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'databene commons' is an open source Java library by Volker Bergmann.
It provides extensions to the Java core library by utility classes, abstract concepts
and concrete implementations.
/*
* Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
* All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.databene.commons.iterator;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.Stack;
/**
* Allows linear iteration over nested {@link Set}s using a plain {@link Iterator}.
* Created: 04.08.2013 07:58:05
* @param the type to iterate
* @since 0.5.24
* @author Volker Bergmann
*/
public class RecursiveMapValueIterator implements Iterator {
private Stack> iterators;
private E next;
private boolean hasNext;
public RecursiveMapValueIterator(Map root) {
this.iterators = new Stack>();
this.iterators.push(root.values().iterator());
forward();
}
@Override
public boolean hasNext() {
return hasNext;
}
@Override
public E next() {
E result = next;
forward();
return result;
}
@Override
public void remove() {
iterators.peek().remove();
}
@SuppressWarnings("unchecked")
private void forward() {
Iterator iterator = iterators.peek();
if (iterator.hasNext()) {
Object candidate = iterator.next();
if (candidate instanceof Map) {
iterators.push(((Map) candidate).values().iterator());
forward();
} else {
hasNext = true;
next = (E) candidate;
}
} else if (iterators.size() > 1) {
iterators.pop();
forward();
} else {
this.hasNext = false;
this.next = null;
}
}
}