// -*- 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_FILTER_VIEW_H
#define _LIBCPP___RANGES_FILTER_VIEW_H
#include <__algorithm/ranges_find_if.h>
#include <__assert>
#include <__concepts/constructible.h>
#include <__concepts/copyable.h>
#include <__concepts/derived_from.h>
#include <__concepts/equality_comparable.h>
#include <__config>
#include <__functional/bind_back.h>
#include <__functional/invoke.h>
#include <__functional/reference_wrapper.h>
#include <__iterator/concepts.h>
#include <__iterator/iter_move.h>
#include <__iterator/iter_swap.h>
#include <__iterator/iterator_traits.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/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 >= 20
namespace ranges {
template <input_range _View, indirect_unary_predicate<iterator_t<_View>> _Pred>
requires view<_View> && is_object_v<_Pred>
class _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS filter_view : public view_interface<filter_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) begin() whenever
// the underlying range is at least a forward_range.
static constexpr bool _UseCache = forward_range<_View>;
using _Cache = _If<_UseCache, __non_propagating_cache<iterator_t<_View>>, __empty_cache>;
_LIBCPP_NO_UNIQUE_ADDRESS _Cache __cached_begin_ = _Cache();
class __iterator;
class __sentinel;
public:
_LIBCPP_HIDE_FROM_ABI filter_view()
requires default_initializable<_View> && default_initializable<_Pred>
= default;
_LIBCPP_HIDE_FROM_ABI constexpr _LIBCPP_EXPLICIT_SINCE_CXX23 filter_view(_View __base, _Pred __pred)
: __base_(std::move(__base)), __pred_(in_place, std::move(__pred)) {}
template <class _Vp = _View>
_LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
requires copy_constructible<_Vp>
{
return __base_;
}
_LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
_LIBCPP_HIDE_FROM_ABI constexpr _Pred const& 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 filter_view that does not have a valid predicate.");
if constexpr (_UseCache) {
if (!__cached_begin_.__has_value()) {
__cached_begin_.__emplace(ranges::find_if(__base_, std::ref(*__pred_)));
}
return {*this, *__cached_begin_};
} else {
return {*this, ranges::find_if(__base_, std::ref(*__pred_))};
}
}
_LIBCPP_HIDE_FROM_ABI constexpr auto end() {
if constexpr (common_range<_View>)
return __iterator{*this, ranges::end(__base_)};
else
return __sentinel{*this};
}
};
template <class _Range, class _Pred>
filter_view(_Range&&, _Pred) -> filter_view<views::all_t<_Range>, _Pred>;
template <class _View>
struct __filter_iterator_category {};
template <forward_range _View>
struct __filter_iterator_category<_View> {
using _Cat = typename iterator_traits<iterator_t<_View>>::iterator_category;
using iterator_category =
_If<derived_from<_Cat, bidirectional_iterator_tag>,
bidirectional_iterator_tag,
_If<derived_from<_Cat, forward_iterator_tag>,
forward_iterator_tag,
/* else */ _Cat >>;
};
template <input_range _View, indirect_unary_predicate<iterator_t<_View>> _Pred>
requires view<_View> && is_object_v<_Pred>
class filter_view<_View, _Pred>::__iterator : public __filter_iterator_category<_View> {
public:
_LIBCPP_NO_UNIQUE_ADDRESS iterator_t<_View> __current_ = iterator_t<_View>();
_LIBCPP_NO_UNIQUE_ADDRESS filter_view* __parent_ = nullptr;
using iterator_concept =
_If<bidirectional_range<_View>,
bidirectional_iterator_tag,
_If<forward_range<_View>,
forward_iterator_tag,
/* else */ input_iterator_tag >>;
// using iterator_category = inherited;
using value_type = range_value_t<_View>;
using difference_type = range_difference_t<_View>;
_LIBCPP_HIDE_FROM_ABI __iterator()
requires default_initializable<iterator_t<_View>>
= default;
_LIBCPP_HIDE_FROM_ABI constexpr __iterator(filter_view& __parent, iterator_t<_View> __current)
: __current_(std::move(__current)), __parent_(std::addressof(__parent)) {}
_LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_View> const& base() const& noexcept { return __current_; }
_LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_View> base() && { return std::move(__current_); }
_LIBCPP_HIDE_FROM_ABI constexpr range_reference_t<_View> operator*() const { return *__current_; }
_LIBCPP_HIDE_FROM_ABI constexpr iterator_t<_View> operator->() const
requires __has_arrow<iterator_t<_View>> && copyable<iterator_t<_View>>
{
return __current_;
}
_LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {
__current_ =
ranges::find_if(std::move(++__current_), ranges::end(__parent_->__base_), std::ref(*__parent_->__pred_));
return *this;
}
_LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++*this; }
_LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int)
requires forward_range<_View>
{
auto __tmp = *this;
++*this;
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--()
requires bidirectional_range<_View>
{
do {
--__current_;
} while (!std::invoke(*__parent_->__pred_, *__current_));
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==(__iterator const& __x, __iterator const& __y)
requires equality_comparable<iterator_t<_View>>
{
return __x.__current_ == __y.__current_;
}
_LIBCPP_HIDE_FROM_ABI friend constexpr range_rvalue_reference_t<_View>
iter_move(__iterator const& __it) noexcept(noexcept(ranges::iter_move(__it.__current_))) {
return ranges::iter_move(__it.__current_);
}
_LIBCPP_HIDE_FROM_ABI friend constexpr void
iter_swap(__iterator const& __x,
__iterator const& __y) noexcept(noexcept(ranges::iter_swap(__x.__current_, __y.__current_)))
requires indirectly_swappable<iterator_t<_View>>
{
return ranges::iter_swap(__x.__current_, __y.__current_);
}
};
template <input_range _View, indirect_unary_predicate<iterator_t<_View>> _Pred>
requires view<_View> && is_object_v<_Pred>
class filter_view<_View, _Pred>::__sentinel {
public:
sentinel_t<_View> __end_ = sentinel_t<_View>();
_LIBCPP_HIDE_FROM_ABI __sentinel() = default;
_LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(filter_view& __parent) : __end_(ranges::end(__parent.__base_)) {}
_LIBCPP_HIDE_FROM_ABI constexpr sentinel_t<_View> base() const { return __end_; }
_LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(__iterator const& __x, __sentinel const& __y) {
return __x.__current_ == __y.__end_;
}
};
namespace views {
namespace __filter {
struct __fn {
template <class _Range, class _Pred>
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Pred&& __pred) const
noexcept(noexcept(filter_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred))))
-> decltype(filter_view(std::forward<_Range>(__range), std::forward<_Pred>(__pred))) {
return filter_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 __filter
inline namespace __cpo {
inline constexpr auto filter = __filter::__fn{};
} // namespace __cpo
} // namespace views
} // namespace ranges
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___RANGES_FILTER_VIEW_H
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