// -*- 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_CHUNK_BY_VIEW_H
#define _LIBCPP___RANGES_CHUNK_BY_VIEW_H
#include <__algorithm/ranges_adjacent_find.h>
#include <__assert>
#include <__concepts/constructible.h>
#include <__config>
#include <__functional/bind_back.h>
#include <__functional/invoke.h>
#include <__iterator/concepts.h>
#include <__iterator/default_sentinel.h>
#include <__iterator/iterator_traits.h>
#include <__iterator/next.h>
#include <__iterator/prev.h>
#include <__memory/addressof.h>
#include <__ranges/access.h>
#include <__ranges/all.h>
#include <__ranges/concepts.h>
#include <__ranges/movable_box.h>
#include <__ranges/non_propagating_cache.h>
#include <__ranges/range_adaptor.h>
#include <__ranges/reverse_view.h>
#include <__ranges/subrange.h>
#include <__ranges/view_interface.h>
#include <__type_traits/conditional.h>
#include <__type_traits/decay.h>
#include <__type_traits/is_nothrow_constructible.h>
#include <__type_traits/is_object.h>
#include <__utility/forward.h>
#include <__utility/in_place.h>
#include <__utility/move.h>
#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 >= 23
namespace ranges {
template <forward_range _View, indirect_binary_predicate<iterator_t<_View>, iterator_t<_View>> _Pred>
requires view<_View> && is_object_v<_Pred>
class _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS chunk_by_view : public view_interface<chunk_by_view<_View, _Pred>> {
_LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
_LIBCPP_NO_UNIQUE_ADDRESS __movable_box<_Pred> __pred_;
// We cache the result of begin() to allow providing an amortized O(1).
using _Cache = __non_propagating_cache<iterator_t<_View>>;
_Cache __cached_begin_;
class __iterator;
_LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_View> __find_next(iterator_t<_View> __current) {
// Note: this duplicates a check in `optional` but provides a better error message.
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
__pred_.__has_value(), "Trying to call __find_next() on a chunk_by_view that does not have a valid predicate.");
auto __reversed_pred = [this]<class _Tp, class _Up>(_Tp&& __x, _Up&& __y) -> bool {
return !std::invoke(*__pred_, std::forward<_Tp>(__x), std::forward<_Up>(__y));
};
return ranges::next(
ranges::adjacent_find(__current, ranges::end(__base_), __reversed_pred), 1, ranges::end(__base_));
}
_LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_View> __find_prev(iterator_t<_View> __current)
requires bidirectional_range<_View>
{
// Attempting to decrement a begin iterator is a no-op (`__find_prev` would return the same argument given to it).
_LIBCPP_ASSERT_PEDANTIC(__current != ranges::begin(__base_), "Trying to call __find_prev() on a begin iterator.");
// Note: this duplicates a check in `optional` but provides a better error message.
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
__pred_.__has_value(), "Trying to call __find_prev() on a chunk_by_view that does not have a valid predicate.");
auto __first = ranges::begin(__base_);
reverse_view __reversed{subrange{__first, __current}};
auto __reversed_pred = [this]<class _Tp, class _Up>(_Tp&& __x, _Up&& __y) -> bool {
return !std::invoke(*__pred_, std::forward<_Up>(__y), std::forward<_Tp>(__x));
};
return ranges::prev(ranges::adjacent_find(__reversed, __reversed_pred).base(), 1, std::move(__first));
}
public:
_LIBCPP_HIDE_FROM_ABI chunk_by_view()
requires default_initializable<_View> && default_initializable<_Pred>
= default;
_LIBCPP_HIDE_FROM_ABI constexpr explicit chunk_by_view(_View __base, _Pred __pred)
: __base_(std::move(__base)), __pred_(in_place, std::move(__pred)) {}
_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 const _Pred& pred() const { return *__pred_; }
_LIBCPP_HIDE_FROM_ABI constexpr __iterator begin() {
// Note: this duplicates a check in `optional` but provides a better error message.
