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 /** 20 * A [Cantrip] is a transformation of [Data], represented as a function mapping that data to a 21 * mutated or null version of itself. 22 */ 23 interface Cantrip<Data> { 24 /** Applies the [Cantrip] across a single [datum]. */ invokenull25 operator fun invoke(datum: Data): Data? 26 } 27 28 /** 29 * Applies the [Cantrip] across all items in the [sequence]. 30 * 31 * If a given return value from the [Cantrip] is null, the data is omitted from the sequence. 32 */ 33 operator fun <Data> Cantrip<Data>.invoke(sequence: Sequence<Data>): Sequence<Data> = 34 sequence.mapNotNull(::invoke) 35 36 /** Applies the [Cantrip] across all items in the [List]. */ 37 operator fun <Data> Cantrip<Data>.invoke(list: List<Data>): List<Data> = 38 invoke(list.asSequence()).toList() 39 40 /** Applies the [Cantrip] across all items in the [Set]. */ 41 operator fun <Data> Cantrip<Data>.invoke(set: Set<Data>): Set<Data> = 42 invoke(set.asSequence()).toSet() 43