1 /*
2  * Copyright (C) 2015 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 class AudioPolicyManagerInterface;
20 class AudioPolicyPluginInterface;
21 
22 namespace android
23 {
24 namespace audio_policy
25 {
26 
27 class Engine;
28 
29 class EngineInstance
30 {
31 protected:
32     EngineInstance();
33 
34 public:
35     virtual ~EngineInstance();
36 
37     /**
38      * Get Audio Policy Engine instance.
39      *
40      * @return pointer to Route Manager Instance object.
41      */
42     static EngineInstance *getInstance();
43 
44     /**
45      * Interface query.
46      * The first client of an interface of the policy engine will start the singleton.
47      *
48      * @tparam RequestedInterface: interface that the client is wishing to retrieve.
49      *
50      * @return interface handle.
51      */
52     template <class RequestedInterface>
53     RequestedInterface *queryInterface() const;
54 
55 protected:
56     /**
57      * Get Audio Policy Engine instance.
58      *
59      * @return Audio Policy Engine singleton.
60      */
61     Engine *getEngine() const;
62 
63 private:
64     /* Copy facilities are put private to disable copy. */
65     EngineInstance(const EngineInstance &object);
66     EngineInstance &operator=(const EngineInstance &object);
67 };
68 
69 /**
70  * Limit template instantation to supported type interfaces.
71  * Compile time error will claim if invalid interface is requested.
72  */
73 template <>
74 AudioPolicyManagerInterface *EngineInstance::queryInterface() const;
75 
76 template <>
77 AudioPolicyPluginInterface *EngineInstance::queryInterface() const;
78 
79 }; // namespace audio_policy
80 
81 }; // namespace android
82