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vtkDataArrayIteratorMacro.h
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vtkDataArrayIteratorMacro.h
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/*=========================================================================
Program: Visualization Toolkit
Module: vtkDataArrayIteratorMacro.h
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
/**
* @def vtkDataArrayIteratorMacro
* @brief (deprecated) A macro for obtaining iterators to
* vtkDataArray data when the array implementation and type are unknown.
*
* @deprecated This macro is deprecated and should not be used any longer. See
* vtkArrayDispatch.h and vtkDataArrayRange.h for replacements.
*
* See vtkTemplateMacro.
* This macro is similar, but defines several additional typedefs and variables
* for safely iterating through data in a vtkAbstractArray container:
* - vtkDAValueType is typedef'd to the array's element value type.
* - vtkDAContainerType is typedef'd to the most derived class of
* vtkAbstractArray for which a suitable iterator has been found.
* - vtkDAIteratorType is typedef'd to the most suitable iterator type found.
* - vtkDABegin is an object of vtkDAIteratorType that points to the first
* component of the first tuple in the array.
* - vtkDAEnd is an object of vtkDAIteratorType that points to the element
* *after* the last component of the last tuple in the array.
* The primary advantage to using this macro is that arrays with non-standard
* memory layouts will be safely handled, and dangerous calls to GetVoidPointer
* are avoided.
* For arrays with > 1 component, the iterator will proceed through all
* components of a tuple before moving on to the next tuple.
* This matches the memory layout of the standard vtkDataArray subclasses such
* as vtkFloatArray.
*
* For the standard vtkDataArray implementations (which are subclasses of
* vtkAOSDataArrayTemplate), the iterators will simply be pointers to the raw
* memory of the array.
* This allows very fast iteration when possible, and permits compiler
* optimizations in the standard template library to occur (such as reducing
* std::copy to memmove).
*
* For arrays that are subclasses of vtkTypedDataArray, a
* vtkTypedDataArrayIterator is used.
* Such iterators safely traverse the array using API calls and have
* pointer-like semantics, but add about a 35% performance overhead compared
* with iterating over the raw memory (measured by summing a vtkFloatArray
* containing 10M values on GCC 4.8.1 with -O3 optimization using both iterator
* types -- see TestDataArrayIterators).
*
* For arrays that are not subclasses of vtkTypedDataArray, there is no reliably
* safe way to iterate over the array elements.
* In such cases, this macro performs the legacy behavior of casting
* vtkAbstractArray::GetVoidPointer(...) to vtkDAValueType* to create the
* iterators.
*
* To use this macro, create a templated worker function:
*
* @code
* template <class Iterator>
* void myFunc(Iterator begin, Iterator end, ...) {...}
*
* and then call the vtkDataArrayIteratorMacro inside of a switch statement
* using the above objects and typedefs as needed:
*
* vtkAbstractArray *someArray = ...;
* switch (someArray->GetDataType())
* {
* vtkDataArrayIteratorMacro(someArray, myFunc(vtkDABegin, vtkDAEnd, ...));
* }
* @endcode
*
* @sa
* vtkArrayDispatch vtkGenericDataArray
* vtkTemplateMacro vtkTypedDataArrayIterator
*/
#ifndef vtkDataArrayIteratorMacro_h
#define vtkDataArrayIteratorMacro_h
#include "vtkAOSDataArrayTemplate.h" // For classes referred to in the macro
#include "vtkSetGet.h" // For vtkTemplateMacro
#include "vtkTypedDataArray.h" // For classes referred to in the macro
// Silence 'unused typedef' warnings on GCC.
// use of the typedef in question depends on the macro
// argument _call and thus should not be removed.
#if defined(__GNUC__)
#define _vtkDAIMUnused __attribute__((unused))
#else
#define _vtkDAIMUnused
#endif
#define vtkDataArrayIteratorMacro(_array, _call) \
vtkTemplateMacro( \
vtkAbstractArray* _aa(_array); if (vtkAOSDataArrayTemplate<VTK_TT>* _dat = \
vtkAOSDataArrayTemplate<VTK_TT>::FastDownCast(_aa)) { \
typedef VTK_TT vtkDAValueType; \
typedef vtkAOSDataArrayTemplate<vtkDAValueType> vtkDAContainerType; \
typedef vtkDAContainerType::Iterator vtkDAIteratorType; \
vtkDAIteratorType vtkDABegin(_dat->Begin()); \
vtkDAIteratorType vtkDAEnd(_dat->End()); \
(void)vtkDABegin; /* Prevent warnings when unused */ \
(void)vtkDAEnd; \
_call; \
} else if (vtkTypedDataArray<VTK_TT>* _tda = vtkTypedDataArray<VTK_TT>::FastDownCast(_aa)) { \
typedef VTK_TT vtkDAValueType; \
typedef vtkTypedDataArray<vtkDAValueType> vtkDAContainerType; \
typedef vtkDAContainerType::Iterator vtkDAIteratorType; \
vtkDAIteratorType vtkDABegin(_tda->Begin()); \
vtkDAIteratorType vtkDAEnd(_tda->End()); \
(void)vtkDABegin; \
(void)vtkDAEnd; \
_call; \
} else { \
/* This is not ideal, as no explicit iterator has been declared. */ \
/* Cast the void pointer and hope for the best! */ \
typedef VTK_TT vtkDAValueType; \
typedef vtkAbstractArray vtkDAContainerType _vtkDAIMUnused; \
typedef vtkDAValueType* vtkDAIteratorType; \
vtkDAIteratorType vtkDABegin = static_cast<vtkDAIteratorType>(_aa->GetVoidPointer(0)); \
vtkDAIteratorType vtkDAEnd = vtkDABegin + _aa->GetMaxId() + 1; \
(void)vtkDABegin; \
(void)vtkDAEnd; \
_call; \
})
#endif // vtkDataArrayIteratorMacro_h
// VTK-HeaderTest-Exclude: vtkDataArrayIteratorMacro.h