de.dhke.projects.cutil.collections.frozen.FrozenSet.java Source code

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Here is the source code for de.dhke.projects.cutil.collections.frozen.FrozenSet.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.frozen;

import de.dhke.projects.cutil.collections.CollectionUtil;
import de.dhke.projects.cutil.collections.map.CuckooHashMap;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import org.apache.commons.collections15.SetUtils;
import org.apache.commons.collections15.set.MapBackedSet;

/**
 *
 * @author Peter Wullinger <java@dhke.de>
 */
public class FrozenSet<T> implements Set<T> {
    private final Set<T> _baseSet;

    private int _hashValue = 0;

    public FrozenSet(final Collection<? extends T> source) {
        final int capacity = source.size();
        _baseSet = MapBackedSet.decorate(new CuckooHashMap<T, Object>(capacity));
        _baseSet.addAll(source);
    }

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

    @Override
    public boolean isEmpty() {
        return _baseSet.isEmpty();
    }

    @Override
    public boolean contains(Object o) {
        return _baseSet.contains(o);
    }

    @Override
    public Iterator<T> iterator() {
        return FrozenIterator.decorate(_baseSet.iterator());
    }

    @Override
    public Object[] toArray() {
        return _baseSet.toArray();
    }

    @Override
    public <T> T[] toArray(T[] a) {
        return _baseSet.toArray(a);
    }

    @Override
    public boolean add(T e) {
        throw new UnsupportedOperationException("Unable to modify FrozenSet");
    }

    @Override
    public boolean remove(Object o) {
        throw new UnsupportedOperationException("Unable to modify FrozenSet");
    }

    @Override
    public boolean containsAll(Collection<?> c) {
        return _baseSet.containsAll(c);
    }

    @Override
    public boolean addAll(Collection<? extends T> c) {
        throw new UnsupportedOperationException("Unable to modify FrozenSet");
    }

    @Override
    public boolean retainAll(Collection<?> c) {
        throw new UnsupportedOperationException("Unable to modify FrozenSet");
    }

    @Override
    public boolean removeAll(Collection<?> c) {
        throw new UnsupportedOperationException("Unable to modify FrozenSet");
    }

    @Override
    public void clear() {
        throw new UnsupportedOperationException("Unable to modify FrozenSet");
    }

    @Override
    public int hashCode() {
        if (_hashValue == 0)
            _hashValue = SetUtils.hashCodeForSet(_baseSet);
        return _hashValue;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        else if (obj instanceof Collection)
            return SetUtils.isEqualSet(_baseSet, (Collection<?>) obj);
        else
            return false;
    }

    @Override
    public String toString() {
        /* MapBackedSet fails to properly implement toString(). Do it here */
        return CollectionUtil.deepToString(_baseSet);
    }
}