    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;
    020import java.util.Objects;
    021
    022import org.apache.commons.collections4.Closure;
    023import org.apache.commons.collections4.Predicate;
    024
    025/**
    026 * Closure implementation acts as an if statement calling one or other closure
    027 * based on a predicate.
    028 *
    029 * @param <T> the type of the input to the operation.
    030 * @since 3.0
    031 */
    032public class IfClosure<T> implements Closure<T>, Serializable {
    033
    034    /** Serial version UID */
    035    private static final long serialVersionUID = 3518477308466486130L;
    036
    037    /**
    038     * Factory method that performs validation.
    039     * <p>
    040     * This factory creates a closure that performs no action when
    041     * the predicate is false.
    042     *
    043     * @param <E> the type that the closure acts on
    044     * @param predicate  predicate to switch on
    045     * @param trueClosure  closure used if true
    046     * @return the {@code if} closure
    047     * @throws NullPointerException if either argument is null
    048     * @since 3.2
    049     */
    050    public static <E> Closure<E> ifClosure(final Predicate<? super E> predicate, final Closure<? super E> trueClosure) {
    051        return IfClosure.<E>ifClosure(predicate, trueClosure, NOPClosure.<E>nopClosure());
    052    }
    053    /**
    054     * Factory method that performs validation.
    055     *
    056     * @param <E> the type that the closure acts on
    057     * @param predicate  predicate to switch on
    058     * @param trueClosure  closure used if true
    059     * @param falseClosure  closure used if false
    060     * @return the {@code if} closure
    061     * @throws NullPointerException if any argument is null
    062     */
    063    public static <E> Closure<E> ifClosure(final Predicate<? super E> predicate,
    064                                           final Closure<? super E> trueClosure,
    065                                           final Closure<? super E> falseClosure) {
    066        return new IfClosure<>(Objects.requireNonNull(predicate, "predicate"),
    067                Objects.requireNonNull(trueClosure, "trueClosure"),
    068                Objects.requireNonNull(falseClosure, "falseClosure"));
    069    }
    070    /** The test */
    071    private final Predicate<? super T> iPredicate;
    072
    073    /** The closure to use if true */
    074    private final Closure<? super T> iTrueClosure;
    075
    076    /** The closure to use if false */
    077    private final Closure<? super T> iFalseClosure;
    078
    079    /**
    080     * Constructor that performs no validation.
    081     * Use {@code ifClosure} if you want that.
    082     * <p>
    083     * This constructor creates a closure that performs no action when
    084     * the predicate is false.
    085     *
    086     * @param predicate  predicate to switch on, not null
    087     * @param trueClosure  closure used if true, not null
    088     * @since 3.2
    089     */
    090    public IfClosure(final Predicate<? super T> predicate, final Closure<? super T> trueClosure) {
    091        this(predicate, trueClosure, NOPClosure.nopClosure());
    092    }
    093
    094    /**
    095     * Constructor that performs no validation.
    096     * Use {@code ifClosure} if you want that.
    097     *
    098     * @param predicate  predicate to switch on, not null
    099     * @param trueClosure  closure used if true, not null
    100     * @param falseClosure  closure used if false, not null
    101     */
    102    public IfClosure(final Predicate<? super T> predicate, final Closure<? super T> trueClosure,
    103                     final Closure<? super T> falseClosure) {
    104        iPredicate = predicate;
    105        iTrueClosure = trueClosure;
    106        iFalseClosure = falseClosure;
    107    }
    108
    109    /**
    110     * Executes the true or false closure according to the result of the predicate.
    111     *
    112     * @param input  the input object
    113     */
    114    @Override
    115    public void execute(final T input) {
    116        if (iPredicate.test(input)) {
    117            iTrueClosure.accept(input);
    118        } else {
    119            iFalseClosure.accept(input);
    120        }
    121    }
    122
    123    /**
    124     * Gets the closure called when false.
    125     *
    126     * @return the closure
    127     * @since 3.1
    128     */
    129    public Closure<? super T> getFalseClosure() {
    130        return iFalseClosure;
    131    }
    132
    133    /**
    134     * Gets the predicate.
    135     *
    136     * @return the predicate
    137     * @since 3.1
    138     */
    139    public Predicate<? super T> getPredicate() {
    140        return iPredicate;
    141    }
    142
    143    /**
    144     * Gets the closure called when true.
    145     *
    146     * @return the closure
    147     * @since 3.1
    148     */
    149    public Closure<? super T> getTrueClosure() {
    150        return iTrueClosure;
    151    }
    152
    153}