genode/base/include/util/avl_tree.h
2012-01-03 15:35:05 +01:00

204 lines
4.3 KiB
C++

/*
* \brief AVL tree
* \author Norman Feske
* \date 2006-04-12
*/
/*
* Copyright (C) 2006-2012 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__UTIL__AVL_TREE_H_
#define _INCLUDE__UTIL__AVL_TREE_H_
#include <util/misc_math.h>
namespace Genode {
class Avl_node_base
{
protected:
/**
* Internal policy interface
*
* The implementation of this interface is provided by the AVL tree.
*/
struct Policy
{
virtual ~Policy() { }
/**
* Compare two nodes
*
* \retval false if n2 is lower than n1
* \retval true if n2 is higher than or equal to n1
*
* This function must be provided by the derived class.
* It determines the order of nodes inside the avl tree.
*/
virtual bool higher(Avl_node_base *n1, Avl_node_base *n2) const = 0;
/**
* Node recomputation hook
*
* If a node gets rearranged, this function is called.
* It can be used to update avl-tree-position dependent
* meta data.
*/
virtual void recompute(Avl_node_base *) { }
};
Avl_node_base *_child[2]; /* left and right subtrees */
Avl_node_base *_parent; /* parent of subtree */
unsigned char _depth; /* depth of subtree */
public:
typedef bool Side;
enum { LEFT = false, RIGHT = true };
private:
/**
* Determine depth of subtree
*/
inline int _child_depth(Side i) {
return _child[i] ? _child[i]->_depth : 0; }
/**
* Update depth of node
*/
void _recompute_depth(Policy &policy);
/**
* Determine left-right bias of both subtrees
*/
inline Side _bias() {
return (_child_depth(RIGHT) > _child_depth(LEFT)); }
/**
* Insert subtree into specified side of the node
*/
void _adopt(Avl_node_base *node, Side i, Policy &policy);
/**
* Rotate subtree
*
* \param side direction of rotate operation
* \param node subtree to rotate
*
* The local node_* variable names describe node locations for
* the left (default) rotation. For example, node_r_l is the
* left of the right of node.
*/
void _rotate_subtree(Avl_node_base *node, Side side, Policy &policy);
/**
* Rebalance subtree
*
* \param node immediate child that needs balancing
*
* 'this' is parent of the subtree to rebalance
*/
void _rebalance_subtree(Avl_node_base *node, Policy &policy);
public:
/**
* Constructor
*/
Avl_node_base();
/**
* Insert new node into subtree
*/
void insert(Avl_node_base *node, Policy &policy);
/**
* Remove node from tree
*/
void remove(Policy &policy);
};
/**
* AVL node
*
* \param NT type of the class derived from 'Avl_node'
*
* Each object to be stored in the avl tree must be derived from
* 'Avl_node'. The type of the derived class is to be specified as
* template argument to enable 'Avl_node' to call virtual functions
* specific for the derived class.
*/
template <typename NT>
class Avl_node : public Avl_node_base
{
public:
inline NT *child(Side i) const { return static_cast<NT *>(_child[i]); }
/**
* Default policy
*/
void recompute() { }
};
/**
* Root node of the AVL tree
*
* The real nodes are always attached at the left branch of
* this root node.
*/
template <typename NT>
class Avl_tree : Avl_node<NT>
{
private:
/**
* Auto-generated policy class specific for NT
*/
class Policy : public Avl_node_base::Policy
{
bool higher(Avl_node_base *n1, Avl_node_base *n2) const
{
return static_cast<NT *>(n1)->higher(static_cast<NT *>(n2));
}
void recompute(Avl_node_base *node)
{
static_cast<NT *>(node)->recompute();
}
} _policy;
public:
/**
* Insert node into AVL tree
*/
void insert(Avl_node<NT> *node) { Avl_node_base::insert(node, _policy); }
/**
* Remove node from AVL tree
*/
void remove(Avl_node<NT> *node) { node->remove(_policy); }
/**
* Request first node of the tree
*
* \return first node
* \retval NULL if tree is empty
*/
inline NT *first() const { return this->child(Avl_node<NT>::LEFT); }
};
}
#endif /* _INCLUDE__UTIL__AVL_TREE_H_ */