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package de.lmu.ifi.dbs.elki.utilities.iterator;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2012
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.util.Iterator;
/**
* This interface can convert an {@link Iterable} to an {@link Iterator} or the
* other way round. Note that {@link Iterator} to {@link Iterable} is for
* single-shot use only. This allows for using an Iterator in for:
*
* <blockquote><pre>{@code
* for (Type var : new IterableIterator<Type>(iterator)) {
* // ...
* }
* }</pre></blockquote>
*
* @apiviz.stereotype decorator
* @apiviz.uses Iterable
* @apiviz.uses Iterator
*
* @author Erich Schubert
* @param <T> object type
*/
public final class IterableIteratorAdapter<T> implements IterableIterator<T> {
/**
* Parent Iterable
*/
Iterable<T> parent = null;
/**
* Parent Iterator
*/
Iterator<T> iter = null;
/**
* Constructor from an Iterable (preferred).
*
* @param parent Iterable parent
*/
public IterableIteratorAdapter(Iterable<T> parent) {
this.parent = parent;
assert (parent != null);
}
/**
* Constructor from an Iterator.
*
* If possible, wrap an Iterable object.
*
* @param iter Iterator
*/
public IterableIteratorAdapter(Iterator<T> iter) {
this.iter = iter;
assert (iter != null);
}
@Override
public Iterator<T> iterator() {
if(parent == null) {
return this;
}
return parent.iterator();
}
@Override
public boolean hasNext() {
if(iter == null) {
iter = parent.iterator();
}
return iter.hasNext();
}
@Override
public T next() {
if(iter == null) {
iter = parent.iterator();
}
return iter.next();
}
@Override
public void remove() {
if(iter == null) {
iter = parent.iterator();
}
iter.remove();
}
}
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