From db803d3c173c919f55d0d183d33598176eedefc8 Mon Sep 17 00:00:00 2001
From: Julien Michel <julien.michel@cnes.fr>
Date: Fri, 16 Nov 2018 09:46:15 +0100
Subject: [PATCH] COMP: Fix static_asserts on pixel type detection

---
 .../Functor/include/otbFunctorImageFilter.h   | 50 ++++++++++++++-----
 .../Functor/test/otbFunctorImageFilter.cxx    |  5 +-
 2 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/Modules/Core/Functor/include/otbFunctorImageFilter.h b/Modules/Core/Functor/include/otbFunctorImageFilter.h
index 7e13f002ce..1a7daba4ec 100644
--- a/Modules/Core/Functor/include/otbFunctorImageFilter.h
+++ b/Modules/Core/Functor/include/otbFunctorImageFilter.h
@@ -32,7 +32,6 @@
 
 namespace otb
 {
-
 /**  
  * \struct IsNeighborhood 
  * \brief Struct testing if T is a neighborhood
@@ -73,22 +72,42 @@ template <class T> struct IsSuitableType
   static constexpr bool value = std::is_scalar<T>::value;
 };
 
+/// Unwrap complex
 template <class T> struct IsSuitableType<std::complex<T>> {
   static constexpr bool value = IsSuitableType<T>::value;
 };
+
+/// Unwrap VariableLengthVector
 template <class T> struct IsSuitableType<itk::VariableLengthVector<T>> {
   static constexpr bool value = IsSuitableType<T>::value;
 };
+
+/// Unwrap FixedArray
 template <class T> struct IsSuitableType<itk::FixedArray<T>> {
   static constexpr bool value = IsSuitableType<T>::value;
 };
+
+/// Unwrap RGBPixel
 template <class T> struct IsSuitableType<itk::RGBPixel<T>> {
   static constexpr bool value = IsSuitableType<T>::value;
 };
+
+/// Unwrap RGBAPixel
 template <class T> struct IsSuitableType<itk::RGBAPixel<T>> {
   static constexpr bool value = IsSuitableType<T>::value;
 };
 
+/// Discard const qualifier
+template <class T> struct IsSuitableType<const T>{
+  static constexpr bool value = IsSuitableType<T>::value;
+};
+
+/// Discard reference
+template <class T> struct IsSuitableType<T &>{
+  static constexpr bool value = IsSuitableType<T>::value;
+};
+
+
 /**
  * \struct PixelTypeDeduction
  * \brief Helper struct to derive PixelType from template parameter.
@@ -110,13 +129,20 @@ template <class T> struct PixelTypeDeduction<itk::Neighborhood<T>>
   using PixelType = T;
 };
 
-/// Partial specialisation for const itk::Neighborhood<T> &
-template <class T> struct PixelTypeDeduction<const itk::Neighborhood<T>&>
+/// Discard const qualifier
+template <class T> struct PixelTypeDeduction<const  T>
 {
-  static_assert(IsSuitableType<T>::value,"T can not be used as a template parameter for Image or VectorImage classes.");
-  using PixelType = T;
+  using PixelType = typename PixelTypeDeduction<T>::PixelType;
 };
 
+/// Discard reference
+template <class T> struct PixelTypeDeduction<T &>
+{
+  using PixelType = typename PixelTypeDeduction<T>::PixelType;
+};
+
+  
+
 /** 
  * \struct ImageTypeDeduction
  * \brief Helper struct to derive ImageType from template parameter
@@ -136,11 +162,11 @@ template <class T> struct ImageTypeDeduction<itk::VariableLengthVector<T>>
   using ImageType = otb::VectorImage<T>;
 };
 
-/// Partial specialisation for const T &
-template <class T> struct ImageTypeDeduction<const T &>
-{
-  using ImageType = typename ImageTypeDeduction<T>::ImageType;
-};
+// /// Partial specialisation for const T &
+// template <class T> struct ImageTypeDeduction<const T &>
+// {
+//   using ImageType = typename ImageTypeDeduction<T>::ImageType;
+// };
 
 
 /**
@@ -165,7 +191,7 @@ template <typename R, typename... T> struct FunctorFilterSuperclassHelper<R(*)(T
   using InputHasNeighborhood = std::tuple<typename IsNeighborhood<T>::ValueType...>;
 };
 
-// Partial specialisation for R(C::*)(T...) const
+/// Partial specialisation for R(C::*)(T...) const
 template <typename C, typename R, typename... T> struct FunctorFilterSuperclassHelper<R(C::*)(T...) const>
 {
   using OutputImageType = typename ImageTypeDeduction<R>::ImageType;
@@ -173,7 +199,7 @@ template <typename C, typename R, typename... T> struct FunctorFilterSuperclassH
   using InputHasNeighborhood = std::tuple<typename IsNeighborhood<T>::ValueType...>;
 };
 
-// Partial specialisation for R(C::*)(T...)
+/// Partial specialisation for R(C::*)(T...)
 template <typename C, typename R, typename... T> struct FunctorFilterSuperclassHelper<R(C::*)(T...)>
 { 
   using OutputImageType = typename ImageTypeDeduction<R>::ImageType;
diff --git a/Modules/Core/Functor/test/otbFunctorImageFilter.cxx b/Modules/Core/Functor/test/otbFunctorImageFilter.cxx
index e1cd5360e2..cf42cb22b5 100644
--- a/Modules/Core/Functor/test/otbFunctorImageFilter.cxx
+++ b/Modules/Core/Functor/test/otbFunctorImageFilter.cxx
@@ -62,8 +62,6 @@ template <typename T> struct TypesCheck
   // Test ImageTypeDeduction struct
   static_assert(std::is_same<typename ImageTypeDeduction<ScalarType>::ImageType,ImageType>::value,"");
   static_assert(std::is_same<typename ImageTypeDeduction<VectorType>::ImageType,VectorImageType>::value,"");
-  static_assert(std::is_same<typename ImageTypeDeduction<const ScalarType &>::ImageType,ImageType>::value,"");
-  static_assert(std::is_same<typename ImageTypeDeduction<const VectorType &>::ImageType,VectorImageType>::value,"");
 
   // Fake test operator
   template <typename TOut,typename TIn> struct TestOperator
@@ -120,7 +118,8 @@ template <typename T> struct TypesCheck
   } 
 };
 
-auto checksDouble = TypesCheck<double>{};
+auto checksInt     = TypesCheck<int>{};
+auto checksDouble  = TypesCheck<double>{};
 auto checksComplex = TypesCheck<std::complex<double>>{};
 
 // Example functors
-- 
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