Add ArrayHandleConstant

vtkm/cont/ArrayHandleConstant.h

+//=============================================================================
+//
+//  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_ArrayHandleConstant_h
+#define vtk_m_cont_ArrayHandleConstant_h
+
+#include <vtkm/cont/ArrayHandleImplicit.h>
+
+namespace vtkm {
+namespace cont {
+
+namespace detail {
+
+template<typename ValueType>
+struct ConstantFunctor
+{
+  VTKM_EXEC_CONT_EXPORT
+  ConstantFunctor(const ValueType &value = ValueType()) : Value(value) {  }
+
+  VTKM_EXEC_CONT_EXPORT
+  ValueType operator()(vtkm::Id vtkmNotUsed(index)) const
+  {
+    return this->Value;
+  }
+
+private:
+  ValueType Value;
+};
+
+} // namespace detail
+
+/// \brief An array handle with a constant value.
+///
+/// ArrayHandleConstant is an implicit array handle with a constant value. A
+/// constant array handle is constructed by giving a value and an array length.
+/// The resulting array is of the given size with each entry the same value
+/// given in the constructor. The array is defined implicitly, so there it
+/// takes (almost) no memory.
+///
+template<typename T>
+class ArrayHandleConstant
+    : public vtkm::cont::ArrayHandleImplicit<T, detail::ConstantFunctor<T> >
+{
+  typedef vtkm::cont::ArrayHandleImplicit<T, detail::ConstantFunctor<T> >
+      Superclass;
+
+public:
+  VTKM_CONT_EXPORT
+  ArrayHandleConstant(T value = T(), vtkm::Id numberOfValues = 0)
+    : Superclass(detail::ConstantFunctor<T>(value), numberOfValues) {  }
+};
+
+/// make_ArrayHandleImplicit is convenience function to generate an
+/// ArrayHandleImplicit.  It takes a functor and the virtual length of the
+/// arry.
+///
+template<typename T>
+vtkm::cont::ArrayHandleConstant<T>
+make_ArrayHandleConstant(T value, vtkm::Id numberOfValues)
+{
+  return vtkm::cont::ArrayHandleConstant<T>(value, numberOfValues);
+}
+
+}
+} // vtkm::cont
+
+#endif //vtk_m_cont_ArrayHandleConstant_h

vtkm/cont/ArrayHandleCounting.h

@@ -96,7 +96,7 @@ struct ArrayHandleCountingTraits
 
 } // namespace internal
 
-/// ArrayHandleCountings is a specialization of ArrayHandle. By default it
+/// ArrayHandleCounting is a specialization of ArrayHandle. By default it
 /// contains a increment value, that is increment for each step between zero
 /// and the passed in length
 template <typename CountingValueType>

vtkm/cont/CMakeLists.txt

@@ -23,6 +23,7 @@ include_directories(${Boost_INCLUDE_DIRS})
 set(headers
   ArrayHandle.h
   ArrayHandleCompositeVector.h
+  ArrayHandleConstant.h
   ArrayHandleCounting.h
   ArrayHandleImplicit.h
   ArrayHandlePermutation.h

vtkm/cont/testing/TestingFancyArrayHandles.h

@@ -22,6 +22,7 @@
 #ifndef vtk_m_cont_testing_TestingFancyArrayHandles_h
 #define vtk_m_cont_testing_TestingFancyArrayHandles_h
 
+#include <vtkm/cont/ArrayHandleConstant.h>
 #include <vtkm/cont/ArrayHandleCounting.h>
 #include <vtkm/cont/ArrayHandleImplicit.h>
 #include <vtkm/cont/ArrayHandlePermutation.h>
@@ -252,6 +253,33 @@ private:
     }
   };
 
+  struct TestConstantAsInput
+  {
+    template< typename ValueType >
+    VTKM_CONT_EXPORT void operator()(const ValueType vtkmNotUsed(v)) const
+    {
+      const ValueType value = TestValue(43, ValueType());
+
+      vtkm::cont::ArrayHandleConstant<ValueType> constant =
+          vtkm::cont::make_ArrayHandleConstant(value, ARRAY_SIZE);
+      vtkm::cont::ArrayHandle<ValueType> result;
+
+      vtkm::worklet::DispatcherMapField<PassThrough, DeviceAdapterTag> dispatcher;
+      dispatcher.Invoke(constant, result);
+
+      //verify that the control portal works
+      for(vtkm::Id i=0; i < ARRAY_SIZE; ++i)
+        {
+        const ValueType result_v = result.GetPortalConstControl().Get(i);
+        const ValueType control_value = constant.GetPortalConstControl().Get(i);
+        VTKM_TEST_ASSERT(test_equal(result_v, value),
+                         "Counting Handle Failed");
+        VTKM_TEST_ASSERT(test_equal(result_v, control_value),
+                         "Counting Handle Control Failed");
+        }
+    }
+  };
+
   struct TestCountingAsInput
   {
     template< typename ValueType >
@@ -556,6 +584,12 @@ struct TestPermutationAsOutput
                               TestingFancyArrayHandles<DeviceAdapterTag>::TestZipAsInput(),
                               ZipTypesToTest());
 
+      std::cout << "-------------------------------------------" << std::endl;
+      std::cout << "Testing ArrayHandleConstant as Input" << std::endl;
+      vtkm::testing::Testing::TryTypes(
+                              TestingFancyArrayHandles<DeviceAdapterTag>::TestConstantAsInput(),
+                              HandleTypesToTest());
+
       std::cout << "-------------------------------------------" << std::endl;
       std::cout << "Testing ArrayHandleCounting as Input" << std::endl;
       vtkm::testing::Testing::TryTypes(