/**
* 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;
/**
* In order to make the solving of shortest path problems as general as
* possible, the algorithms accept objects handling all relevant tasks regarding
* costs of paths. This allows the user to represent the costs in any possible
* way, and to calculate them in any way. The usual case is numbers that we just
* add together, but what if we have for example factors we would like to
* multiply instead? This is handled by this system, which works as follows. A
* CostEvaluator is used to get the cost for a single relationship. These costs
* are then added through a CostAccumulator. Costs for alternative paths are
* compared with a common java.util.Comparator.
*
* @author Patrik Larsson
* @param <T> The data type the edge weights are represented by.
*/
public interface CostAccumulator<T>
{
/**
* This is the accumulating method. This should return the results of
* "adding" two path costs with each other.
*
* @param c1 One of the costs.
* @param c2 The other cost.
* @return The resulting cost.
*/
T addCosts( T c1, T c2 );
}