/**
* Copyright (c) 2002-2010 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j 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/>.
*/
package org.neo4j.graphalgo.impl.shortestpath;
import org.neo4j.graphdb.Node;
/**
* Abstraction of the priority queue used by Dijkstra in order to make (testing
* of) alternative implementations easier.
* @param <CostType>
* The datatype the path weigths are represented by.
*/
public interface DijkstraPriorityQueue<CostType>
{
/**
* Used to insert a new value into the queue.
* @param node
* @param value
*/
public void insertValue( Node node, CostType value );
/**
* Used to update a value in the queue (or insert it).
* @param node
* @param newValue
*/
public void decreaseValue( Node node, CostType newValue );
/**
* Retrieve and remove the node with the most optimal value.
*/
public Node extractMin();
/**
* Retrieve without removing the node with the most optimal value.
*/
public Node peek();
/**
* @return True if the queue is empty.
*/
public boolean isEmpty();
}