvref_t<_Range>,
class _Dist = range_difference_t<_Range>>
requires(!__is_empty_view<_RawRange> && random_access_range<_RawRange> && sized_range<_RawRange> &&
__is_passthrough_specialization<_RawRange>)
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto
operator()(_Range&& __rng, _Np&& __n) const noexcept(noexcept(__passthrough_type_t<_RawRange>(
ranges::begin(__rng), ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n)))))
-> decltype(__passthrough_type_t<_RawRange>(
// Note: deliberately not forwarding `__rng` to guard against double moves.
ranges::begin(__rng),
ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n)))) {
return __passthrough_type_t<_RawRange>(
ranges::begin(__rng), ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n)));
}
// [range.take.overview]: the `iota_view` case.
// clang-format off
template <class _Range,
convertible_to<range_difference_t<_Range>> _Np,
class _RawRange = remove_cvref_t<_Range>,
class _Dist = range_difference_t<_Range>>
requires (!__is_empty_view<_RawRange> &&
random_access_range<_RawRange> &&
sized_range<_RawRange> &&
__is_iota_specialization<_RawRange>)
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI
constexpr auto operator()(_Range&& __rng, _Np&& __n) const
noexcept(noexcept(ranges::iota_view(
*ranges::begin(__rng),
*(ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n)))
)))
-> decltype( ranges::iota_view(
// Note: deliberately not forwarding `__rng` to guard against double moves.
*ranges::begin(__rng),
*(ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n)))
))
{ return ranges::iota_view(
*ranges::begin(__rng),
*(ranges::begin(__rng) + std::min<_Dist>(ranges::distance(__rng), std::forward<_Np>(__n)))
); }
#if _LIBCPP_STD_VER >= 23
// [range.take.overview]: the `repeat_view` "_RawRange models sized_range" case.
template <class _Range,
convertible_to<range_difference_t<_Range>> _Np,
class _RawRange = remove_cvref_t<_Range>,
class _Dist = range_difference_t<_Range>>
requires(__is_repeat_specialization<_RawRange> && sized_range<_RawRange>)
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Np&& __n) const
noexcept(noexcept(views::repeat(*__range.__value_, std::min<_Dist>(ranges::distance(__range), std::forward<_Np>(__n)))))
-> decltype( views::repeat(*__range.__value_, std::min<_Dist>(ranges::distance(__range), std::forward<_Np>(__n))))
{ return views::repeat(*__range.__value_, std::min<_Dist>(ranges::distance(__range), std::forward<_Np>(__n))); }
// [range.take.overview]: the `repeat_view` "otherwise" case.
template <class _Range,
convertible_to<range_difference_t<_Range>> _Np,
class _RawRange = remove_cvref_t<_Range>,
class _Dist = range_difference_t<_Range>>
requires(__is_repeat_specialization<_RawRange> && !sized_range<_RawRange>)
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Np&& __n) const
noexcept(noexcept(views::repeat(*__range.__value_, static_cast<_Dist>(__n))))
-> decltype( views::repeat(*__range.__value_, static_cast<_Dist>(__n)))
{ return views::repeat(*__range.__value_, static_cast<_Dist>(__n)); }
#endif
// clang-format on
// [range.take.overview]: the "otherwise" case.
template <class _Range, convertible_to<range_difference_t<_Range>> _Np, class _RawRange = remove_cvref_t<_Range>>
// Note: without specifically excluding the other cases, GCC sees this overload as ambiguous with the other
// overloads.
requires(!(__is_empty_view<_RawRange> ||
# if _LIBCPP_STD_VER >= 23
__is_repeat_specialization<_RawRange> ||
# endif
(__is_iota_specialization<_RawRange> && sized_range<_RawRange> && random_access_range<_RawRange>) ||
(__is_passthrough_specialization<_RawRange> && sized_range<_RawRange> &&
random_access_range<_RawRange>)))
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Np&& __n) const
noexcept(noexcept(take_view(std::forward<_Range>(__range), std::forward<_Np>(__n))))
-> decltype(take_view(std::forward<_Range>(__range), std::forward<_Np>(__n))) {
return take_view(std::forward<_Range>(__range), std::forward<_Np>(__n));
}
template <class _Np>
requires constructible_from<decay_t<_Np>, _Np>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Np&& __n) const
noexcept(is_nothrow_constructible_v<decay_t<_Np>, _Np>) {
return __range_adaptor_closure_t(std::__bind_back(*this, std::forward<_Np>(__n)));
}
};
} // namespace __take
inline namespace __cpo {
inline constexpr auto take = __take::__fn{};
} // namespace __cpo
} // namespace views
} // namespace ranges
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___RANGES_TAKE_VIEW_H
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