From 9a962e1c512ffc00bcfce105e9dbdabd9abcdd86 Mon Sep 17 00:00:00 2001
From: Attila Molnar <attilamolnar@hush.com>
Date: Fri, 24 Jan 2014 12:37:43 +0100
Subject: [PATCH] Add intrusive list template

---
 include/intrusive_list.h | 162 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 162 insertions(+)
 create mode 100644 include/intrusive_list.h

diff --git a/include/intrusive_list.h b/include/intrusive_list.h
new file mode 100644
index 000000000..399dc33e8
--- /dev/null
+++ b/include/intrusive_list.h
@@ -0,0 +1,162 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *   Copyright (C) 2013-2014 Attila Molnar <attilamolnar@hush.com>
+ *
+ * This file is part of InspIRCd.  InspIRCd is free software: you can
+ * redistribute it and/or modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+#pragma once
+
+#include <iterator>
+
+struct intrusive_list_def_tag { };
+
+template <typename T, typename Tag = intrusive_list_def_tag> class intrusive_list;
+
+template <typename T, typename Tag = intrusive_list_def_tag>
+struct intrusive_list_node
+{
+	T* ptr_next;
+	T* ptr_prev;
+
+	void unlink()
+	{
+		if (ptr_next)
+			ptr_next->intrusive_list_node<T, Tag>::ptr_prev = this->ptr_prev;
+		if (ptr_prev)
+			ptr_prev->intrusive_list_node<T, Tag>::ptr_next = this->ptr_next;
+		ptr_next = ptr_prev = NULL;
+	}
+
+ public:
+	intrusive_list_node()
+		: ptr_next(NULL)
+		, ptr_prev(NULL)
+	{
+	}
+
+	friend class intrusive_list<T, Tag>;
+};
+
+template <typename T, typename Tag>
+class intrusive_list
+{
+ public:
+	class iterator : public std::iterator<std::bidirectional_iterator_tag, T*>
+	{
+		T* curr;
+
+	 public:
+		iterator(T* i = NULL)
+			: curr(i)
+		{
+		}
+
+		iterator& operator++()
+		{
+			curr = curr->intrusive_list_node<T, Tag>::ptr_next;
+			return *this;
+		}
+
+		iterator operator++(int)
+		{
+			iterator ret(*this);
+			operator++();
+			return ret;
+		}
+
+		void operator--()
+		{
+			curr = curr->intrusive_list_node<T, Tag>::ptr_prev;
+			return *this;
+		}
+
+		iterator operator--(int)
+		{
+			iterator ret(*this);
+			operator--();
+			return ret;
+		}
+
+		bool operator==(const iterator& other) const { return (curr == other.curr); }
+		bool operator!=(const iterator& other) const { return (curr != other.curr); }
+		T* operator*() const { return curr; }
+	};
+
+	typedef iterator const_iterator;
+
+	intrusive_list()
+		: listhead(NULL)
+		, listsize(0)
+	{
+	}
+
+	bool empty() const
+	{
+		return (size() == 0);
+	}
+
+	size_t size() const
+	{
+		return listsize;
+	}
+
+	iterator begin() const
+	{
+		return iterator(listhead);
+	}
+
+	iterator end() const
+	{
+		return iterator();
+	}
+
+	void pop_front()
+	{
+		erase(listhead);
+	}
+
+	T* front() const
+	{
+		return listhead;
+	}
+
+	void push_front(T* x)
+	{
+		if (listsize++)
+		{
+			x->intrusive_list_node<T, Tag>::ptr_next = listhead;
+			listhead->intrusive_list_node<T, Tag>::ptr_prev = x;
+		}
+		listhead = x;
+	}
+
+	void erase(const iterator& it)
+	{
+		erase(*it);
+	}
+
+	void erase(T* x)
+	{
+		if (listhead == x)
+			listhead = x->intrusive_list_node<T, Tag>::ptr_next;
+		x->intrusive_list_node<T, Tag>::unlink();
+		listsize--;
+	}
+
+ private:
+	T* listhead;
+	size_t listsize;
+};
-- 
2.39.5