1 /*
2  * Copyright (C) 2020 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.android.deskclock
18 
19 /**
20  * A Predicate can determine a true or false value for any input of its
21  * parameterized type. For example, a `RegexPredicate` might implement
22  * `Predicate<String>`, and return true for any String that matches its
23  * given regular expression.
24  *
25  * Implementors of Predicate which may cause side effects upon evaluation are
26  * strongly encouraged to state this fact clearly in their API documentation.
27  */
28 interface Predicate<T> {
applynull29     fun apply(t: T): Boolean
30 
31     companion object {
32         /**
33          * An implementation of the predicate interface that always returns true.
34          */
35         @JvmField
36         val TRUE: Predicate<*> = object : Predicate<Any> {
37             override fun apply(t: Any): Boolean = true
38         }
39 
40         /**
41          * An implementation of the predicate interface that always returns false.
42          */
43         @JvmField
44         val FALSE: Predicate<*> = object : Predicate<Any> {
45             override fun apply(t: Any): Boolean = false
46         }
47     }
48 }