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// -*- 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 <__config>
#include <__iterator/concepts.h>
#include <__iterator/counted_iterator.h>
#include <__iterator/default_sentinel.h>
#include <__iterator/iterator_traits.h>
#include <__ranges/access.h>
#include <__ranges/all.h>
#include <__ranges/concepts.h>
#include <__ranges/enable_borrowed_range.h>
#include <__ranges/size.h>
#include <__ranges/view_interface.h>
#include <__utility/move.h>
#include <concepts>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
#if !defined(_LIBCPP_HAS_NO_CONCEPTS)
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 take_view(_View __base, range_difference_t<_View> __count)
: __base_(_VSTD::move(__base)), __count_(__count) {}
_LIBCPP_HIDE_FROM_ABI
constexpr _View base() const& requires copy_constructible<_View> { return __base_; }
_LIBCPP_HIDE_FROM_ABI
constexpr _View base() && { return _VSTD::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_);
// TODO: use ranges::min here.
return _VSTD::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_);
// TODO: use ranges::min here.
return _VSTD::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_(_VSTD::move(__end)) {}
_LIBCPP_HIDE_FROM_ABI
constexpr __sentinel(__sentinel<!_Const> __s)
requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>>
: __end_(_VSTD::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<_Const>& __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 ranges
#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___RANGES_TAKE_VIEW_H
|
