filebot/source/net/sourceforge/tuned/TreeIterator.java

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package net.sourceforge.tuned;
import java.util.Arrays;
import java.util.Iterator;
import java.util.LinkedList;
public abstract class TreeIterator<T> implements Iterator<T> {
private final LinkedList<Iterator<T>> recursionStack = new LinkedList<Iterator<T>>();
public TreeIterator(T... root) {
recursionStack.push(Arrays.asList(root).iterator());
}
protected abstract Iterator<T> children(T node);
@Override
public boolean hasNext() {
return currentIterator().hasNext();
}
@Override
public T next() {
T node = currentIterator().next();
Iterator<T> children = children(node);
if (children != null && children.hasNext()) {
// step into next recursion level
recursionStack.push(children);
}
return node;
}
private Iterator<T> currentIterator() {
Iterator<T> iterator = recursionStack.peek();
if (iterator.hasNext() || recursionStack.size() <= 1)
return iterator;
// step back one recursion level
recursionStack.pop();
return currentIterator();
}
@Override
public void remove() {
// can't just use remove() on current iterator, because
// we may have stepped into the next recursion level
throw new UnsupportedOperationException();
}
}