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
__pred_.__has_value(), "Trying to call begin() on a chunk_by_view that does not have a valid predicate.");
auto __first = ranges::begin(__base_);
if (!__cached_begin_.__has_value()) {
__cached_begin_.__emplace(__find_next(__first));
}
return {*this, std::move(__first), *__cached_begin_};
}
_LIBCPP_HIDE_FROM_ABI constexpr auto end() {
if constexpr (common_range<_View>) {
return __iterator{*this, ranges::end(__base_), ranges::end(__base_)};
} else {
return default_sentinel;
}
}
};
template <class _Range, class _Pred>
chunk_by_view(_Range&&, _Pred) -> chunk_by_view<views::all_t<_Range>, _Pred>;
template <forward_range _View, indirect_binary_predicate<iterator_t<_View>, iterator_t<_View>> _Pred>
requires view<_View> && is_object_v<_Pred>
class chunk_by_view<_View, _Pred>::__iterator {
friend chunk_by_view;
chunk_by_view* __parent_ = nullptr;
_LIBCPP_NO_UNIQUE_ADDRESS iterator_t<_View> __current_ = iterator_t<_View>();
_LIBCPP_NO_UNIQUE_ADDRESS iterator_t<_View> __next_ = iterator_t<_View>();
_LIBCPP_HIDE_FROM_ABI constexpr __iterator(
chunk_by_view& __parent, iterator_t<_View> __current, iterator_t<_View> __next)
: __parent_(std::addressof(__parent)), __current_(__current), __next_(__next) {}
public:
using value_type = subrange<iterator_t<_View>>;
using difference_type = range_difference_t<_View>;
using iterator_category = input_iterator_tag;
using iterator_concept = conditional_t<bidirectional_range<_View>, bidirectional_iterator_tag, forward_iterator_tag>;
_LIBCPP_HIDE_FROM_ABI __iterator() = default;
_LIBCPP_HIDE_FROM_ABI constexpr value_type operator*() const {
// If the iterator is at end, this would return an empty range which can be checked by the calling code and doesn't
// necessarily lead to a bad access.
_LIBCPP_ASSERT_PEDANTIC(__current_ != __next_, "Trying to dereference past-the-end chunk_by_view iterator.");
return {__current_, __next_};
}
_LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {
// Attempting to increment an end iterator is a no-op (`__find_next` would return the same argument given to it).
_LIBCPP_ASSERT_PEDANTIC(__current_ != __next_, "Trying to increment past end chunk_by_view iterator.");
__current_ = __next_;
__next_ = __parent_->__find_next(__current_);
return *this;
}
_LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int) {
auto __tmp = *this;
++*this;
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--()
requires bidirectional_range<_View>
{
__next_ = __current_;
__current_ = __parent_->__find_prev(__next_);
return *this;
}
_LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int)
requires bidirectional_range<_View>
{
auto __tmp = *this;
--*this;
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y) {
return __x.__current_ == __y.__current_;
}
_LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, default_sentinel_t) {
return __x.__current_ == __x.__next_;
}
};
namespace views {
namespace __chunk_by {
struct __fn {
template <class _Range, class _Pred>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Pred&& __pred) const
noexcept(noexcept(/**/ chunk_by_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred))))
-> decltype(/*--*/ chunk_by_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred))) {
return /*-------------*/ chunk_by_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred));
}
template <class _Pred>
requires constructible_from<decay_t<_Pred>, _Pred>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Pred&& __pred) const
noexcept(is_nothrow_constructible_v<decay_t<_Pred>, _Pred>) {
return __range_adaptor_closure_t(std::__bind_back(*this, std::forward<_Pred>(__pred)));
}
};
} // namespace __chunk_by
inline namespace __cpo {
inline constexpr auto chunk_by = __chunk_by::__fn{};
} // namespace __cpo
} // namespace views
} // namespace ranges
#endif // _LIBCPP_STD_VER >= 23
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___RANGES_CHUNK_BY_VIEW_H
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