STYLE: Use trailing return type instead of typename in "*.h" files

Did Notepad++ v8.4.8, Find in Files (Regular expression enabled):

    Find what: ^typename (\w+<.+>::)(.+)\r\n\1(.+)\r\n{\r\n
    Replace with: auto\r\n$1$3 -> $2\r\n{\r\n

    Find what: ^inline typename (\w+<.+>::)(.+)\r\n\1(.+)\r\n{\r\n
    Replace with: inline auto\r\n$1$3 -> $2\r\n{\r\n

Specifically for "itk*.h" files

In accordance with ITKSoftwareGuide pull request InsightSoftwareConsortium/ITKSoftwareGuide#162
commit InsightSoftwareConsortium/ITKSoftwareGuide@c64b23b
"ENH: Add "Trailing Return Types" section"

Follow-up to pull request #4026
commit f048a5b "STYLE: Use trailing return type
for declarations containing "inline""

Modules/Compatibility/Deprecated/include/itkInOrderTreeIterator.h

@@ -75,8 +75,8 @@ InOrderTreeIterator<TTreeType>::InOrderTreeIterator(TTreeType * tree, TreeNodeTy
 
 /** Get the type of the iterator */
 template <typename TTreeType>
-typename InOrderTreeIterator<TTreeType>::NodeType
-InOrderTreeIterator<TTreeType>::GetType() const
+auto
+InOrderTreeIterator<TTreeType>::GetType() const -> NodeType
 {
   return TreeIteratorBaseEnums::TreeIteratorBaseNode::INORDER;
 }

Modules/Compatibility/Deprecated/include/itkLeafTreeIterator.h

@@ -106,8 +106,8 @@ LeafTreeIterator<TTreeType>::~LeafTreeIterator() = default;
 
 /** Return the type of iterator */
 template <typename TTreeType>
-typename LeafTreeIterator<TTreeType>::NodeType
-LeafTreeIterator<TTreeType>::GetType() const
+auto
+LeafTreeIterator<TTreeType>::GetType() const -> NodeType
 {
   return TreeIteratorBaseEnums::TreeIteratorBaseNode::LEAF;
 }

Modules/Compatibility/Deprecated/include/itkPostOrderTreeIterator.h

@@ -89,8 +89,8 @@ PostOrderTreeIterator<TTreeType>::PostOrderTreeIterator(TTreeType * tree)
 
 /** Return the type of the iterator */
 template <typename TTreeType>
-typename PostOrderTreeIterator<TTreeType>::NodeType
-PostOrderTreeIterator<TTreeType>::GetType() const
+auto
+PostOrderTreeIterator<TTreeType>::GetType() const -> NodeType
 {
   return TreeIteratorBaseEnums::TreeIteratorBaseNode::POSTORDER;
 }

Modules/Compatibility/Deprecated/include/itkPreOrderTreeIterator.h

@@ -75,8 +75,8 @@ PreOrderTreeIterator<TTreeType>::PreOrderTreeIterator(const TTreeType * tree, co
 
 /** Return the type of the iterator */
 template <typename TTreeType>
-typename PreOrderTreeIterator<TTreeType>::NodeType
-PreOrderTreeIterator<TTreeType>::GetType() const
+auto
+PreOrderTreeIterator<TTreeType>::GetType() const -> NodeType
 {
   return TreeIteratorBaseEnums::TreeIteratorBaseNode::PREORDER;
 }

Modules/Compatibility/Deprecated/include/itkRootTreeIterator.h

@@ -74,8 +74,8 @@ RootTreeIterator<TTreeType>::RootTreeIterator(TTreeType * tree, const TreeNodeTy
 
 /** Return the type of the iterator */
 template <typename TTreeType>
-typename RootTreeIterator<TTreeType>::NodeType
-RootTreeIterator<TTreeType>::GetType() const
+auto
+RootTreeIterator<TTreeType>::GetType() const -> NodeType
 {
   return TreeIteratorBaseEnums::TreeIteratorBaseNode::ROOT;
 }

Modules/Core/Transform/include/itkTranslationTransform.h

@@ -257,32 +257,36 @@ class ITK_TEMPLATE_EXPORT TranslationTransform : public Transform<TParametersVal
 
 // Back transform a point
 template <typename TParametersValueType, unsigned int VDimension>
-inline typename TranslationTransform<TParametersValueType, VDimension>::InputPointType
+inline auto
 TranslationTransform<TParametersValueType, VDimension>::BackTransform(const OutputPointType & point) const
+  -> InputPointType
 {
   return point - m_Offset;
 }
 
 // Back transform a vector
 template <typename TParametersValueType, unsigned int VDimension>
-inline typename TranslationTransform<TParametersValueType, VDimension>::InputVectorType
+inline auto
 TranslationTransform<TParametersValueType, VDimension>::BackTransform(const OutputVectorType & vect) const
+  -> InputVectorType
 {
   return vect;
 }
 
 // Back transform a vnl_vector
 template <typename TParametersValueType, unsigned int VDimension>
-inline typename TranslationTransform<TParametersValueType, VDimension>::InputVnlVectorType
+inline auto
 TranslationTransform<TParametersValueType, VDimension>::BackTransform(const OutputVnlVectorType & vect) const
+  -> InputVnlVectorType
 {
   return vect;
 }
 
 // Back Transform a CovariantVector
 template <typename TParametersValueType, unsigned int VDimension>
-inline typename TranslationTransform<TParametersValueType, VDimension>::InputCovariantVectorType
+inline auto
 TranslationTransform<TParametersValueType, VDimension>::BackTransform(const OutputCovariantVectorType & vect) const
+  -> InputCovariantVectorType
 {
   return vect;
 }

Modules/Filtering/ImageIntensity/include/itkClampImageFilter.h

@@ -89,8 +89,8 @@ class ITK_TEMPLATE_EXPORT Clamp
 
 
 template <typename TInput, typename TOutput>
-inline typename Clamp<TInput, TOutput>::OutputType
-Clamp<TInput, TOutput>::operator()(const InputType & A) const
+inline auto
+Clamp<TInput, TOutput>::operator()(const InputType & A) const -> OutputType
 {
   const auto dA = static_cast<double>(A);
 

Modules/Numerics/FEM/include/itkFEMPArray.h

@@ -104,8 +104,8 @@ class FEMPArray : public std::vector<FEMP<T>>
  * Find function for for non-const objects
  */
 template <typename T>
-typename FEMPArray<T>::ClassTypePointer
-FEMPArray<T>::Find(int gn)
+auto
+FEMPArray<T>::Find(int gn) -> ClassTypePointer
 {
   auto it = this->begin();
   auto iend = this->end();
@@ -136,8 +136,8 @@ FEMPArray<T>::Find(int gn)
  * Find function for for const objects
  */
 template <typename T>
-typename FEMPArray<T>::ClassTypeConstPointer
-FEMPArray<T>::Find(int gn) const
+auto
+FEMPArray<T>::Find(int gn) const -> ClassTypeConstPointer
 {
   using ConstIterator = typename Superclass::const_iterator;