haiku/headers/private/kernel/util/DoublyLinkedList.h

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/*
** Copyright 2003, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
** Distributed under the terms of the OpenBeOS License.
*/
#ifndef KERNEL_UTIL_DOUBLY_LINKED_LIST_H
#define KERNEL_UTIL_DOUBLY_LINKED_LIST_H
#include <SupportDefs.h>
#ifdef __cplusplus
/* This header defines a doubly-linked list. It differentiates between a link
* and an item.
* It's the C++ version of <util/list.h> it's very small and efficient, but
* has not been perfectly C++-ified yet.
* The link must be part of the item, it cannot be allocated on demand yet.
*/
namespace DoublyLinked {
class Link {
public:
Link *next;
Link *prev;
};
template<class Item, Link Item::* LinkMember = &Item::fLink> class Iterator;
template<class Item, Link Item::* LinkMember = &Item::fLink>
class List {
public:
//typedef typename Item ValueType;
typedef Iterator<Item, LinkMember> IteratorType;
List()
{
fLink.next = fLink.prev = &fLink;
}
void Add(Item *item)
{
//Link *link = &item->*LinkMember;
(item->*LinkMember).next = &fLink;
(item->*LinkMember).prev = fLink.prev;
fLink.prev->next = &(item->*LinkMember);
fLink.prev = &(item->*LinkMember);
}
void Remove(Item *item)
{
(item->*LinkMember).next->prev = (item->*LinkMember).prev;
(item->*LinkMember).prev->next = (item->*LinkMember).next;
}
Item *RemoveHead()
{
if (IsEmpty())
return NULL;
Item *item = GetItem(fLink.next);
Remove(item);
return item;
}
IteratorType Iterator()
{
return IteratorType(*this);
}
bool IsEmpty()
{
return fLink.next == &fLink;
}
Link *Head()
{
return fLink.next;
}
static inline size_t Offset()
{
return (size_t)&(((Item *)1)->*LinkMember) - 1;
}
static inline Item *GetItem(Link *link)
{
return (Item *)((uint8 *)link - Offset());
}
private:
Link fLink;
};
template<class Item, Link Item::* LinkMember>
class Iterator {
public:
typedef List<Item, LinkMember> ListType;
Iterator() : fCurrent(NULL) {}
Iterator(ListType &list) : fCurrent(list.Head()) {}
Item *Next()
{
if (fCurrent->next == NULL)
return NULL;
Link *current = fCurrent;
fCurrent = fCurrent->next;
return ListType::GetItem(current);
}
private:
Link *fCurrent;
};
} // namespace DoublyLinked
#endif /* __cplusplus */
#endif /* KERNEL_UTIL_DOUBLY_LINKED_LIST_H */