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    /** The value to compare to */
036    private final T iValue;
037
038    /** The equator to use for comparison */
039    private final Equator<T> equator;
040
041    /**
042     * Factory to create the predicate.
043     *
044     * @param <T> the type that the predicate queries
045     * @param object  the object to compare to
046     * @return the predicate
047     */
048    public static <T> Predicate<T> equalPredicate(final T object) {
049        if (object == null) {
050            return NullPredicate.nullPredicate();
051        }
052        return new EqualPredicate<>(object);
053    }
054
055    /**
056     * Factory to create the identity predicate.
057     *
058     * @param <T> the type that the predicate queries
059     * @param object  the object to compare to
060     * @param equator  the equator to use for comparison
061     * @return the predicate
062     * @since 4.0
063     */
064    public static <T> Predicate<T> equalPredicate(final T object, final Equator<T> equator) {
065        if (object == null) {
066            return NullPredicate.nullPredicate();
067        }
068        return new EqualPredicate<>(object, equator);
069    }
070
071    /**
072     * Constructor that performs no validation.
073     * Use <code>equalPredicate</code> 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</code> 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        super();
093        iValue = object;
094        this.equator = equator;
095    }
096
097    /**
098     * Evaluates the predicate returning true if the input equals the stored value.
099     *
100     * @param object  the input object
101     * @return true if input object equals stored value
102     */
103    @Override
104    public boolean evaluate(final T object) {
105        if (equator != null) {
106            return equator.equate(iValue, object);
107        }
108        return iValue.equals(object);
109    }
110
111    /**
112     * Gets the value.
113     *
114     * @return the value
115     * @since 3.1
116     */
117    public Object getValue() {
118        return iValue;
119    }
120
121}