Add ArrayHandleCast

vtkm/cont/ArrayHandleCast.h

@@ -0,0 +1,86 @@
+//=============================================================================
+//
+//  Copyright (c) Kitware, Inc.
+//  All rights reserved.
+//  See LICENSE.txt for details.
+//
+//  This software is distributed WITHOUT ANY WARRANTY; without even
+//  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+//  PURPOSE.  See the above copyright notice for more information.
+//
+//  Copyright 2015 Sandia Corporation.
+//  Copyright 2015 UT-Battelle, LLC.
+//  Copyright 2015 Los Alamos National Security.
+//
+//  Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
+//  the U.S. Government retains certain rights in this software.
+//  Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
+//  Laboratory (LANL), the U.S. Government retains certain rights in
+//  this software.
+//
+//=============================================================================
+#ifndef vtk_m_cont_ArrayHandleCast_h
+#define vtk_m_cont_ArrayHandleCast_h
+
+#include <vtkm/cont/ArrayHandleTransform.h>
+
+namespace vtkm {
+namespace cont {
+
+namespace internal {
+
+template<typename FromType, typename ToType>
+struct Cast
+{
+  VTKM_EXEC_CONT_EXPORT
+  ToType operator()(const FromType &val) const
+  {
+    return static_cast<ToType>(val);
+  }
+};
+
+} // namespace internal
+
+
+/// \brief Cast the values of an array to the specified type, on demand.
+///
+/// ArrayHandleCast is a specialization of ArrayHandleTransform. Given an ArrayHandle
+/// and a type, it creates a new handle that returns the elements of the array cast
+/// to the specified type.
+///
+template <typename ValueType, typename ArrayHandleType>
+class ArrayHandleCast :
+  public vtkm::cont::ArrayHandleTransform<
+    ValueType,
+    ArrayHandleType,
+    internal::Cast<typename ArrayHandleType::ValueType, ValueType> >
+{
+public:
+  typedef vtkm::cont::ArrayHandleTransform<
+    ValueType,
+    ArrayHandleType,
+    internal::Cast<typename ArrayHandleType::ValueType, ValueType> > SuperClass;
+
+  ArrayHandleCast() : SuperClass()
+  { }
+
+  ArrayHandleCast(const ArrayHandleType &handle)
+    : SuperClass(handle)
+  { }
+};
+
+/// make_ArrayHandleCast is convenience function to generate an
+/// ArrayHandleCast.
+///
+template <typename T, typename HandleType>
+VTKM_CONT_EXPORT
+ArrayHandleCast<T, HandleType> make_ArrayHandleCast(const HandleType &handle,
+                                                    const T&)
+{
+  return ArrayHandleCast<T, HandleType>(handle);
+}
+
+}
+} // namespace vtkm::cont
+
+#endif // vtk_m_cont_ArrayHandleCast_h

vtkm/cont/CMakeLists.txt

@@ -22,6 +22,7 @@ include_directories(${Boost_INCLUDE_DIRS})
 
 set(headers
   ArrayHandle.h
+  ArrayHandleCast.h
   ArrayHandleCompositeVector.h
   ArrayHandleConstant.h
   ArrayHandleCounting.h

vtkm/cont/testing/TestingFancyArrayHandles.h

@@ -23,6 +23,7 @@
 #define vtk_m_cont_testing_TestingFancyArrayHandles_h
 
 #include <vtkm/cont/ArrayHandle.h>
+#include <vtkm/cont/ArrayHandleCast.h>
 #include <vtkm/cont/ArrayHandleCompositeVector.h>
 #include <vtkm/cont/ArrayHandleConstant.h>
 #include <vtkm/cont/ArrayHandleCounting.h>
@@ -452,6 +453,34 @@ private:
     }
   };
 
+  struct TestCastAsInput
+  {
+    template<typename CastToType>
+    VTKM_CONT_EXPORT
+    void operator()(CastToType vtkmNotUsed(type)) const
+    {
+      typedef vtkm::cont::ArrayHandleCounting<vtkm::Int64> InputArrayType;
+
+      InputArrayType input(0, ARRAY_SIZE);
+      vtkm::cont::ArrayHandleCast<CastToType, InputArrayType> castArray =
+          vtkm::cont::make_ArrayHandleCast(input, CastToType());
+      vtkm::cont::ArrayHandle<CastToType> result;
+
+      vtkm::worklet::DispatcherMapField< PassThrough, DeviceAdapterTag > dispatcher;
+      dispatcher.Invoke(castArray, result);
+
+      // verify results
+      vtkm::Id length = ARRAY_SIZE;
+      for (vtkm::Id i = 0; i < length; ++i)
+      {
+        VTKM_TEST_ASSERT(
+            result.GetPortalConstControl().Get(i) ==
+              static_cast<CastToType>(input.GetPortalConstControl().Get(i)),
+            "Casting ArrayHandle Failed");
+      }
+    }
+  };
+
 
   struct TestZipAsInput
   {
@@ -617,6 +646,12 @@ private:
                          >
   {  };
 
+  struct CastTypesToTest
+    : vtkm::ListTagBase< vtkm::Int32,
+                         vtkm::UInt32
+                       >
+  { };
+
 
   struct TestAll
   {
@@ -666,6 +701,12 @@ private:
                               TestingFancyArrayHandles<DeviceAdapterTag>::TestCountingTransformAsInput(),
                               HandleTypesToTest());
 
+      std::cout << "-------------------------------------------" << std::endl;
+      std::cout << "Testing ArrayHandleCast as Input" << std::endl;
+      vtkm::testing::Testing::TryTypes(
+                              TestingFancyArrayHandles<DeviceAdapterTag>::TestCastAsInput(),
+                              CastTypesToTest());
+
       std::cout << "-------------------------------------------" << std::endl;
       std::cout << "Testing ArrayHandleZip as Input" << std::endl;
       vtkm::testing::Testing::TryTypes(