1 /*
2  * Copyright (C) 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 
17 #ifndef ANDROID_HARDWARE_AUDIO_COMMON_TEST_UTILITY_RETURN_IN_H
18 #define ANDROID_HARDWARE_AUDIO_COMMON_TEST_UTILITY_RETURN_IN_H
19 
20 #include <tuple>
21 
22 namespace android {
23 namespace hardware {
24 namespace audio {
25 namespace common {
26 namespace test {
27 namespace utility {
28 
29 namespace detail {
30 // Helper class to generate the HIDL synchronous callback
31 template <class... ResultStore>
32 class ReturnIn {
33    public:
34     // Provide to the constructor the variables where the output parameters must be copied
35     // TODO: take pointers to match google output parameter style ?
ReturnIn(ResultStore &...ts)36     ReturnIn(ResultStore&... ts) : results(ts...) {}
37     // Synchronous callback
38     template <class... Results>
operator()39     void operator()(Results&&... results) {
40         set(std::forward<Results>(results)...);
41     }
42 
43    private:
44     // Recursively set all output parameters
45     template <class Head, class... Tail>
set(Head && head,Tail &&...tail)46     void set(Head&& head, Tail&&... tail) {
47         std::get<sizeof...(ResultStore) - sizeof...(Tail) - 1>(results) = std::forward<Head>(head);
48         set(std::forward<Tail>(tail)...);
49     }
50     // Trivial case
set()51     void set() {}
52 
53     // All variables to set are stored here
54     std::tuple<ResultStore&...> results;
55 };
56 }  // namespace detail
57 
58 // Generate the HIDL synchronous callback with a copy policy
59 // Input: the variables (lvalue references) where to copy the return values
60 // Output: the callback to provide to a HIDL call with a synchronous callback
61 // The output parameters *will be copied* do not use this function if you have
62 // a zero copy policy
63 template <class... ResultStore>
returnIn(ResultStore &...ts)64 detail::ReturnIn<ResultStore...> returnIn(ResultStore&... ts) {
65     return {ts...};
66 }
67 
68 }  // namespace utility
69 }  // namespace test
70 }  // namespace common
71 }  // namespace audio
72 }  // namespace hardware
73 }  // namespace android
74 
75 #endif  // ANDROID_HARDWARE_AUDIO_COMMON_TEST_UTILITY_RETURN_IN_H
76