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 */
017package org.apache.commons.functor.adapter;
018
019import org.apache.commons.functor.BinaryFunction;
020import org.apache.commons.functor.BinaryPredicate;
021
022/**
023 * Adapts a
024 * {@link BinaryPredicate BinaryPredicate}
025 * to the
026 * {@link BinaryFunction BinaryFunction} interface.
027 *
028 * @param <L> the left argument type.
029 * @param <R> the right argument type.
030 * @version $Revision: 1537906 $ $Date: 2013-11-01 12:47:33 +0100 (Fr, 01 Nov 2013) $
031 */
032public final class BinaryPredicateBinaryFunction<L, R> implements BinaryFunction<L, R, Boolean> {
033    /** The {@link BinaryPredicate BinaryPredicate} I'm wrapping. */
034    private final BinaryPredicate<? super L, ? super R> predicate;
035
036    /**
037     * Create a new BinaryPredicateBinaryFunction.
038     * @param predicate to adapt
039     */
040    public BinaryPredicateBinaryFunction(BinaryPredicate<? super L, ? super R> predicate) {
041        this.predicate = predicate;
042    }
043
044    /**
045     * {@inheritDoc}
046     * Returns <code>Boolean.TRUE</code> (<code>Boolean.FALSE</code>)
047     * when the {@link BinaryPredicate#test test} method of my underlying
048     * predicate returns <code>true</code> (<code>false</code>).
049     *
050     * @return a non-<code>null</code> <code>Boolean</code> instance
051     */
052    public Boolean evaluate(L left, R right) {
053        return predicate.test(left, right) ? Boolean.TRUE : Boolean.FALSE;
054    }
055
056    /**
057     * {@inheritDoc}
058     */
059    @Override
060    public boolean equals(Object obj) {
061        if (obj == this) {
062            return true;
063        }
064        if (!(obj instanceof BinaryPredicateBinaryFunction<?, ?>)) {
065            return false;
066        }
067        BinaryPredicateBinaryFunction<?, ?> that = (BinaryPredicateBinaryFunction<?, ?>) obj;
068        return this.predicate.equals(that.predicate);
069    }
070
071    /**
072     * {@inheritDoc}
073     */
074    @Override
075    public int hashCode() {
076        int hash = "BinaryPredicateBinaryFunction".hashCode();
077        hash ^= predicate.hashCode();
078        return hash;
079    }
080
081    /**
082     * {@inheritDoc}
083     */
084    @Override
085    public String toString() {
086        return "BinaryPredicateBinaryFunction<" + predicate + ">";
087    }
088
089    /**
090     * Adapt the given, possibly-<code>null</code>,
091     * {@link BinaryPredicate BinaryPredicate} to the
092     * {@link BinaryFunction BinaryFunction} interface.
093     * When the given <code>BinaryPredicate</code> is <code>null</code>,
094     * returns <code>null</code>.
095     *
096     * @param <L> left type
097     * @param <R> right type
098     * @param predicate the possibly-<code>null</code>
099     *        {@link BinaryPredicate BinaryPredicate} to adapt
100     * @return a <code>BinaryPredicateBinaryFunction</code> wrapping the given
101     *         {@link BinaryPredicate BinaryPredicate}, or <code>null</code>
102     *         if the given <code>BinaryPredicate</code> is <code>null</code>
103     */
104    public static <L, R> BinaryPredicateBinaryFunction<L, R> adapt(BinaryPredicate<? super L, ? super R> predicate) {
105        return null == predicate ? null : new BinaryPredicateBinaryFunction<L, R>(predicate);
106    }
107
108}