STYLE: Use auto for variable type matches

This check is responsible for using the auto type specifier for variable
declarations to improve code readability and maintainability.

The auto type specifier will only be introduced in situations where the
variable type matches the type of the initializer expression. In other words
auto should deduce the same type that was originally spelled in the source

Remove statements that are not used.

Replace using statements for enums with named enums.

Modules/Core/Common/include/itkBoundingBox.hxx

@@ -287,7 +287,7 @@ auto
 BoundingBox<TPointIdentifier, VPointDimension, TCoordinate, TPointsContainer>::GetDiagonalLength2() const
   -> AccumulateType
 {
-  typename NumericTraits<CoordinateType>::AccumulateType dist2 = CoordinateType{};
+  typename NumericTraits<CoordinateType>::AccumulateType dist2{};
 
   if (this->ComputeBoundingBox())
   {

Modules/Core/Common/include/itkColorTable.hxx

@@ -242,11 +242,11 @@ ColorTable<TComponent>::UseRandomColors(unsigned int n)
   }
   for (unsigned int i = 0; i < n; ++i)
   {
-    TComponent r = static_cast<TComponent>(vnl_sample_uniform(minimum, maximum));
+    auto r = static_cast<TComponent>(vnl_sample_uniform(minimum, maximum));
     m_Color[i][0] = r;
-    TComponent g = static_cast<TComponent>(vnl_sample_uniform(minimum, maximum));
+    auto g = static_cast<TComponent>(vnl_sample_uniform(minimum, maximum));
     m_Color[i][1] = g;
-    TComponent b = static_cast<TComponent>(vnl_sample_uniform(minimum, maximum));
+    auto b = static_cast<TComponent>(vnl_sample_uniform(minimum, maximum));
     m_Color[i][2] = b;
     std::ostringstream name;
     name << "Random(" << std::fixed << std::setprecision(2) << static_cast<float>(r) << ',' << static_cast<float>(g)

Modules/Core/Common/include/itkCovariantVector.hxx

@@ -113,7 +113,7 @@ template <typename T, unsigned int VVectorDimension>
 typename CovariantVector<T, VVectorDimension>::ValueType
 CovariantVector<T, VVectorDimension>::operator*(const Vector<T, VVectorDimension> & other) const
 {
-  typename NumericTraits<T>::AccumulateType value = T{};
+  typename NumericTraits<T>::AccumulateType value{};
   for (unsigned int i = 0; i < VVectorDimension; ++i)
   {
     value += (*this)[i] * other[i];

Modules/Core/Common/include/itkGaussianOperator.hxx

@@ -53,7 +53,7 @@ GaussianOperator<TPixel, VDimension, TAllocator>::GenerateCoefficients() -> Coef
     }
   }
   // Normalize the coefficients so that their sum is one.
-  for (typename CoefficientVector::iterator it = coeff.begin(); it < coeff.end(); ++it)
+  for (auto it = coeff.begin(); it < coeff.end(); ++it)
   {
     *it /= sum;
   }
@@ -63,7 +63,7 @@ GaussianOperator<TPixel, VDimension, TAllocator>::GenerateCoefficients() -> Coef
   coeff.insert(coeff.begin(), j, 0);
   {
     int i = 0;
-    for (typename CoefficientVector::iterator it = coeff.end() - 1; i < j; --it, ++i)
+    for (auto it = coeff.end() - 1; i < j; --it, ++i)
     {
       coeff[i] = *it;
     }

Modules/Core/Common/include/itkMacro.h

@@ -343,7 +343,7 @@ namespace itk
 #define itkFactorylessNewMacro(x) \
   static Pointer New()            \
   {                               \
-    x *     rawPtr = new x();     \
+    auto *  rawPtr = new x();     \
     Pointer smartPtr = rawPtr;    \
     rawPtr->UnRegister();         \
     return smartPtr;              \

Modules/Core/Common/include/itkNeighborhoodIterator.hxx

@@ -125,7 +125,7 @@ NeighborhoodIterator<TImage, TBoundaryCondition>::SetPixel(const unsigned int n,
       if (!this->m_InBounds[i]) // Part of dimension spills out of bounds
       {
         const typename OffsetType::OffsetValueType OverlapLow = this->m_InnerBoundsLow[i] - this->m_Loop[i];
-        const typename OffsetType::OffsetValueType OverlapHigh =
+        const auto                                 OverlapHigh =
           static_cast<OffsetValueType>(this->GetSize(i) - ((this->m_Loop[i] + 2) - this->m_InnerBoundsHigh[i]));
         if (temp[i] < OverlapLow || OverlapHigh < temp[i])
         {

