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.adapter;
018    
019    import java.io.Serializable;
020    
021    import org.apache.commons.functor.Function;
022    import org.apache.commons.functor.Procedure;
023    
024    /**
025     * Adapts a {@link Function Function}
026     * to the {@link Procedure Procedure}
027     * interface by ignoring the value returned
028     * by the function.
029     * <p/>
030     * Note that although this class implements
031     * {@link Serializable}, a given instance will
032     * only be truly <code>Serializable</code> if the
033     * underlying function is.  Attempts to serialize
034     * an instance whose delegate is not
035     * <code>Serializable</code> will result in an exception.
036     *
037     * @version $Revision: 1156778 $ $Date: 2011-08-11 21:50:51 +0200 (Thu, 11 Aug 2011) $
038     * @author Rodney Waldhoff
039     */
040    public final class FunctionProcedure implements Procedure, Serializable {
041        /**
042         * serialVersionUID declaration.
043         */
044        private static final long serialVersionUID = -7300031015086684901L;
045        /** The {@link Function Function} I'm wrapping. */
046        private final Function<?> function;
047    
048        /**
049         * Create an {@link Procedure Procedure} wrapping
050         * the given {@link Function Function}.
051         * @param function the {@link Function Function} to wrap
052         */
053        public FunctionProcedure(Function<?> function) {
054            if (function == null) {
055                throw new IllegalArgumentException("Function argument was null");
056            }
057            this.function = function;
058        }
059    
060        /**
061         * {@inheritDoc}
062         * {@link Function#evaluate Evaluate} my function,
063         * but ignore its returned value.
064         */
065        public void run() {
066            function.evaluate();
067        }
068    
069        /**
070         * {@inheritDoc}
071         */
072        public boolean equals(Object that) {
073            return that == this || (that instanceof FunctionProcedure && equals((FunctionProcedure) that));
074        }
075    
076        /**
077         * Learn whether another FunctionProcedure is equal to this.
078         * @param that FunctionProcedure to test
079         * @return boolean
080         */
081        public boolean equals(FunctionProcedure that) {
082            return null != that && (null == function ? null == that.function : function.equals(that.function));
083        }
084    
085        /**
086         * {@inheritDoc}
087         */
088        public int hashCode() {
089            int hash = "FunctionProcedure".hashCode();
090            if (null != function) {
091                hash ^= function.hashCode();
092            }
093            return hash;
094        }
095    
096        /**
097         * {@inheritDoc}
098         */
099        public String toString() {
100            return "FunctionProcedure<" + function + ">";
101        }
102    
103        /**
104         * Adapt the given, possibly-<code>null</code>,
105         * {@link Function Function} to the
106         * {@link Procedure Procedure} interface.
107         * When the given <code>Function</code> is <code>null</code>,
108         * returns <code>null</code>.
109         *
110         * @param function the possibly-<code>null</code>
111         *        {@link Function Function} to adapt
112         * @return a {@link Procedure Procedure} wrapping the given
113         *         {@link Function Function}, or <code>null</code>
114         *         if the given <code>Function</code> is <code>null</code>
115         */
116        public static FunctionProcedure adapt(Function<?> function) {
117            return null == function ? null : new FunctionProcedure(function);
118        }
119    
120    }