From 8174112d403e07fddc72d574aa02b2412700f5af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Axel=20D=C3=B6rfler?= <axeld@pinc-software.de>
Date: Mon, 13 Oct 2003 01:57:05 +0000
Subject: [PATCH] Almost straight copy of the list.h doubly linked list
 implementation to a C++ one ready for kernel use, but very basic, too. Has
 not been tested yet, expect some bug fixes soon.

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@5001 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 .../private/kernel/util/DoublyLinkedList.h    | 126 ++++++++++++++++++
 1 file changed, 126 insertions(+)
 create mode 100644 headers/private/kernel/util/DoublyLinkedList.h

diff --git a/headers/private/kernel/util/DoublyLinkedList.h b/headers/private/kernel/util/DoublyLinkedList.h
new file mode 100644
index 0000000000..2a3a6b79cb
--- /dev/null
+++ b/headers/private/kernel/util/DoublyLinkedList.h
@@ -0,0 +1,126 @@
+/* 
+** 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 */