1 /*
2  * Copyright 2018 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 package androidx.work
17 
18 /**
19  * An abstract class that allows the user to define how to merge a list of inputs to a
20  * [ListenableWorker].
21  *
22  * Before workers run, they receive input [Data] from their parent workers, as well as anything
23  * specified directly to them via [WorkRequest.Builder.setInputData]. An InputMerger takes all of
24  * these objects and converts them to a single merged [Data] to be used as the worker input.
25  * [WorkManager] offers two concrete InputMerger implementations: [OverwritingInputMerger] and
26  * [ArrayCreatingInputMerger].
27  *
28  * Note that the list of inputs to merge is in an unspecified order. You should not make assumptions
29  * about the order of inputs.
30  */
31 abstract class InputMerger {
32     /**
33      * Merges a list of [Data] and outputs a single Data object.
34      *
35      * @param inputs A list of [Data]
36      * @return The merged output
37      */
mergenull38     abstract fun merge(inputs: List<Data>): Data
39 }
40 
41 private val TAG = Logger.tagWithPrefix("InputMerger")
42 
43 internal fun fromClassName(className: String): InputMerger? {
44     try {
45         val clazz = Class.forName(className)
46         return clazz.getDeclaredConstructor().newInstance() as InputMerger
47     } catch (e: Exception) {
48         Logger.get().error(TAG, "Trouble instantiating $className", e)
49     }
50     return null
51 }
52