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.collections4.functors;
018
019import java.io.Serializable;
020
021import org.apache.commons.collections4.Equator;
022import org.apache.commons.collections4.Predicate;
023
024/**
025 * Predicate implementation that returns true if the input is the same object
026 * as the one stored in this predicate by equals.
027 *
028 * @since 3.0
029 */
030public final class EqualPredicate<T> implements Predicate<T>, Serializable {
031
032    /** Serial version UID */
033    private static final long serialVersionUID = 5633766978029907089L;
034
035    /**
036     * Factory to create the predicate.
037     *
038     * @param <T> the type that the predicate queries
039     * @param object  the object to compare to
040     * @return the predicate
041     */
042    public static <T> Predicate<T> equalPredicate(final T object) {
043        if (object == null) {
044            return NullPredicate.nullPredicate();
045        }
046        return new EqualPredicate<>(object);
047    }
048
049    /**
050     * Factory to create the identity predicate.
051     *
052     * @param <T> the type that the predicate queries
053     * @param object  the object to compare to
054     * @param equator  the equator to use for comparison
055     * @return the predicate
056     * @since 4.0
057     */
058    public static <T> Predicate<T> equalPredicate(final T object, final Equator<T> equator) {
059        if (object == null) {
060            return NullPredicate.nullPredicate();
061        }
062        return new EqualPredicate<>(object, equator);
063    }
064
065    /** The value to compare to */
066    private final T iValue;
067
068    /** The equator to use for comparison */
069    private final Equator<T> equator;
070
071    /**
072     * Constructor that performs no validation.
073     * Use {@code equalPredicate} if you want that.
074     *
075     * @param object  the object to compare to
076     */
077    public EqualPredicate(final T object) {
078        // do not use the DefaultEquator to keep backwards compatibility
079        // the DefaultEquator returns also true if the two object references are equal
080        this(object, null);
081    }
082
083    /**
084     * Constructor that performs no validation.
085     * Use {@code equalPredicate} if you want that.
086     *
087     * @param object  the object to compare to
088     * @param equator  the equator to use for comparison
089     * @since 4.0
090     */
091    public EqualPredicate(final T object, final Equator<T> equator) {
092        iValue = object;
093        this.equator = equator;
094    }
095
096    /**
097     * Evaluates the predicate returning true if the input equals the stored value.
098     *
099     * @param object  the input object
100     * @return true if input object equals stored value
101     */
102    @Override
103    public boolean evaluate(final T object) {
104        if (equator != null) {
105            return equator.equate(iValue, object);
106        }
107        return iValue.equals(object);
108    }
109
110    /**
111     * Gets the value.
112     *
113     * @return the value
114     * @since 3.1
115     */
116    public Object getValue() {
117        return iValue;
118    }
119
120}