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      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