itkObjectStore.h

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/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  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
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  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.
 *
 *=========================================================================*/
#ifndef itkObjectStore_h
#define itkObjectStore_h
 
#include "itkObjectFactory.h"
#include "itkObject.h"
#include "itkIntTypes.h"
#include <vector>
 
namespace itk
{
class ObjectStoreEnums
{
public:
  enum class GrowthStrategy : uint8_t
  {
    LINEAR_GROWTH = 0,
    EXPONENTIAL_GROWTH = 1
  };
};
extern ITKCommon_EXPORT std::ostream &
                        operator<<(std::ostream & out, const ObjectStoreEnums::GrowthStrategy value);

template <typename TObjectType>
class ITK_TEMPLATE_EXPORT ObjectStore : public Object
{
public:
  ITK_DISALLOW_COPY_AND_MOVE(ObjectStore);

  using Self = ObjectStore;
  using Superclass = Object;
  using Pointer = SmartPointer<Self>;
  using ConstPointer = SmartPointer<const Self>;

  itkNewMacro(Self);

  itkOverrideGetNameOfClassMacro(ObjectStore);

  using ObjectType = TObjectType;

  using FreeListType = std::vector<ObjectType *>;
 
  using GrowthStrategyEnum = ObjectStoreEnums::GrowthStrategy;
#if !defined(ITK_LEGACY_REMOVE)
  // We need to expose the enum values at the class level
  // for backwards compatibility
  static constexpr GrowthStrategyEnum LINEAR_GROWTH = GrowthStrategyEnum::LINEAR_GROWTH;
  static constexpr GrowthStrategyEnum EXPONENTIAL_GROWTH = GrowthStrategyEnum::EXPONENTIAL_GROWTH;
#endif
  ObjectType *
  Borrow();

  void
  Return(ObjectType * p);

  itkGetConstMacro(Size, SizeValueType);

  void
  Reserve(SizeValueType n);

  void
  Squeeze();

  void
  Clear();

  itkSetMacro(LinearGrowthSize, SizeValueType);
  itkGetConstMacro(LinearGrowthSize, SizeValueType);

  itkSetEnumMacro(GrowthStrategy, GrowthStrategyEnum);
  itkGetConstMacro(GrowthStrategy, GrowthStrategyEnum);

  void
  SetGrowthStrategyToExponential()
  {
    this->SetGrowthStrategy(GrowthStrategyEnum::EXPONENTIAL_GROWTH);
  }

  void
  SetGrowthStrategyToLinear()
  {
    this->SetGrowthStrategy(GrowthStrategyEnum::LINEAR_GROWTH);
  }
 
protected:
  ObjectStore() = default;
  ~ObjectStore() override;
  void
  PrintSelf(std::ostream & os, Indent indent) const override;

  SizeValueType
  GetGrowthSize();
 
  struct MemoryBlock
  {
    MemoryBlock() = default;
 
    MemoryBlock(SizeValueType n)
      : Size(n)
    {
      Begin = new ObjectType[n];
    }
 
    ~MemoryBlock() = default; // Purposely does *not* free memory
 
    void
    Delete()
    {
      delete[] Begin;
    }
 
    ObjectType *  Begin{};
    SizeValueType Size{ 0 };
  };
 
private:
  GrowthStrategyEnum m_GrowthStrategy{ GrowthStrategyEnum::EXPONENTIAL_GROWTH };
 
  SizeValueType m_Size{};
  SizeValueType m_LinearGrowthSize{ 1024 };

  FreeListType m_FreeList{};

  std::vector<MemoryBlock> m_Store{};
};
 
} // end namespace itk
 
#ifndef ITK_MANUAL_INSTANTIATION
#  include "itkObjectStore.hxx"
#endif
 
#endif