ENH: Add stream insertion operators for std::list and C-style arrays

Modules/Core/Common/include/itkNeighborhood.hxx

@@ -19,6 +19,7 @@
 #define itkNeighborhood_hxx
 
 #include "itkNumericTraits.h"
+#include "itkPrintHelper.h"
 
 namespace itk
 {
@@ -115,22 +116,11 @@ template <typename TPixel, unsigned int VDimension, typename TContainer>
 void
 Neighborhood<TPixel, VDimension, TContainer>::PrintSelf(std::ostream & os, Indent indent) const
 {
+  using namespace itk::print_helper;
   os << indent << "Size: " << static_cast<typename NumericTraits<SizeType>::PrintType>(m_Size) << std::endl;
   os << indent << "Radius: " << static_cast<typename NumericTraits<SizeType>::PrintType>(m_Radius) << std::endl;
-
-  os << indent << "StrideTable: [ ";
-  for (DimensionValueType i = 0; i < VDimension; ++i)
-  {
-    os << indent.GetNextIndent() << m_StrideTable[i] << ' ';
-  }
-  os << ']' << std::endl;
-
-  os << indent << "OffsetTable: [ ";
-  for (DimensionValueType i = 0; i < m_OffsetTable.size(); ++i)
-  {
-    os << indent.GetNextIndent() << m_OffsetTable[i] << ' ';
-  }
-  os << ']' << std::endl;
+  os << indent << "StrideTable: " << m_StrideTable << std::endl;
+  os << indent << "OffsetTable: " << m_OffsetTable << std::endl;
 }
 } // namespace itk
 

Modules/Core/Common/include/itkPrintHelper.h

@@ -21,6 +21,8 @@
 
 #include <iostream>
 #include <iterator>
+#include <list>
+#include <type_traits>
 
 // Workaround for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112467
 #if defined(ITK_WRAPPING_PARSER) && defined(__GNUC__) && !defined(__clang__)
@@ -41,13 +43,45 @@ std::ostream &
 operator<<(std::ostream & os, const std::vector<T> & v)
 {
   if (v.empty())
+  {
+    return os << "[]";
+  }
+
+  os << '[';
+  std::copy(v.begin(), v.end() - 1, std::ostream_iterator<T>(os, ", "));
+  return os << v.back() << ']';
+}
+
+template <typename T>
+std::ostream &
+operator<<(std::ostream & os, const std::list<T> & l)
+{
+  if (l.empty())
+  {
+    return os << "[]";
+  }
+
+  os << '[';
+  std::copy(l.begin(), std::prev(l.end()), std::ostream_iterator<T>(os, ", "));
+  return os << l.back() << ']';
+}
+
+// Stream insertion operator for C-style arrays, excluding character arrays (strings)
+template <typename T, size_t N, typename = std::enable_if_t<!std::is_same_v<T, char>>>
+std::ostream &
+operator<<(std::ostream & os, const T (&arr)[N])
+{
+  if constexpr (N == 0)
   {
     return os << "()";
   }
 
   os << '(';
-  std::copy(v.begin(), v.end() - 1, std::ostream_iterator<T>(os, ", "));
-  return os << v.back() << ')';
+  for (size_t i = 0; i < N - 1; ++i)
+  {
+    os << arr[i] << ", ";
+  }
+  return os << arr[N - 1] << ')';
 }
 
 } // namespace itk::print_helper

Modules/Core/Common/test/CMakeLists.txt

@@ -1895,6 +1895,7 @@ set(
   itkOptimizerParametersGTest.cxx
   itkPointGTest.cxx
   itkPointSetGTest.cxx
+  itkPrintHelperGTest.cxx
   itkRGBAPixelGTest.cxx
   itkRGBPixelGTest.cxx
   itkShapedImageNeighborhoodRangeGTest.cxx

Modules/Core/Common/test/itkPrintHelperGTest.cxx

@@ -0,0 +1,91 @@
+/*=========================================================================
+ *
+ *  Copyright NumFOCUS
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *         https://www.apache.org/licenses/LICENSE-2.0.txt
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *=========================================================================*/
+
+#include "itkPrintHelper.h"
+#include "itkOffset.h"
+#include "gtest/gtest.h"
+#include <sstream>
+#include <vector>
+#include <list>
+
+TEST(PrintHelper, Vector)
+{
+  using namespace itk::print_helper;
+  std::vector<int>   v{ 1, 2, 3, 4, 5 };
+  std::ostringstream oss;
+  oss << v;
+  EXPECT_EQ(oss.str(), "[1, 2, 3, 4, 5]");
+}
+
+TEST(PrintHelper, EmptyVector)
+{
+  using namespace itk::print_helper;
+  std::vector<int>   v;
+  std::ostringstream oss;
+  oss << v;
+  EXPECT_EQ(oss.str(), "[]");
+}
+
+TEST(PrintHelper, List)
+{
+  using namespace itk::print_helper;
+  std::list<int>     l{ 1, 2, 3, 4, 5 };
+  std::ostringstream oss;
+  oss << l;
+  EXPECT_EQ(oss.str(), "[1, 2, 3, 4, 5]");
+}
+
+TEST(PrintHelper, EmptyList)
+{
+  using namespace itk::print_helper;
+  std::list<int>     l;
+  std::ostringstream oss;
+  oss << l;
+  EXPECT_EQ(oss.str(), "[]");
+}
+
+TEST(PrintHelper, CStyleArray)
+{
+  using namespace itk::print_helper;
+  int                arr[5] = { 1, 2, 3, 4, 5 };
+  std::ostringstream oss;
+  oss << arr;
+  EXPECT_EQ(oss.str(), "(1, 2, 3, 4, 5)");
+}
+
+TEST(PrintHelper, CStyleArraySingleElement)
+{
+  using namespace itk::print_helper;
+  int                arr[1] = { 42 };
+  std::ostringstream oss;
+  oss << arr;
+  EXPECT_EQ(oss.str(), "(42)");
+}
+
+TEST(PrintHelper, VectorOfOffsets)
+{
+  using namespace itk::print_helper;
+  std::vector<itk::Offset<2>> v;
+  itk::Offset<2>              o1{ { 1, 2 } };
+  itk::Offset<2>              o2{ { 3, 4 } };
+  v.push_back(o1);
+  v.push_back(o2);
+  std::ostringstream oss;
+  oss << v;
+  EXPECT_EQ(oss.str(), "[[1, 2], [3, 4]]");
+}

