vtkBuffer.h

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// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
#ifndef vtkBuffer_h
#define vtkBuffer_h

#include "vtkAbstractBuffer.h"
#include "vtkObjectFactory.h" // New() implementation
#include "vtkTypeTraits.h"    // For vtkTypeTraits

#include <algorithm>   // for std::min and std::copy
#include <type_traits> // for std::is_trivially_copyable

VTK_ABI_NAMESPACE_BEGIN
template <class ScalarTypeT>
class vtkBuffer : public vtkAbstractBuffer
{
public:
  vtkTemplateTypeMacro(vtkBuffer<ScalarTypeT>, vtkAbstractBuffer);
  typedef ScalarTypeT ScalarType;

  static vtkBuffer<ScalarTypeT>* New();
  static vtkBuffer<ScalarTypeT>* ExtendedNew();

  ScalarType* GetBuffer() { return this->Pointer; }
  const ScalarType* GetBuffer() const { return this->Pointer; }

  void SetBuffer(VTK_ZEROCOPY ScalarType* array, vtkIdType size);

  void SetMallocFunction(vtkMallocingFunction mallocFunction = malloc);

  void SetReallocFunction(vtkReallocingFunction reallocFunction = realloc);

  void SetFreeFunction(bool noFreeFunction, vtkFreeingFunction deleteFunction);

  void SetFreeFunction(bool noFreeFunction) { this->SetFreeFunction(noFreeFunction, free); }

  vtkIdType GetSize() const { return this->Size; }


  void* GetVoidBuffer() override { return this->Pointer; }
  vtkIdType GetNumberOfElements() const override { return this->Size; }
  int GetDataType() const override { return vtkTypeTraits<ScalarType>::VTKTypeID(); }
  int GetDataTypeSize() const override { return sizeof(ScalarType); }

  bool Allocate(vtkIdType size);

  bool Reallocate(vtkIdType newsize);

protected:
  vtkBuffer()
    : Pointer(nullptr)
    , Size(0)
  {
    this->SetMallocFunction(vtkObjectBase::GetCurrentMallocFunction());
    this->SetReallocFunction(vtkObjectBase::GetCurrentReallocFunction());
    this->SetFreeFunction(false, vtkObjectBase::GetCurrentFreeFunction());
  }

  ~vtkBuffer() override { this->SetBuffer(nullptr, 0); }

  ScalarType* Pointer;
  vtkIdType Size;
  vtkMallocingFunction MallocFunction;
  vtkReallocingFunction ReallocFunction;
  vtkFreeingFunction DeleteFunction;

private:
  vtkBuffer(const vtkBuffer&) = delete;
  void operator=(const vtkBuffer&) = delete;
};

template <class ScalarT>
inline vtkBuffer<ScalarT>* vtkBuffer<ScalarT>::New()
{
  VTK_STANDARD_NEW_BODY(vtkBuffer<ScalarT>);
}

template <class ScalarT>
inline vtkBuffer<ScalarT>* vtkBuffer<ScalarT>::ExtendedNew()
{
  auto mkhold = vtkMemkindRAII(true);
  return vtkBuffer<ScalarT>::New();
}

//------------------------------------------------------------------------------
template <typename ScalarT>
void vtkBuffer<ScalarT>::SetBuffer(ScalarType* array, vtkIdType sz)
{
  if (this->Pointer != array)
  {
    if (this->DeleteFunction)
    {
      if (this->DeleteFunction != free)
      {
        this->DeleteFunction(this->Pointer);
      }
      else if constexpr (std::is_trivially_destructible_v<ScalarT>)
      {
        free(this->Pointer);
      }
      else
      {
        vtkErrorMacro("SetBuffer is not supported for non-trivially destructible types with free.");
        return;
      }
    }
    this->Pointer = array;
  }
  this->Size = sz;
}
//------------------------------------------------------------------------------
template <typename ScalarT>
void vtkBuffer<ScalarT>::SetMallocFunction(vtkMallocingFunction mallocFunction)
{
  this->MallocFunction = mallocFunction;
}
//------------------------------------------------------------------------------
template <typename ScalarT>
void vtkBuffer<ScalarT>::SetReallocFunction(vtkReallocingFunction reallocFunction)
{
  this->ReallocFunction = reallocFunction;
}

