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