Modules/Core/Transform/include/itkScalableAffineTransform.hxx

@@ -20,6 +20,7 @@
 
 #include "itkMath.h"
 #include "itkNumericTraits.h"
+#include "itkPrintHelper.h"
 #include "vnl/algo/vnl_matrix_inverse.h"
 
 namespace itk
@@ -77,19 +78,10 @@ template <typename TParametersValueType, unsigned int VDimension>
 void
 ScalableAffineTransform<TParametersValueType, VDimension>::PrintSelf(std::ostream & os, Indent indent) const
 {
+  using namespace itk::print_helper;
   Superclass::PrintSelf(os, indent);
-  os << indent << "Scale : ";
-  for (unsigned int i = 0; i < VDimension; ++i)
-  {
-    os << m_Scale[i] << ' ';
-  }
-  os << std::endl;
-  os << indent << "MatrixScale : ";
-  for (unsigned int i = 0; i < VDimension; ++i)
-  {
-    os << m_MatrixScale[i] << ' ';
-  }
-  os << std::endl;
+  os << indent << "Scale: " << m_Scale << std::endl;
+  os << indent << "MatrixScale: " << m_MatrixScale << std::endl;
 }
 
 template <typename TParametersValueType, unsigned int VDimension>

Modules/Filtering/ImageFeature/include/itkHoughTransform2DCirclesImageFilter.hxx

@@ -23,6 +23,7 @@
 #include "itkGaussianDerivativeImageFunction.h"
 #include "itkMinimumMaximumImageCalculator.h"
 #include "itkMath.h"
+#include "itkPrintHelper.h"
 
 namespace itk
 {
@@ -282,6 +283,7 @@ void
 HoughTransform2DCirclesImageFilter<TInputPixelType, TOutputPixelType, TRadiusPixelType>::PrintSelf(std::ostream & os,
                                                                                                    Indent indent) const
 {
+  using namespace itk::print_helper;
   Superclass::PrintSelf(os, indent);
 
   os << indent << "Threshold: " << m_Threshold << std::endl;
@@ -297,15 +299,7 @@ HoughTransform2DCirclesImageFilter<TInputPixelType, TOutputPixelType, TRadiusPix
 
   itkPrintSelfObjectMacro(RadiusImage);
 
-  os << indent << "CirclesList: " << std::endl;
-  unsigned int i = 0;
-  auto         it = m_CirclesList.begin();
-  while (it != m_CirclesList.end())
-  {
-    os << indent << '[' << i << "]: " << *it << std::endl;
-    ++it;
-    ++i;
-  }
+  os << indent << "CirclesList: " << m_CirclesList << std::endl;
 
   os << indent << "OldModifiedTime: " << NumericTraits<ModifiedTimeType>::PrintType(m_OldModifiedTime) << std::endl;
 }

Modules/Filtering/ImageFeature/include/itkHoughTransform2DLinesImageFilter.hxx

@@ -23,6 +23,7 @@
 #include "itkMinimumMaximumImageCalculator.h"
 #include "itkCastImageFilter.h"
 #include "itkMath.h"
+#include "itkPrintHelper.h"
 
 namespace itk
 {
@@ -356,6 +357,7 @@ template <typename TInputPixelType, typename TOutputPixelType>
 void
 HoughTransform2DLinesImageFilter<TInputPixelType, TOutputPixelType>::PrintSelf(std::ostream & os, Indent indent) const
 {
+  using namespace itk::print_helper;
   Superclass::PrintSelf(os, indent);
 
   os << indent << "Threshold: " << m_Threshold << std::endl;
@@ -365,15 +367,7 @@ HoughTransform2DLinesImageFilter<TInputPixelType, TOutputPixelType>::PrintSelf(s
   os << indent << "Accumulator blur variance: " << m_Variance << std::endl;
   itkPrintSelfObjectMacro(SimplifyAccumulator);
 
-  os << indent << "LinesList: " << std::endl;
-  unsigned int i = 0;
-  auto         it = m_LinesList.begin();
-  while (it != m_LinesList.end())
-  {
-    os << indent << '[' << i << "]: " << *it << std::endl;
-    ++it;
-    ++i;
-  }
+  os << indent << "LinesList: " << m_LinesList << std::endl;
 
   os << indent << "OldModifiedTime: " << NumericTraits<ModifiedTimeType>::PrintType(m_OldModifiedTime) << std::endl;
 }