Merge topic 'unknownarray-variable-vec'

9b62c9ee Enable storing variable-sized Vecs in UnknownArrayHandle
Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: Robert Maynard <robert.maynard@kitware.com>
Merge-request: !2260

vtkm/cont/UnknownArrayHandle.h

@@ -51,10 +51,23 @@ static vtkm::Id UnknownAHNumberOfValues(void* mem)
   return arrayHandle->GetNumberOfValues();
 }
 
+template <typename T, typename StaticSize = typename vtkm::VecTraits<T>::IsSizeStatic>
+struct UnknownAHNumberOfComponentsImpl;
+template <typename T>
+struct UnknownAHNumberOfComponentsImpl<T, vtkm::VecTraitsTagSizeStatic>
+{
+  static constexpr vtkm::IdComponent Value = vtkm::VecTraits<T>::NUM_COMPONENTS;
+};
+template <typename T>
+struct UnknownAHNumberOfComponentsImpl<T, vtkm::VecTraitsTagSizeVariable>
+{
+  static constexpr vtkm::IdComponent Value = 0;
+};
+
 template <typename T>
 static vtkm::IdComponent UnknownAHNumberOfComponents()
 {
-  return vtkm::VecTraits<T>::NUM_COMPONENTS;
+  return UnknownAHNumberOfComponentsImpl<T>::Value;
 }
 
 template <typename T, typename S>
@@ -303,6 +316,8 @@ public:
   ///
   /// If the array holds `vtkm::Vec` objects, this will return the number of components
   /// in each value. If the array holds a basic C type (such as `float`), this will return 1.
+  /// If the array holds `Vec`-like objects that have the number of components that can vary
+  /// at runtime, this method will return 0 (because there is no consistent answer).
   ///
   VTKM_CONT vtkm::IdComponent GetNumberOfComponents() const
   {

vtkm/cont/testing/UnitTestUnknownArrayHandle.cxx

@@ -11,6 +11,12 @@
 #include <vtkm/cont/UncertainArrayHandle.h>
 #include <vtkm/cont/UnknownArrayHandle.h>
 
+#include <vtkm/cont/ArrayHandleCast.h>
+#include <vtkm/cont/ArrayHandleConstant.h>
+#include <vtkm/cont/ArrayHandleCounting.h>
+#include <vtkm/cont/ArrayHandleGroupVecVariable.h>
+#include <vtkm/cont/ArrayHandleMultiplexer.h>
+
 #include <vtkm/TypeTraits.h>
 
 #include <vtkm/cont/testing/Testing.h>
@@ -237,6 +243,25 @@ void CheckAsArrayHandle(const ArrayHandleType& array)
     ArrayHandleType retrievedArray = arrayUnknown2.AsArrayHandle<ArrayHandleType>();
     VTKM_TEST_ASSERT(array == retrievedArray);
   }
+
+  {
+    std::cout << "    Try adding arrays with variable amounts of components" << std::endl;
+    // There might be some limited functionality, but you should still be able
+    // to get arrays in and out.
+
+    // Note, this is a bad way to implement this array. You should something like
+    // ArrayHandleGroupVec instead.
+    using VariableVecArrayType =
+      vtkm::cont::ArrayHandleGroupVecVariable<ArrayHandleType,
+                                              vtkm::cont::ArrayHandleCounting<vtkm::Id>>;
+    VariableVecArrayType inArray = vtkm::cont::make_ArrayHandleGroupVecVariable(
+      array, vtkm::cont::make_ArrayHandleCounting<vtkm::Id>(0, 2, ARRAY_SIZE / 2 + 1));
+    VTKM_TEST_ASSERT(inArray.GetNumberOfValues() == ARRAY_SIZE / 2);
+    vtkm::cont::UnknownArrayHandle arrayUnknown2 = inArray;
+    VTKM_TEST_ASSERT(arrayUnknown2.IsType<VariableVecArrayType>());
+    VariableVecArrayType retrievedArray = arrayUnknown2.AsArrayHandle<VariableVecArrayType>();
+    VTKM_TEST_ASSERT(retrievedArray == inArray);
+  }
 }
 
 // A vtkm::Vec if NumComps > 1, otherwise a scalar