1 /*
2  * Copyright (C) 2022 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.libraries.pcc.chronicle.api.cantrip
18 
19 import com.android.libraries.pcc.chronicle.api.operation.Action
20 import com.android.libraries.pcc.chronicle.api.operation.Operation
21 import com.android.libraries.pcc.chronicle.api.optics.Traversal
22 
23 /**
24  * A [Cantrip] composed of an optical [Traversal] and an [Operation].
25  *
26  * When [invoked][invoke], the operation is applied to the focused value of type [Field] within the
27  * [Data]. If the operation returns [Action.OmitFromParent] or [Action.OmitFromRoot], `null` is
28  * returned.
29  */
30 class OpticalCantrip<Data, Field>(
31   private val optic: Traversal<Data, Data, Field, Field>,
32   private val operation: Operation<Field, Field>
33 ) : Cantrip<Data> {
invokenull34   override fun invoke(datum: Data): Data? {
35     return when (val result = optic.modifyWithAction(datum, operation)) {
36       Action.OmitFromParent, Action.OmitFromRoot -> null
37       is Action.Throw -> throw result.exception
38       is Action.Update -> result.newValue
39     }
40   }
41 }
42