001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.functor.generator;
018    
019    import org.apache.commons.functor.UnaryPredicate;
020    import org.apache.commons.functor.UnaryProcedure;
021    import org.apache.commons.functor.core.composite.ConditionalUnaryProcedure;
022    
023    /**
024     * Generator that filters another Generator by only passing through those elements
025     * that are matched by a specified UnaryPredicate.
026     *
027     * @version $Revision: 1156795 $ $Date: 2011-08-11 22:08:30 +0200 (Thu, 11 Aug 2011) $
028     */
029    public class FilteredGenerator<E> extends BaseGenerator<E> {
030        private final UnaryPredicate<? super E> pred;
031    
032        /**
033         * Create a new FilteredGenerator.
034         * @param wrapped Generator to wrap
035         * @param pred filtering UnaryPredicate
036         */
037        public FilteredGenerator(Generator<? extends E> wrapped, UnaryPredicate<? super E> pred) {
038            super(wrapped);
039            if (wrapped == null) {
040                throw new IllegalArgumentException("Generator argument was null");
041            }
042            if (pred == null) {
043                throw new IllegalArgumentException("UnaryPredicate argument was null");
044            }
045            this.pred = pred;
046        }
047    
048        /**
049         * {@inheritDoc}
050         */
051        public void run(UnaryProcedure<? super E> proc) {
052            getWrappedGenerator().run(new ConditionalUnaryProcedure<E>(pred, proc));
053        }
054    
055        /**
056         * {@inheritDoc}
057         */
058        @SuppressWarnings("unchecked")
059        @Override
060        protected Generator<? extends E> getWrappedGenerator() {
061            return (Generator<? extends E>) super.getWrappedGenerator();
062        }
063    
064        /**
065         * {@inheritDoc}
066         */
067        public boolean equals(Object obj) {
068            if (obj == this) {
069                return true;
070            }
071            if (!(obj instanceof FilteredGenerator<?>)) {
072                return false;
073            }
074            FilteredGenerator<?> other = (FilteredGenerator<?>) obj;
075            return other.getWrappedGenerator().equals(getWrappedGenerator()) && other.pred.equals(pred);
076        }
077    
078        /**
079         * {@inheritDoc}
080         */
081        public int hashCode() {
082            int result = "FilteredGenerator".hashCode();
083            result <<= 2;
084            Generator<?> gen = getWrappedGenerator();
085            result ^= gen == null ? 0 : gen.hashCode();
086            result <<= 2;
087            result ^= pred == null ? 0 : pred.hashCode();
088            return result;
089        }
090    }