1 /* 2 * Copyright (C) 2021 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 #pragma once 18 19 namespace aidl::android::hardware::biometrics { 20 21 // Interface for representing parameterless functions. Unlike std::function<void()>, this can also 22 // represent move-only lambdas. 23 class Callable { 24 public: 25 virtual void operator()() = 0; 26 virtual ~Callable() = default; 27 28 // Creates a heap-allocated Callable instance from any function object. 29 template <typename T> 30 static std::unique_ptr<Callable> from(T func); 31 32 private: 33 template <typename T> 34 class AnyFuncWrapper; 35 }; 36 37 // Private helper class for wrapping any function object into a Callable. 38 template <typename T> 39 class Callable::AnyFuncWrapper : public Callable { 40 public: AnyFuncWrapper(T func)41 explicit AnyFuncWrapper(T func) : mFunc(std::move(func)) {} 42 operator()43 void operator()() override { mFunc(); } 44 45 private: 46 T mFunc; 47 }; 48 49 template <typename T> from(T func)50std::unique_ptr<Callable> Callable::from(T func) { 51 return std::make_unique<AnyFuncWrapper<T>>(std::move(func)); 52 } 53 54 } // namespace aidl::android::hardware::biometrics