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.BinaryPredicate;
020import org.apache.commons.functor.Predicate;
021import org.apache.commons.lang3.Validate;
022
023/**
024 * Adapts a
025 * {@link Predicate Predicate}
026 * to the
027 * {@link BinaryPredicate BinaryPredicate} interface
028 * by ignoring the first binary argument.
029 *
030 * @param <L> the left argument type.
031 * @param <R> the right argument type.
032 * @version $Revision: 1537906 $ $Date: 2013-11-01 12:47:33 +0100 (Fr, 01 Nov 2013) $
033 */
034public final class IgnoreLeftPredicate<L, R> implements BinaryPredicate<L, R> {
035    /** The {@link Predicate Predicate} I'm wrapping. */
036    private final Predicate<? super R> predicate;
037
038    /**
039     * Create a new IgnoreLeftPredicate.
040     * @param predicate the right predicate
041     */
042    public IgnoreLeftPredicate(Predicate<? super R> predicate) {
043        this.predicate = Validate.notNull(predicate, "Predicate argument was null");
044    }
045
046    /**
047     * {@inheritDoc}
048     */
049    public boolean test(L left, R right) {
050        return predicate.test(right);
051    }
052
053    /**
054     * {@inheritDoc}
055     */
056    @Override
057    public boolean equals(Object obj) {
058        if (obj == this) {
059            return true;
060        }
061        if (!(obj instanceof IgnoreLeftPredicate<?, ?>)) {
062            return false;
063        }
064        IgnoreLeftPredicate<?, ?> that = (IgnoreLeftPredicate<?, ?>) obj;
065        return this.predicate.equals(that.predicate);
066    }
067
068    /**
069     * {@inheritDoc}
070     */
071    @Override
072    public int hashCode() {
073        int hash = "IgnoreLeftPredicate".hashCode();
074        hash ^= predicate.hashCode();
075        return hash;
076    }
077
078    /**
079     * {@inheritDoc}
080     */
081    @Override
082    public String toString() {
083        return "IgnoreLeftPredicate<" + predicate + ">";
084    }
085
086    /**
087     * Adapt a Predicate to an IgnoreLeftPredicate.
088     * @param <L> left type
089     * @param <R> right type
090     * @param predicate to adapt
091     * @return IgnoreLeftPredicate<L, R>
092     */
093    public static <L, R> IgnoreLeftPredicate<L, R> adapt(Predicate<? super R> predicate) {
094        return null == predicate ? null : new IgnoreLeftPredicate<L, R>(predicate);
095    }
096
097}