de.dhke.projects.cutil.collections.ExtractorCollection.java Source code

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Here is the source code for de.dhke.projects.cutil.collections.ExtractorCollection.java

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/**
 * (c) 2009-2014 Peter Wullinger
 *
 * $Id$
 *
 * Use, modification and restribution of this file are covered by the
 * terms of the Artistic License 2.0.
 *
 * You should have received a copy of the license terms in a file named
 * "LICENSE" together with this software package.
 *
 * Disclaimer of Warranty: THE PACKAGE IS PROVIDED BY THE COPYRIGHT
 * HOLDER AND CONTRIBUTORS "AS IS' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES. THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
 * A PARTICULAR PURPOSE, OR NON-INFRINGEMENT ARE DISCLAIMED TO THE
 * EXTENT PERMITTED BY YOUR LOCAL LAW. UNLESS REQUIRED BY LAW, NO
 * COPYRIGHT HOLDER OR CONTRIBUTOR WILL BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY OUT
 * OF THE USE OF THE PACKAGE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 **/
package de.dhke.projects.cutil.collections;

import de.dhke.projects.cutil.IDecorator;
import java.util.AbstractCollection;
import java.util.Collection;
import java.util.Iterator;
import org.apache.commons.collections15.Transformer;
import org.apache.commons.collections15.collection.TransformedCollection;

/**
 * Wrapper collection that supports transformed reading from
 * another collection.
 * <p/>
 * Can bee seen as as the "reader" variant of {@link TransformedCollection},
 * which transforms items <em>ADDED</em> to a collection.
 * 
 * @param <I> 
 * @param <O> 
 * 
 * @author Peter Wullinger <java@dhke.de>
 */
public class ExtractorCollection<I, O> extends AbstractCollection<O>
        implements Collection<O>, IDecorator<Collection<? extends I>> {
    private final Collection<? extends I> _baseCollection;
    private final Transformer<I, O> _transformer;

    protected ExtractorCollection(Collection<? extends I> baseCollection, Transformer<I, O> transformer) {
        _baseCollection = baseCollection;
        _transformer = transformer;
    }

    public static <I, O> ExtractorCollection<I, O> decorate(Collection<? extends I> baseCollection,
            Transformer<I, O> transformer) {
        return new ExtractorCollection<>(baseCollection, transformer);
    }

    @Override
    public Iterator<O> iterator() {
        return new ExtractorIterator<>(_baseCollection.iterator(), _transformer);
    }

    @Override
    public int size() {
        return _baseCollection.size();
    }

    @Override
    public Collection<? extends I> getDecoratee() {
        return _baseCollection;
    }
}