1607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller/*
2607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
3607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller *
5607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * This code is free software; you can redistribute it and/or modify it
6607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * under the terms of the GNU General Public License version 2 only, as
7607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * published by the Free Software Foundation.  Oracle designates this
8607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * particular file as subject to the "Classpath" exception as provided
9607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * by Oracle in the LICENSE file that accompanied this code.
10607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller *
11607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * This code is distributed in the hope that it will be useful, but WITHOUT
12607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * version 2 for more details (a copy is included in the LICENSE file that
15607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * accompanied this code).
16607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller *
17607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * You should have received a copy of the GNU General Public License version
18607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * 2 along with this work; if not, write to the Free Software Foundation,
19607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller *
21607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * or visit www.oracle.com if you need additional information or have any
23607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * questions.
24607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller */
25607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fullerpackage java.util.function;
26607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller
27607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fullerimport java.util.Objects;
28607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller
29607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller/**
30607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * Represents a predicate (boolean-valued function) of one argument.
31607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller *
32607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * <p>This is a <a href="package-summary.html">functional interface</a>
33607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * whose functional method is {@link #test(Object)}.
34607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller *
35607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * @param <T> the type of the input to the predicate
36607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller *
37607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller * @since 1.8
38607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller */
39607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller@FunctionalInterface
40607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fullerpublic interface Predicate<T> {
41607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller
42607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    /**
43607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * Evaluates this predicate on the given argument.
44607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     *
45607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @param t the input argument
46607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @return {@code true} if the input argument matches the predicate,
47607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * otherwise {@code false}
48607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     */
49607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    boolean test(T t);
50607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller
51607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    /**
52607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * Returns a composed predicate that represents a short-circuiting logical
53607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * AND of this predicate and another.  When evaluating the composed
54607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * predicate, if this predicate is {@code false}, then the {@code other}
55607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * predicate is not evaluated.
56607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     *
57607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * <p>Any exceptions thrown during evaluation of either predicate are relayed
58607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * to the caller; if evaluation of this predicate throws an exception, the
59607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * {@code other} predicate will not be evaluated.
60607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     *
61607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @param other a predicate that will be logically-ANDed with this
62607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     *              predicate
63607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @return a composed predicate that represents the short-circuiting logical
64607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * AND of this predicate and the {@code other} predicate
65607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @throws NullPointerException if other is null
66607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     */
67607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    default Predicate<T> and(Predicate<? super T> other) {
68607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller        Objects.requireNonNull(other);
69607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller        return (t) -> test(t) && other.test(t);
70607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    }
71607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller
72607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    /**
73607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * Returns a predicate that represents the logical negation of this
74607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * predicate.
75607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     *
76607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @return a predicate that represents the logical negation of this
77607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * predicate
78607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     */
79607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    default Predicate<T> negate() {
80607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller        return (t) -> !test(t);
81607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    }
82607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller
83607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    /**
84607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * Returns a composed predicate that represents a short-circuiting logical
85607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * OR of this predicate and another.  When evaluating the composed
86607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * predicate, if this predicate is {@code true}, then the {@code other}
87607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * predicate is not evaluated.
88607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     *
89607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * <p>Any exceptions thrown during evaluation of either predicate are relayed
90607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * to the caller; if evaluation of this predicate throws an exception, the
91607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * {@code other} predicate will not be evaluated.
92607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     *
93607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @param other a predicate that will be logically-ORed with this
94607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     *              predicate
95607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @return a composed predicate that represents the short-circuiting logical
96607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * OR of this predicate and the {@code other} predicate
97607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @throws NullPointerException if other is null
98607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     */
99607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    default Predicate<T> or(Predicate<? super T> other) {
100607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller        Objects.requireNonNull(other);
101607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller        return (t) -> test(t) || other.test(t);
102607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    }
103607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller
104607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    /**
105607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * Returns a predicate that tests if two arguments are equal according
106607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * to {@link Objects#equals(Object, Object)}.
107607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     *
108607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @param <T> the type of arguments to the predicate
109607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @param targetRef the object reference with which to compare for equality,
110607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     *               which may be {@code null}
111607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * @return a predicate that tests if two arguments are equal according
112607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     * to {@link Objects#equals(Object, Object)}
113607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller     */
114607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    static <T> Predicate<T> isEqual(Object targetRef) {
115607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller        return (null == targetRef)
116607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller                ? Objects::isNull
117607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller                : object -> targetRef.equals(object);
118607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller    }
119607050af5a16c46ae53ff4d2c3f47b4ef694b559Neil Fuller}
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