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 *      https://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     * </p>
043     *
044     * @param <E> The type that the closure acts on
045     * @param predicate  predicate to switch on
046     * @param trueClosure  closure used if true
047     * @return The {@code if} closure
048     * @throws NullPointerException if either argument is null
049     * @since 3.2
050     */
051    public static <E> Closure<E> ifClosure(final Predicate<? super E> predicate, final Closure<? super E> trueClosure) {
052        return IfClosure.<E>ifClosure(predicate, trueClosure, NOPClosure.<E>nopClosure());
053    }
054
055    /**
056     * Factory method that performs validation.
057     *
058     * @param <E> The type that the closure acts on
059     * @param predicate  predicate to switch on
060     * @param trueClosure  closure used if true
061     * @param falseClosure  closure used if false
062     * @return The {@code if} closure
063     * @throws NullPointerException if any argument is null
064     */
065    public static <E> Closure<E> ifClosure(final Predicate<? super E> predicate,
066                                           final Closure<? super E> trueClosure,
067                                           final Closure<? super E> falseClosure) {
068        return new IfClosure<>(Objects.requireNonNull(predicate, "predicate"),
069                Objects.requireNonNull(trueClosure, "trueClosure"),
070                Objects.requireNonNull(falseClosure, "falseClosure"));
071    }
072
073    /** The test */
074    private final Predicate<? super T> iPredicate;
075
076    /** The closure to use if true */
077    private final Closure<? super T> iTrueClosure;
078
079    /** The closure to use if false */
080    private final Closure<? super T> iFalseClosure;
081
082    /**
083     * Constructor that performs no validation.
084     * Use {@code ifClosure} if you want that.
085     * <p>
086     * This constructor creates a closure that performs no action when
087     * the predicate is false.
088     * </p>
089     *
090     * @param predicate  predicate to switch on, not null
091     * @param trueClosure  closure used if true, not null
092     * @since 3.2
093     */
094    public IfClosure(final Predicate<? super T> predicate, final Closure<? super T> trueClosure) {
095        this(predicate, trueClosure, NOPClosure.nopClosure());
096    }
097
098    /**
099     * Constructor that performs no validation.
100     * Use {@code ifClosure} if you want that.
101     *
102     * @param predicate  predicate to switch on, not null
103     * @param trueClosure  closure used if true, not null
104     * @param falseClosure  closure used if false, not null
105     */
106    public IfClosure(final Predicate<? super T> predicate, final Closure<? super T> trueClosure,
107                     final Closure<? super T> falseClosure) {
108        iPredicate = predicate;
109        iTrueClosure = trueClosure;
110        iFalseClosure = falseClosure;
111    }
112
113    /**
114     * Executes the true or false closure according to the result of the predicate.
115     *
116     * @param input  The input object
117     */
118    @Override
119    public void execute(final T input) {
120        if (iPredicate.test(input)) {
121            iTrueClosure.accept(input);
122        } else {
123            iFalseClosure.accept(input);
124        }
125    }
126
127    /**
128     * Gets the closure called when false.
129     *
130     * @return The closure
131     * @since 3.1
132     */
133    public Closure<? super T> getFalseClosure() {
134        return iFalseClosure;
135    }
136
137    /**
138     * Gets the predicate.
139     *
140     * @return The predicate
141     * @since 3.1
142     */
143    public Predicate<? super T> getPredicate() {
144        return iPredicate;
145    }
146
147    /**
148     * Gets the closure called when true.
149     *
150     * @return The closure
151     * @since 3.1
152     */
153    public Closure<? super T> getTrueClosure() {
154        return iTrueClosure;
155    }
156
157}