Modules/Core/Common/include/itkResourceProbesCollectorBase.hxx

@@ -67,8 +67,8 @@ template <typename TProbe>
 void
 ResourceProbesCollectorBase<TProbe>::Report(std::ostream & os, bool printSystemInfo, bool printReportHead, bool useTabs)
 {
-  auto                                   probe = this->m_Probes.begin();
-  const typename MapType::const_iterator end = this->m_Probes.end();
+  auto       probe = this->m_Probes.begin();
+  const auto end = this->m_Probes.end();
 
   if (probe == end)
   {
@@ -122,8 +122,8 @@ ResourceProbesCollectorBase<TProbe>::ExpandedReport(std::ostream & os,
                                                     bool           printReportHead,
                                                     bool           useTabs)
 {
-  auto                                   probe = this->m_Probes.begin();
-  const typename MapType::const_iterator end = this->m_Probes.end();
+  auto       probe = this->m_Probes.begin();
+  const auto end = this->m_Probes.end();
 
   if (probe == end)
   {
@@ -174,8 +174,8 @@ template <typename TProbe>
 void
 ResourceProbesCollectorBase<TProbe>::JSONReport(std::ostream & os, bool printSystemInfo)
 {
-  auto                                   probe = this->m_Probes.begin();
-  const typename MapType::const_iterator end = this->m_Probes.end();
+  auto       probe = this->m_Probes.begin();
+  const auto end = this->m_Probes.end();
 
   if (probe == end)
   {

Modules/Core/Common/include/itkSparseFieldLayer.hxx

@@ -51,9 +51,8 @@ auto
 SparseFieldLayer<TNodeType>::SplitRegions(int num) const -> RegionListType
 {
   const unsigned int size = Size();
-  const unsigned int regionsize =
-    static_cast<unsigned int>(std::ceil(static_cast<float>(size) / static_cast<float>(num)));
-  ConstIterator       position = Begin();
+  const auto    regionsize = static_cast<unsigned int>(std::ceil(static_cast<float>(size) / static_cast<float>(num)));
+  ConstIterator position = Begin();
   const ConstIterator last = End();
 
   std::vector<RegionType> regionlist;

Modules/Core/Common/include/itkThreadLogger.h

@@ -59,14 +59,14 @@ class ITKCommon_EXPORT ThreadLogger : public Logger
   using DelayType = unsigned int;
 
   /** Definition of types of operations for ThreadLogger. */
-  typedef enum
+  enum OperationType
   {
     SET_PRIORITY_LEVEL,
     SET_LEVEL_FOR_FLUSHING,
     ADD_LOG_OUTPUT,
     WRITE,
     FLUSH
-  } OperationType;
+  };
 
   /** Set the priority level for the current logger. Only messages that have
    * priorities equal or greater than the one set here will be posted to the

Modules/Core/Common/include/itkVector.hxx

@@ -103,7 +103,7 @@ template <typename T, unsigned int TVectorDimension>
 auto
 Vector<T, TVectorDimension>::GetSquaredNorm() const -> RealValueType
 {
-  typename NumericTraits<RealValueType>::AccumulateType sum = T{};
+  auto sum = T{};
   for (unsigned int i = 0; i < TVectorDimension; ++i)
   {
     const RealValueType value = (*this)[i];
@@ -198,7 +198,7 @@ template <typename T, unsigned int TVectorDimension>
 typename Vector<T, TVectorDimension>::ValueType
 Vector<T, TVectorDimension>::operator*(const Self & other) const
 {
-  typename NumericTraits<T>::AccumulateType value = T{};
+  auto value = T{};
   for (unsigned int i = 0; i < TVectorDimension; ++i)
   {
     value += (*this)[i] * other[i];

Modules/Core/Common/src/itkMetaDataDictionary.cxx

@@ -44,7 +44,7 @@ void
 MetaDataDictionary::Print(std::ostream & os) const
 {
   os << "Dictionary use_count: " << m_Dictionary.use_count() << std::endl;
-  for (MetaDataDictionaryMapType::const_iterator it = m_Dictionary->begin(); it != m_Dictionary->end(); ++it)
+  for (auto it = m_Dictionary->begin(); it != m_Dictionary->end(); ++it)
   {
     os << it->first << "  ";
     it->second->Print(os);
@@ -102,7 +102,7 @@ MetaDataDictionary::GetKeys() const
   using VectorType = std::vector<std::string>;
   VectorType ans;
 
