    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}