Smack/smack-core/src/main/java/org/jivesoftware/smack/filter/NotFilter.java

/**
 *
 * Copyright 2003-2007 Jive Software.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.jivesoftware.smack.filter;

import org.jivesoftware.smack.packet.Stanza;
import org.jivesoftware.smack.util.Objects;

/**
 * Implements the logical NOT operation on a stanza(/packet) filter. In other words, packets
 * pass this filter if they do not pass the supplied filter.
 *
 * @author Matt Tucker
 */
public class NotFilter implements StanzaFilter {

    private final StanzaFilter filter;

    /**
     * Creates a NOT filter using the specified filter.
     *
     * @param filter the filter.
     */
    public NotFilter(StanzaFilter filter) {
        this.filter = Objects.requireNonNull(filter, "Parameter must not be null.");
    }

    @Override
    public boolean accept(Stanza packet) {
        return !filter.accept(packet);
    }
}