org.jgrapht.alg.AbstractPathElement Maven / Gradle / Ivy
/* ==========================================
* JGraphT : a free Java graph-theory library
* ==========================================
*
* Project Info: http://jgrapht.sourceforge.net/
* Project Creator: Barak Naveh (http://sourceforge.net/users/barak_naveh)
*
* (C) Copyright 2003-2007, by Barak Naveh and Contributors.
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
*/
/* -------------------------
* AbstractPathElement.java
* -------------------------
* (C) Copyright 2006-2007, by France Telecom
*
* Original Author: Guillaume Boulmier and Contributors.
* Contributor(s): John V. Sichi
*
* $Id: AbstractPathElement.java 586 2008-01-27 23:30:50Z perfecthash $
*
* Changes
* -------
* 05-Jan-2006 : Initial revision (GB);
* 14-Jan-2006 : Added support for generics (JVS);
*
*/
package org.jgrapht.alg;
import java.util.*;
import org.jgrapht.*;
/**
* A new path is created from a path concatenated to an edge. It's like a linked
* list.
* The empty path is composed only of one vertex.
* In this case the path has no previous path element.
* .
*
* NOTE jvs 1-Jan-2008: This is an internal data structure for use in
* algorithms. For returning paths to callers, use the public {@link GraphPath}
* interface instead.
*
* @author Guillaume Boulmier
* @since July 5, 2007
*/
abstract class AbstractPathElement
{
//~ Instance fields --------------------------------------------------------
/**
* Number of hops of the path.
*/
protected int nHops;
/**
* Edge reaching the target vertex of the path.
*/
protected E prevEdge;
/**
* Previous path element.
*/
protected AbstractPathElement prevPathElement;
/**
* Target vertex.
*/
private V vertex;
//~ Constructors -----------------------------------------------------------
/**
* Creates a path element by concatenation of an edge to a path element.
*
* @param pathElement
* @param edge edge reaching the end vertex of the path element created.
*/
protected AbstractPathElement(
Graph graph,
AbstractPathElement pathElement,
E edge)
{
this.vertex =
Graphs.getOppositeVertex(
graph,
edge,
pathElement.getVertex());
this.prevEdge = edge;
this.prevPathElement = pathElement;
this.nHops = pathElement.getHopCount() + 1;
}
/**
* Copy constructor.
*
* @param original source to copy from
*/
protected AbstractPathElement(AbstractPathElement original)
{
this.nHops = original.nHops;
this.prevEdge = original.prevEdge;
this.prevPathElement = original.prevPathElement;
this.vertex = original.vertex;
}
/**
* Creates an empty path element.
*
* @param vertex end vertex of the path element.
*/
protected AbstractPathElement(V vertex)
{
this.vertex = vertex;
this.prevEdge = null;
this.prevPathElement = null;
this.nHops = 0;
}
//~ Methods ----------------------------------------------------------------
/**
* Returns the path as a list of edges.
*
* @return list of Edge.
*/
public List createEdgeListPath()
{
List path = new ArrayList();
AbstractPathElement pathElement = this;
// while start vertex is not reached.
while (pathElement.getPrevEdge() != null) {
path.add(pathElement.getPrevEdge());
pathElement = pathElement.getPrevPathElement();
}
Collections.reverse(path);
return path;
}
/**
* Returns the number of hops (or number of edges) of the path.
*
* @return .
*/
public int getHopCount()
{
return this.nHops;
}
/**
* Returns the edge reaching the target vertex of the path.
*
* @return null if the path is empty.
*/
public E getPrevEdge()
{
return this.prevEdge;
}
/**
* Returns the previous path element.
*
* @return null is the path is empty.
*/
public AbstractPathElement getPrevPathElement()
{
return this.prevPathElement;
}
/**
* Returns the target vertex of the path.
*
* @return .
*/
public V getVertex()
{
return this.vertex;
}
}
// End AbstractPathElement.java