org.apache.cayenne.ashwood.graph.DepthFirstStampSearch Maven / Gradle / Ivy
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/* ====================================================================
*
* Copyright(c) 2003, Andriy Shapochka
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
*
* 2. Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials
* provided with the distribution.
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* 3. Neither the name of the ASHWOOD nor the
* names of its contributors may be used to endorse or
* promote products derived from this software without
* specific prior written permission.
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* ====================================================================
*
* This software consists of voluntary contributions made by
* individuals on behalf of the ASHWOOD Project and was originally
* created by Andriy Shapochka.
*
*/
package org.apache.cayenne.ashwood.graph;
/**
* @since 3.1
*/
public class DepthFirstStampSearch extends DepthFirstSearch {
public static final int UNDEFINED_STAMP = -1;
public static final int GROW_DEPTH_STAMP = 0;
public static final int GROW_BREADTH_STAMP = 1;
public static final int SHRINK_STAMP = 2;
public static final int LEAF_STAMP = 3;
private int stamp = UNDEFINED_STAMP;
public DepthFirstStampSearch(DigraphIteration factory, E firstVertex) {
super(factory, firstVertex);
}
public int getStamp() {
return stamp;
}
@Override
public E next() {
ArcIterator i = (ArcIterator) stack.peek();
E origin = i.getOrigin();
E dst = i.getDestination();
if (dst == null) {
if (i.hasNext()) {
i.next();
dst = i.getDestination();
}
else {
stack.pop();
// shrink
stamp = LEAF_STAMP;
return origin;
}
}
if (seen.add(dst)) {
stack.push(factory.outgoingIterator(dst));
// grow depth
stamp = GROW_DEPTH_STAMP;
if (i.hasNext())
i.next();
}
else {
if (i.hasNext()) {
i.next();
// grow breadth
stamp = GROW_BREADTH_STAMP;
}
else {
stack.pop();
// shrink
stamp = SHRINK_STAMP;
}
}
return origin;
}
}