    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 */
    017
    018package org.apache.commons.io.function;
    019
    020import java.io.IOException;
    021import java.io.UncheckedIOException;
    022import java.util.Objects;
    023import java.util.function.Predicate;
    024
    025/**
    026 * Like {@link Predicate} but throws {@link IOException}.
    027 *
    028 * @param <T> the type of the input to the predicate
    029 * @since 2.12.0
    030 */
    031@FunctionalInterface
    032public interface IOPredicate<T> {
    033
    034    /**
    035     * Always false.
    036     *
    037     * @param <T> the type of the input to the predicate
    038     * @return a constant predicate that tests always false.
    039     */
    040    @SuppressWarnings("unchecked")
    041    static <T> IOPredicate<T> alwaysFalse() {
    042        return (IOPredicate<T>) Constants.IO_PREDICATE_FALSE;
    043    }
    044
    045    /**
    046     * Always true.
    047     *
    048     * @param <T> the type of the input to the predicate
    049     * @return a constant predicate that tests always true.
    050     */
    051    @SuppressWarnings("unchecked")
    052    static <T> IOPredicate<T> alwaysTrue() {
    053        return (IOPredicate<T>) Constants.IO_PREDICATE_TRUE;
    054    }
    055
    056    /**
    057     * Creates a predicate that tests if two arguments are equal using {@link Objects#equals(Object, Object)}.
    058     *
    059     * @param <T> the type of arguments to the predicate
    060     * @param target the object to compare for equality, may be {@code null}
    061     * @return a predicate that tests if two arguments are equal using {@link Objects#equals(Object, Object)}
    062     */
    063    static <T> IOPredicate<T> isEqual(final Object target) {
    064        return null == target ? Objects::isNull : object -> target.equals(object);
    065    }
    066
    067    /**
    068     * Creates a composed predicate that represents a short-circuiting logical AND of this predicate and another. When
    069     * evaluating the composed predicate, if this predicate is {@code false}, then the {@code other} predicate is not
    070     * evaluated.
    071     *
    072     * <p>
    073     * Any exceptions thrown during evaluation of either predicate are relayed to the caller; if evaluation of this
    074     * predicate throws an exception, the {@code other} predicate will not be evaluated.
    075     * </p>
    076     *
    077     * @param other a predicate that will be logically-ANDed with this predicate
    078     * @return a composed predicate that represents the short-circuiting logical AND of this predicate and the {@code other}
    079     *         predicate
    080     * @throws NullPointerException if other is null
    081     */
    082    default IOPredicate<T> and(final IOPredicate<? super T> other) {
    083        Objects.requireNonNull(other);
    084        return t -> test(t) && other.test(t);
    085    }
    086
    087    /**
    088     * Creates a {@link Predicate} for this instance that throws {@link UncheckedIOException} instead of
    089     * {@link IOException}.
    090     *
    091     * @return an UncheckedIOException Predicate.
    092     */
    093    default Predicate<T> asPredicate() {
    094        return t -> Uncheck.test(this, t);
    095    }
    096
    097    /**
    098     * Creates a predicate that represents the logical negation of this predicate.
    099     *
    100     * @return a predicate that represents the logical negation of this predicate
    101     */
    102    default IOPredicate<T> negate() {
    103        return t -> !test(t);
    104    }
    105
    106    /**
    107     * Creates a composed predicate that represents a short-circuiting logical OR of this predicate and another. When
    108     * evaluating the composed predicate, if this predicate is {@code true}, then the {@code other} predicate is not
    109     * evaluated.
    110     *
    111     * <p>
    112     * Any exceptions thrown during evaluation of either predicate are relayed to the caller; if evaluation of this
    113     * predicate throws an exception, the {@code other} predicate will not be evaluated.
    114     * </p>
    115     *
    116     * @param other a predicate that will be logically-ORed with this predicate
    117     * @return a composed predicate that represents the short-circuiting logical OR of this predicate and the {@code other}
    118     *         predicate
    119     * @throws NullPointerException if other is null
    120     */
    121    default IOPredicate<T> or(final IOPredicate<? super T> other) {
    122        Objects.requireNonNull(other);
    123        return t -> test(t) || other.test(t);
    124    }
    125
    126    /**
    127     * Evaluates this predicate on the given argument.
    128     *
    129     * @param t the input argument
    130     * @return {@code true} if the input argument matches the predicate, otherwise {@code false}
    131     * @throws IOException if an I/O error occurs.
    132     */
    133    boolean test(T t) throws IOException;
    134
    135}