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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___STOP_TOKEN_INTRUSIVE_LIST_VIEW_H
#define _LIBCPP___STOP_TOKEN_INTRUSIVE_LIST_VIEW_H
#include <__assert>
#include <__config>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 20
template <class _Derived>
struct __intrusive_node_base {
_Derived* __next_ = nullptr;
_Derived* __prev_ = nullptr;
};
// This class is a view of underlying double-linked list.
// It does not own the nodes. It provides user-friendly
// operations on the linked list.
template <class _Node>
struct __intrusive_list_view {
_LIBCPP_HIDE_FROM_ABI __intrusive_list_view() = default;
_LIBCPP_HIDE_FROM_ABI __intrusive_list_view(__intrusive_list_view const&) = default;
_LIBCPP_HIDE_FROM_ABI __intrusive_list_view(__intrusive_list_view&&) = default;
_LIBCPP_HIDE_FROM_ABI __intrusive_list_view& operator=(__intrusive_list_view const&) = default;
_LIBCPP_HIDE_FROM_ABI __intrusive_list_view& operator=(__intrusive_list_view&&) = default;
_LIBCPP_HIDE_FROM_ABI ~__intrusive_list_view() = default;
_LIBCPP_HIDE_FROM_ABI bool __empty() const noexcept { return __head_ == nullptr; }
_LIBCPP_HIDE_FROM_ABI void __push_front(_Node* __node) noexcept {
__node->__next_ = __head_;
if (__head_) {
__head_->__prev_ = __node;
}
__head_ = __node;
}
_LIBCPP_HIDE_FROM_ABI _Node* __pop_front() noexcept {
_Node* __front = __head_;
__head_ = __head_->__next_;
if (__head_) {
__head_->__prev_ = nullptr;
}
// OK not to set __front->__next_ = nullptr as __front is not part of the list anymore
return __front;
}
_LIBCPP_HIDE_FROM_ABI void __remove(_Node* __node) noexcept {
if (__node->__prev_) {
// prev exists, set its next to our next to skip __node
__node->__prev_->__next_ = __node->__next_;
if (__node->__next_) {
__node->__next_->__prev_ = __node->__prev_;
}
} else {
_LIBCPP_ASSERT_INTERNAL(__node == __head_, "Node to be removed has no prev node, so it has to be the head");
__pop_front();
}
}
_LIBCPP_HIDE_FROM_ABI bool __is_head(_Node* __node) noexcept { return __node == __head_; }
private:
_Node* __head_ = nullptr;
};
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___STOP_TOKEN_INTRUSIVE_LIST_VIEW_H
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