path: root/src/datastructures/linkedlists/sentinel-template

/* -*- java -*- */
/**
 * Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * 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 Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
{
    /**
     * Node for the list
     */
    public class Node
    {
	/**
	 * Constructor
	 * 
	 * @param  value  The value to store in the list
	 */
	public Node(T value)
	{
	    this.value = value;
	}
	
	
	
	/**
	 * The value stored in the list by this node
	 */
	public T value;
	
	/**
	 * The next node in the list
	 */
	public Node next = null;
	
£>if (( with_prev )); then
	/**
	 * The previous node in the list
	 */
	public Node previous = null;
£>fi
	
    }
    
    
    
    /**
     * The sentinel node in the list
     */
    public Node edge;
    
    
    
    /**
     * Initialiser
     */
    {
	this.edge = new Node(null);
	this.edge.next = this.edge;
£>if (( with_prev )); then
	this.edge.previous = this.edge;
£>fi
    }
    
    
    
    /**
     * Insert a value in the beginning of the list
     * 
     * @param   value  The value to insert
     * @return         The node that has been created and inserted
     */
    public Node insertBeginning(T value)
    {
	return insertAfter(value, this.edge);
    }
    
    /**
     * Remove the node at the beginning of the list
     * 
     * @return  The node that has been removed
     */
    public Node removeBeginning()
    {
	return removeAfter(this.edge);
    }
    
    /**
     * Insert a value after a specified, reference, node
     * 
     * @param   value        The value to insert
     * @param   predecessor  The reference node
     * @return               The node that has been created and inserted
     */
    public Node insertAfter(T value, Node predecessor)
    {
	Node node = new Node(value);
	node.next = predecessor.next;
	predecessor.next = node;
£>if (( with_prev )); then
	node.previous = predecessor;
	node.next.previous = node;
£>fi
	return node;
    }
    
    /**
     * Remove the node after a specified, reference, node
     * 
     * @param   predecessor  The reference node
     * @return               The node that has been removed
     */
    public Node removeAfter(Node predecessor)
    {
	Node node = predecessor.next;
	predecessor.next = node.next;
£>if (( with_prev )); then
	predecessor.next.previous = predecessor;
£>fi
	return node;
    }
    
£>if (( with_prev )); then
    /**
     * Insert a value before a specified, reference, node
     * 
     * @param   value      The value to insert
     * @param   successor  The reference node
     * @return             The node that has been created and inserted
     */
    public Node insertBefore(T value, Node successor)
    {
	Node node = new Node(value);
	node.previous = successor.previous;
	successor.previous = node;
	node.next = successor;
	node.previous.next = node;
	return node;
    }
    
    /**
     * Remove the node before a specified, reference, node
     * 
     * @param   successor  The reference node
     * @return             The node that has been removed
     */
    public Node removeBefore(Node successor)
    {
	Node node = successor.previous;
	successor.previous = node.previous;
	successor.previous.next = successor;
	return node;
    }
    
    /**
     * Remove the node from the list
     * 
     * @param  node  The node to remove
     */
    public void remove(Node node)
    {
	node.previous.next = node.next;
	node.next.previous = node.previous;
    }
    
    /**
     * Insert a value in the end of the list
     * 
     * @param   value  The value to insert
     * @return         The node that has been created and inserted
     */
    public Node insertEnd(T value)
    {
	return insertBefore(value, this.edge);
    }
    
    /**
     * Remove the node at the end of the list
     * 
     * @return  The node that has been removed
     */
    public Node removeEnd()
    {
	return removeBefore(this.edge);
    }
£>fi
    
}