org.hibernate.envers.internal.tools.graph.GraphTopologicalSort Maven / Gradle / Ivy
/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2013, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* 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 Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.envers.internal.tools.graph;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* @author Adam Warski (adam at warski dot org)
*/
public final class GraphTopologicalSort {
private GraphTopologicalSort() {
}
/**
* Sorts a graph topologically.
*
* @param definer Defines a graph (values and representations) to sort.
*
* @return Values of the graph, sorted topologically.
*/
public static List sort(GraphDefiner definer) {
final List values = definer.getValues();
final Map> vertices = new HashMap>();
// Creating a vertex for each representation
for ( V v : values ) {
final R rep = definer.getRepresentation( v );
vertices.put( rep, new Vertex( rep ) );
}
// Connecting neighbourhooding vertices
for ( V v : values ) {
for ( V vn : definer.getNeighbours( v ) ) {
vertices.get( definer.getRepresentation( v ) )
.addNeighbour( vertices.get( definer.getRepresentation( vn ) ) );
}
}
// Sorting the representations
final List sortedReps = new TopologicalSort().sort( vertices.values() );
// Transforming the sorted representations to sorted values
final List sortedValues = new ArrayList( sortedReps.size() );
for ( R rep : sortedReps ) {
sortedValues.add( definer.getValue( rep ) );
}
return sortedValues;
}
}