-  for (MetaDataDictionaryMapType::const_iterator it = m_Dictionary->begin(); it != m_Dictionary->end(); ++it)
+  for (auto it = m_Dictionary->begin(); it != m_Dictionary->end(); ++it)
   {
     ans.push_back(it->first);
   }
@@ -179,8 +179,8 @@ MetaDataDictionary::MakeUnique()
 bool
 MetaDataDictionary::Erase(const std::string & key)
 {
-  auto                                      it = m_Dictionary->find(key);
-  const MetaDataDictionaryMapType::iterator end = m_Dictionary->end();
+  auto       it = m_Dictionary->find(key);
+  const auto end = m_Dictionary->end();
 
   if (it != end)
   {

Modules/Core/Common/src/itkObjectFactoryBase.cxx

@@ -130,8 +130,8 @@ class ObjectFactoryBase::ObjectFactoryBasePrivate : public LightObject
 auto
 ObjectFactoryBase::GetPimplGlobalsPointer() -> ObjectFactoryBasePrivate *
 {
-  const auto                 deleteLambda = []() { m_PimplGlobals->UnRegister(); };
-  ObjectFactoryBasePrivate * globalInstance = Singleton<ObjectFactoryBasePrivate>("ObjectFactoryBase", deleteLambda);
+  const auto deleteLambda = []() { m_PimplGlobals->UnRegister(); };
+  auto *     globalInstance = Singleton<ObjectFactoryBasePrivate>("ObjectFactoryBase", deleteLambda);
   if (globalInstance != m_PimplGlobals)
   {
     SynchronizeObjectFactoryBase(globalInstance);

Modules/Core/Common/src/itkProcessObject.cxx

@@ -434,7 +434,7 @@ ProcessObject::SetOutput(const DataObjectIdentifierType & name, DataObject * out
   }
 
   // does this change anything?
-  const DataObjectPointerMap::const_iterator it = m_Outputs.find(key);
+  const auto it = m_Outputs.find(key);
   if (it != m_Outputs.end() && it->second.GetPointer() == output)
   {
     return;

Modules/Core/Common/test/itkConstShapedNeighborhoodIteratorTest.cxx

@@ -300,8 +300,8 @@ itkConstShapedNeighborhoodIteratorTest(int, char *[])
   std::cout << "it.GetActiveIndexListSize()=" << it.GetActiveIndexListSize();
 
   println("Testing GetActiveIndexList()");
-  itk::ConstShapedNeighborhoodIterator<TestImageType>::IndexListType                  l = it.GetActiveIndexList();
-  itk::ConstShapedNeighborhoodIterator<TestImageType>::IndexListType ::const_iterator ali = l.begin();
+  itk::ConstShapedNeighborhoodIterator<TestImageType>::IndexListType l = it.GetActiveIndexList();
+  auto                                                               ali = l.begin();
   while (ali != l.end())
   {
     std::cout << *ali << ' ';

Modules/Core/Common/test/itkImageTest.cxx

@@ -174,7 +174,7 @@ itkImageTest(int, char *[])
   volume->SetRegions(cuboid);
 
   using ProjectionTransformType = TestTransform<Image3D::ImageDimension>;
-  ProjectionTransformType * projectionTransform = new ProjectionTransformType;
+  auto * projectionTransform = new ProjectionTransformType;
 
   const Image::RegionType rectangleRegion = itk::ImageAlgorithm::EnlargeRegionOverBox(
     volume->GetLargestPossibleRegion(), volume.GetPointer(), imageRef.GetPointer(), projectionTransform);
@@ -192,7 +192,7 @@ itkImageTest(int, char *[])
   }
 
   using TestIdentityTransformType = TestTransform<Image::ImageDimension>;
-  TestIdentityTransformType * testIdentityTransform = new TestIdentityTransformType;
+  auto * testIdentityTransform = new TestIdentityTransformType;
 
   const Image::RegionType tesBoxRegion = itk::ImageAlgorithm::EnlargeRegionOverBox(
     image->GetLargestPossibleRegion(), image.GetPointer(), imageRef.GetPointer(), testIdentityTransform);

Modules/Core/Common/test/itkLineIteratorTest.cxx

@@ -114,7 +114,7 @@ itkLineIteratorTest(int argc, char * argv[])
   endIndex.Fill(189);
   LineIteratorType it(output, startIndex, endIndex);
 
-  std::vector<IndexType>::iterator itBaseline = baselineIndex.begin();
+  auto itBaseline = baselineIndex.begin();
   while (!it.IsAtEnd())
   {
     it.Set(255);