//------------------------------------------------------------------------------
template <typename ScalarT>
void vtkBuffer<ScalarT>::SetFreeFunction(bool noFreeFunction, vtkFreeingFunction deleteFunction)
{
  if (noFreeFunction)
  {
    this->DeleteFunction = nullptr;
  }
  else
  {
    this->DeleteFunction = deleteFunction;
  }
}

//------------------------------------------------------------------------------
template <typename ScalarT>
bool vtkBuffer<ScalarT>::Allocate(vtkIdType size)
{
  // release old memory.
  this->SetBuffer(nullptr, 0);
  if (size > 0)
  {
    ScalarType* newArray = nullptr;
    if (this->MallocFunction && this->MallocFunction != malloc)
    {
      newArray = static_cast<ScalarType*>(this->MallocFunction(size * sizeof(ScalarType)));
    }
    else if constexpr (std::is_trivially_constructible_v<ScalarType>)
    {
      newArray = static_cast<ScalarType*>(malloc(size * sizeof(ScalarType)));
    }
    else
    {
      vtkErrorMacro("Allocate is not supported for non-trivially constructible types with malloc.");
      return false;
    }
    if (newArray)
    {
      this->SetBuffer(newArray, size);
      if (!this->MallocFunction)
      {
        this->DeleteFunction = free;
      }
      return true;
    }
    return false;
  }
  return true; // size == 0
}

//------------------------------------------------------------------------------
template <typename ScalarT>
bool vtkBuffer<ScalarT>::Reallocate(vtkIdType newsize)
{
  if (!this->Pointer || newsize == 0)
  {
    return this->Allocate(newsize);
  }
  if (this->DeleteFunction != free)
  {
    ScalarType* newArray = nullptr;
    if (this->MallocFunction && this->MallocFunction != malloc)
    {
      newArray = static_cast<ScalarType*>(this->MallocFunction(newsize * sizeof(ScalarType)));
    }
    else if constexpr (std::is_trivially_constructible_v<ScalarType>)
    {
      newArray = static_cast<ScalarType*>(malloc(newsize * sizeof(ScalarType)));
    }
    else
    {
      vtkErrorMacro(
        "Reallocate is not supported for non-trivially constructible types with malloc.");
      return false;
    }
    if (!newArray)
    {
      return false;
    }
    // Wrap std::min in parentheses to prevent expansion of the min() macro defined by
    // <windows.h> when NOMINMAX is not set.
    std::copy(this->Pointer, this->Pointer + (std::min)(this->Size, newsize), newArray);
    // now save the new array and release the old one too.
    this->SetBuffer(newArray, newsize);
    // The second check is needed because the array passed in may have been
    // allocated outside the memory management of `vtkBuffer` and therefore
    // have been registered with a `DeleteFunction` such as `delete` or
    // `delete[]`. Since the memory is now allocated with `malloc` here,
    // we must also reset `DeleteFunction` to something which matches.
    if (!this->MallocFunction || this->MallocFunction == malloc)
    {
      this->DeleteFunction = free;
    }
  }
  else
  {
    // Try to reallocate with minimal memory usage and possibly avoid copying.
    ScalarType* newArray = nullptr;
    if (this->ReallocFunction && this->ReallocFunction != realloc)
    {
      newArray = static_cast<ScalarType*>(
        this->ReallocFunction(this->Pointer, newsize * sizeof(ScalarType)));
    }
    else if constexpr (std::is_trivially_copyable_v<ScalarType>)
    {
      newArray = static_cast<ScalarType*>(realloc(this->Pointer, newsize * sizeof(ScalarType)));
    }
    else
    {
      vtkErrorMacro("Reallocate is not supported for non-trivially copyable types with realloc.");
      return false;
    }
    if (!newArray)
    {
      return false;
    }
    this->Pointer = newArray;
    this->Size = newsize;
  }
  return true;
}

VTK_ABI_NAMESPACE_END
#endif
// VTK-HeaderTest-Exclude: vtkBuffer.h