de.dhke.projects.cutil.collections.aspect.AspectMapKeySet.java Source code

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Here is the source code for de.dhke.projects.cutil.collections.aspect.AspectMapKeySet.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.aspect;

import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.apache.commons.collections15.keyvalue.DefaultMapEntry;

/**
 *
 * @author Peter Wullinger <java@dhke.de>
 */
public class AspectMapKeySet<K, V, M extends Map<K, V>> implements Set<K> {
    private final AspectMap<K, V, M> _aspectMap;
    private final Set<K> _keySet;

    protected AspectMapKeySet(final AspectMap<K, V, M> aspectMap) {
        _aspectMap = aspectMap;
        _keySet = aspectMap.getDecoratee().keySet();
    }

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

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

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

    @Override
    public Iterator<K> iterator() {
        return new Itr();
    }

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

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

    @Override
    public boolean add(final K e) {
        throw new UnsupportedOperationException("Cannot add to keyset");
    }

    @Override
    public boolean remove(final Object o) {
        boolean wasRemoved = _aspectMap.containsKey(o);
        _aspectMap.remove(o);
        return wasRemoved;
    }

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

    @Override
    public boolean addAll(final Collection<? extends K> c) {
        throw new UnsupportedOperationException("Cannot add to keyset");
    }

    @Override
    public boolean retainAll(final Collection<?> c) {
        return batchRemove(c, true);
    }

    @Override
    public boolean removeAll(final Collection<?> c) {
        return batchRemove(c, false);
    }

    @Override
    public void clear() {
        if (!isEmpty()) {
            CollectionEvent<Map.Entry<K, V>, Map<K, V>> ev = _aspectMap.notifyBeforeCollectionCleared(_aspectMap);
            _keySet.clear();
            _aspectMap.notifyAfterCollectionCleared(ev);
        }
    }

    @Override
    public String toString() {
        return _keySet.toString();
    }

    private boolean batchRemove(final Collection<?> c, final boolean retain) {
        for (K key : _keySet) {
            if (c.contains(key) != retain) {
                Map.Entry<K, V> entry = new DefaultMapEntry<>(key, _aspectMap.get(key));
                _aspectMap.notifyBeforeElementRemoved(_aspectMap, entry);
            }
        }

        boolean wasRemoved = false;
        Iterator<K> iter = _aspectMap.getDecoratee().keySet().iterator();
        while (iter.hasNext()) {
            K key = iter.next();
            if (c.contains(key) != retain) {
                Map.Entry<K, V> entry = new DefaultMapEntry<>(key, _aspectMap.get(key));
                iter.remove();
                wasRemoved = true;
                _aspectMap.notifyAfterElementRemoved(_aspectMap, entry);
            }
        }
        return wasRemoved;
    }

    private class Itr implements Iterator<K> {
        private final Iterator<K> _keyIterator;
        private K _current = null;

        Itr() {
            _keyIterator = _aspectMap.getDecoratee().keySet().iterator();
        }

        @Override
        public boolean hasNext() {
            return _keyIterator.hasNext();
        }

        @Override
        public K next() {
            _current = _keyIterator.next();
            return _current;
        }

        @Override
        public void remove() {
            Map.Entry<K, V> entry = new DefaultMapEntry<>(_current, _aspectMap.get(_current));
            CollectionItemEvent<Entry<K, V>, Map<K, V>> ev = _aspectMap.notifyBeforeElementRemoved(_aspectMap,
                    entry);
            _keyIterator.remove();
            _aspectMap.notifyAfterElementRemoved(ev);
        }
    }
}