Modules/Core/Common/test/itkMathRoundProfileTest1.cxx

@@ -98,10 +98,10 @@ itkMathRoundProfileTest1(int, char *[])
     // Count the time of simply assigning values in an std::vector
     //
     //
-    IntArrayType::const_iterator outItr1src = output1.begin();
-    auto                         outItr2dst = output2.begin();
+    auto outItr1src = output1.begin();
+    auto outItr2dst = output2.begin();
 
-    const IntArrayType::const_iterator outEnd1 = output1.end();
+    const auto outEnd1 = output1.end();
 
     chronometer.Start("std::vector");
 
@@ -112,8 +112,8 @@ itkMathRoundProfileTest1(int, char *[])
 
     chronometer.Stop("std::vector");
 
-    ArrayType::const_iterator inpItr = input.begin();
-    ArrayType::const_iterator inputEnd = input.end();
+    auto inpItr = input.begin();
+    auto inputEnd = input.end();
 
     auto outItr1nc = output1.begin();
 
@@ -191,11 +191,11 @@ itkMathRoundProfileTest1(int, char *[])
   //
   // Now test the correctness of the output
   //
-  ArrayType::const_iterator       inpItr = input.begin();
-  const ArrayType::const_iterator inputEnd = input.end();
+  auto       inpItr = input.begin();
+  const auto inputEnd = input.end();
 
-  IntArrayType::const_iterator outItr1 = output1.begin();
-  IntArrayType::const_iterator outItr2 = output2.begin();
+  auto outItr1 = output1.begin();
+  auto outItr2 = output2.begin();
 
   bool roundMismatch = false;
 

Modules/Core/Common/test/itkObjectFactoryOnlyNewTest.cxx

@@ -157,14 +157,14 @@ itkObjectFactoryOnlyNewTest(int, char *[])
     std::cout << "  Factory version: " << oneFactory->GetITKSourceVersion() << std::endl
               << "  Factory description: " << oneFactory->GetDescription() << std::endl;
 
-    std::list<std::string>                 overrides = oneFactory->GetClassOverrideNames();
-    std::list<std::string>                 names = oneFactory->GetClassOverrideWithNames();
-    std::list<std::string>                 descriptions = oneFactory->GetClassOverrideDescriptions();
-    std::list<bool>                        enableflags = oneFactory->GetEnableFlags();
-    std::list<std::string>::const_iterator n = names.begin();
-    std::list<std::string>::const_iterator d = descriptions.begin();
-    std::list<bool>::const_iterator        e = enableflags.begin();
-    for (std::list<std::string>::const_iterator o = overrides.begin(); o != overrides.end(); ++o, ++n, ++d, ++e)
+    std::list<std::string> overrides = oneFactory->GetClassOverrideNames();
+    std::list<std::string> names = oneFactory->GetClassOverrideWithNames();
+    std::list<std::string> descriptions = oneFactory->GetClassOverrideDescriptions();
+    std::list<bool>        enableflags = oneFactory->GetEnableFlags();
+    auto                   n = names.begin();
+    auto                   d = descriptions.begin();
+    auto                   e = enableflags.begin();
+    for (auto o = overrides.begin(); o != overrides.end(); ++o, ++n, ++d, ++e)
     {
       std::cout << "    Override " << *o << " with " << *n << std::endl
                 << "      described as \"" << *d << '"' << std::endl

Modules/Core/Common/test/itkObjectFactoryTest.cxx

@@ -158,14 +158,14 @@ itkObjectFactoryTest(int, char *[])
     std::cout << "  Factory version: " << oneFactory->GetITKSourceVersion() << std::endl
               << "  Factory description: " << oneFactory->GetDescription() << std::endl;
 
-    std::list<std::string>                 overrides = oneFactory->GetClassOverrideNames();
-    std::list<std::string>                 names = oneFactory->GetClassOverrideWithNames();
-    std::list<std::string>                 descriptions = oneFactory->GetClassOverrideDescriptions();
-    std::list<bool>                        enableflags = oneFactory->GetEnableFlags();
-    std::list<std::string>::const_iterator n = names.begin();
-    std::list<std::string>::const_iterator d = descriptions.begin();
-    std::list<bool>::const_iterator        e = enableflags.begin();
-    for (std::list<std::string>::const_iterator o = overrides.begin(); o != overrides.end(); ++o, ++n, ++d, ++e)
+    std::list<std::string> overrides = oneFactory->GetClassOverrideNames();
+    std::list<std::string> names = oneFactory->GetClassOverrideWithNames();
+    std::list<std::string> descriptions = oneFactory->GetClassOverrideDescriptions();
+    std::list<bool>        enableflags = oneFactory->GetEnableFlags();
+    auto                   n = names.begin();
+    auto                   d = descriptions.begin();
+    auto                   e = enableflags.begin();
+    for (auto o = overrides.begin(); o != overrides.end(); ++o, ++n, ++d, ++e)
     {
       std::cout << "    Override " << *o << " with " << *n << std::endl
                 << "      described as \"" << *d << '"' << std::endl

