text: /*
   *  Copyright 2019-2021 Diligent Graphics LLC
   *  Copyright 2015-2019 Egor Yusov
   *  
   *  Licensed under the Apache License, Version 2.0 (the "License");
   *  you may not use this file except in compliance with the License.
   *  You may obtain a copy of the License at
   *  
   *      http://www.apache.org/licenses/LICENSE-2.0
   *  
   *  Unless required by applicable law or agreed to in writing, software
   *  distributed under the License is distributed on an "AS IS" BASIS,
   *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *  See the License for the specific language governing permissions and
   *  limitations under the License.
   *
   *  In no event and under no legal theory, whether in tort (including negligence), 
   *  contract, or otherwise, unless required by applicable law (such as deliberate 
   *  and grossly negligent acts) or agreed to in writing, shall any Contributor be
   *  liable for any damages, including any direct, indirect, special, incidental, 
   *  or consequential damages of any character arising as a result of this License or 
   *  out of the use or inability to use the software (including but not limited to damages 
   *  for loss of goodwill, work stoppage, computer failure or malfunction, or any and 
   *  all other commercial damages or losses), even if such Contributor has been advised 
   *  of the possibility of such damages.
   */
  
  #pragma once
  
  /// \file
  /// Implementation of the Diligent::EngineFactoryBase template class
  
  #include "Object.h"
  #include "EngineFactory.h"
  #include "DefaultShaderSourceStreamFactory.h"
  
  namespace Diligent
  {
  
  const APIInfo& GetAPIInfo();
  
  /// Template class implementing base functionality of the engine factory
  
  /// \tparam BaseInterface - Base interface that this class will inherit
  ///                         (Diligent::IEngineFactoryD3D11, Diligent::IEngineFactoryD3D12,
  ///                          Diligent::IEngineFactoryVk or Diligent::IEngineFactoryOpenGL).
  template <class BaseInterface>
  class EngineFactoryBase : public BaseInterface
  {
  public:
      EngineFactoryBase(const INTERFACE_ID& FactoryIID) noexcept :
          // clang-format off
          m_FactoryIID  {FactoryIID},
          m_RefCounters {*this     }
      // clang-format on
      {
      }
  
      virtual void DILIGENT_CALL_TYPE QueryInterface(const INTERFACE_ID& IID, IObject** ppInterface) override final
      {
          if (ppInterface == nullptr)
              return;
  
          *ppInterface = nullptr;
          if (IID == IID_Unknown || IID == m_FactoryIID || IID == IID_EngineFactory)
          {
              *ppInterface = this;
              (*ppInterface)->AddRef();
          }
      }
  
      virtual ReferenceCounterValueType DILIGENT_CALL_TYPE AddRef() override final
      {
          return m_RefCounters.AddStrongRef();
      }
  
      virtual ReferenceCounterValueType DILIGENT_CALL_TYPE Release() override final
      {
          return m_RefCounters.ReleaseStrongRef();
      }
  
      virtual IReferenceCounters* DILIGENT_CALL_TYPE GetReferenceCounters() const override final
      {
          return const_cast<IReferenceCounters*>(static_cast<const IReferenceCounters*>(&m_RefCounters));
      }
  
      virtual const APIInfo& DILIGENT_CALL_TYPE GetAPIInfo() const override final
      {
          return Diligent::GetAPIInfo();
      }
  
      virtual void DILIGENT_CALL_TYPE CreateDefaultShaderSourceStreamFactory(const Char*                       SearchDirectories,
                                                                             IShaderSourceInputStreamFactory** ppShaderSourceFactory) const override final
      {
          Diligent::CreateDefaultShaderSourceStreamFactory(SearchDirectories, ppShaderSourceFactory);
      }
  
  private:
      class DummyReferenceCounters final : public IReferenceCounters
      {
      public:
          DummyReferenceCounters(EngineFactoryBase& Factory) noexcept :
              m_Factory{Factory}
          {
              m_lNumStrongReferences = 0;
              m_lNumWeakReferences   = 0;
          }
  
          virtual ReferenceCounterValueType AddStrongRef() override final
          {
              return Atomics::AtomicIncrement(m_lNumStrongReferences);
          }
  
          virtual ReferenceCounterValueType ReleaseStrongRef() override final
          {
              return Atomics::AtomicDecrement(m_lNumStrongReferences);
          }
  
          virtual ReferenceCounterValueType AddWeakRef() override final
          {
              return Atomics::AtomicIncrement(m_lNumWeakReferences);
          }
  
          virtual ReferenceCounterValueType ReleaseWeakRef() override final
          {
              return Atomics::AtomicDecrement(m_lNumWeakReferences);
          }
  
          virtual void GetObject(IObject** ppObject) override final
          {
              if (ppObject != nullptr)
                  m_Factory.QueryInterface(IID_Unknown, ppObject);
          }
  
          virtual ReferenceCounterValueType GetNumStrongRefs() const override final
          {
              return m_lNumStrongReferences;
          }
  
          virtual ReferenceCounterValueType GetNumWeakRefs() const override final
          {
              return m_lNumWeakReferences;
          }
  
      private:
          EngineFactoryBase&  m_Factory;
          Atomics::AtomicLong m_lNumStrongReferences;
          Atomics::AtomicLong m_lNumWeakReferences;
      };
  
      const INTERFACE_ID     m_FactoryIID;
      DummyReferenceCounters m_RefCounters;
  };
  
  } // namespace Diligent
  