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/*
* (C) Copyright 2015-2023, by Fabian Späh and Contributors.
*
* JGraphT : a free Java graph-theory library
*
* See the CONTRIBUTORS.md file distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0, or the
* GNU Lesser General Public License v2.1 or later
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html.
*
* SPDX-License-Identifier: EPL-2.0 OR LGPL-2.1-or-later
*/
package org.jgrapht.alg.isomorphism;
import org.jgrapht.*;
import java.util.*;
abstract class VF2MappingIterator
implements Iterator>
{
protected Comparator vertexComparator;
protected Comparator edgeComparator;
protected IsomorphicGraphMapping nextMapping;
protected Boolean hadOneMapping;
protected GraphOrdering ordering1, ordering2;
protected ArrayDeque> stateStack;
public VF2MappingIterator(
GraphOrdering ordering1, GraphOrdering ordering2,
Comparator vertexComparator, Comparator edgeComparator)
{
this.ordering1 = ordering1;
this.ordering2 = ordering2;
this.vertexComparator = vertexComparator;
this.edgeComparator = edgeComparator;
this.stateStack = new ArrayDeque<>();
}
/**
* This function moves over all mappings between graph1 and graph2. It changes the state of the
* whole iterator.
*
* @return null or one matching between graph1 and graph2
*/
protected abstract IsomorphicGraphMapping match();
protected IsomorphicGraphMapping matchAndCheck()
{
IsomorphicGraphMapping rel = match();
if (rel != null) {
hadOneMapping = true;
}
return rel;
}
@Override
public boolean hasNext()
{
return nextMapping != null || (nextMapping = matchAndCheck()) != null;
}
@Override
public IsomorphicGraphMapping next()
{
if (nextMapping != null) {
IsomorphicGraphMapping tmp = nextMapping;
nextMapping = null;
return tmp;
}
IsomorphicGraphMapping rel = matchAndCheck();
if (rel == null) {
throw new NoSuchElementException();
}
return rel;
}
@Override
public void remove()
{
throw new UnsupportedOperationException();
}
}