Modules/Core/Common/test/itkObjectFactoryTest2.cxx

@@ -142,14 +142,14 @@ itkObjectFactoryTest2(int argc, char * argv[])
       std::cout << "  Factory version: " << factory->GetITKSourceVersion() << std::endl
                 << "  Factory description: " << factory->GetDescription() << std::endl;
 
-      std::list<std::string>                 overrides = factory->GetClassOverrideNames();
-      std::list<std::string>                 names = factory->GetClassOverrideWithNames();
-      std::list<std::string>                 descriptions = factory->GetClassOverrideDescriptions();
-      std::list<bool>                        enableflags = factory->GetEnableFlags();
-      std::list<std::string>::const_iterator n = names.begin();
-      std::list<std::string>::const_iterator d = descriptions.begin();
-      std::list<bool>::const_iterator        e = enableflags.begin();
-      for (std::list<std::string>::const_iterator o = overrides.begin(); o != overrides.end(); ++o, ++n, ++d, ++e)
+      std::list<std::string> overrides = factory->GetClassOverrideNames();
+      std::list<std::string> names = factory->GetClassOverrideWithNames();
+      std::list<std::string> descriptions = factory->GetClassOverrideDescriptions();
+      std::list<bool>        enableflags = factory->GetEnableFlags();
+      auto                   n = names.begin();
+      auto                   d = descriptions.begin();
+      auto                   e = enableflags.begin();
+      for (auto o = overrides.begin(); o != overrides.end(); ++o, ++n, ++d, ++e)
       {
         std::cout << "    Override " << *o << " with " << *n << std::endl
                   << "      described as \"" << *d << '"' << std::endl

Modules/Core/Common/test/itkPriorityQueueTest.cxx

@@ -50,8 +50,8 @@ itkPriorityQueueTest(int, char *[])
   sequence.push_back(1.);
   sequence.push_back(-1.);
 
-  std::list<double>::const_iterator it = sequence.begin();
-  size_t                            i = 0;
+  auto   it = sequence.begin();
+  size_t i = 0;
   for (; it != sequence.end(); ++it, ++i)
   {
     min_priority_queue->Push(MinPQElementType(i, *it));

Modules/Core/Common/test/itkSTLContainerAdaptorTest.cxx

@@ -68,7 +68,7 @@ itkSTLContainerAdaptorTest(int, char *[])
       targetRef.reserve(vectorSource.size());
       targetRef.assign(vectorSource.begin(), vectorSource.end());
 
-      STLVectorType::const_iterator      it = vectorSource.begin();
+      auto                               it = vectorSource.begin();
       VectorContainerType::ConstIterator cIter = vectorContainer->Begin();
       while (it != vectorSource.end() && cIter != vectorContainer->End())
       {
@@ -116,7 +116,7 @@ itkSTLContainerAdaptorTest(int, char *[])
       std::cout << "Testing reading assignment... ";
       destination.assign(constTargetRef.begin(), constTargetRef.end());
 
-      STLVectorType::const_iterator      it = destination.begin();
+      auto                               it = destination.begin();
       VectorContainerType::ConstIterator cIter = vectorContainer->Begin();
       while (it != destination.end() && cIter != vectorContainer->End())
       {
@@ -193,7 +193,7 @@ itkSTLContainerAdaptorTest(int, char *[])
         targetRef[i] = mapSource[i];
       }
 
-      STLMapType::const_iterator      it = mapSource.begin();
+      auto                            it = mapSource.begin();
       MapContainerType::ConstIterator cIter = mapContainer->Begin();
       while (it != mapSource.end() && cIter != mapContainer->End())
       {
@@ -244,7 +244,7 @@ itkSTLContainerAdaptorTest(int, char *[])
         destination[i] = constTargetRef.find(i)->second;
       }
 
-      STLMapType::const_iterator      it = destination.begin();
+      auto                            it = destination.begin();
       MapContainerType::ConstIterator cIter = mapContainer->Begin();
       while (it != destination.end() && cIter != mapContainer->End())
       {