Add support for bidirectional array transforms.

Array transforms can now be created with an inverse functor, allowing for
casts back into the native array type. As a result, array transforms with
both a functor and inverse functor defined can perform read and write
operations. As an example, ArrayHandleCast now supports this operation. The
original implementation of ArrayHandleCast (i.e. read only) has been renamed
'ArrayHandleCastForInput'.

examples/clipping/Clipping.cxx

@@ -60,7 +60,7 @@ inline vtkm::cont::ArrayHandle<vtkm::Float32> LoadBinaryPointDataImpl(
   flipEndianness(&buffer[0], numPoints);
 
   vtkm::cont::DeviceAdapterAlgorithm<DeviceAdapter>::Copy(
-    vtkm::cont::make_ArrayHandleCast(vtkm::cont::make_ArrayHandle(buffer), vtkm::Float32()),
+    vtkm::cont::make_ArrayHandleCastForInput(vtkm::cont::make_ArrayHandle(buffer), vtkm::Float32()),
     result);
 
   return result;

vtkm/cont/ArrayHandleCast.h

@@ -50,6 +50,29 @@ struct Cast
 ///
 template <typename T, typename ArrayHandleType>
 class ArrayHandleCast :
+  public vtkm::cont::ArrayHandleTransform<
+    T,
+    ArrayHandleType,
+    internal::Cast<typename ArrayHandleType::ValueType, T>,
+    internal::Cast<T, typename ArrayHandleType::ValueType> >
+{
+public:
+  VTKM_ARRAY_HANDLE_SUBCLASS(
+    ArrayHandleCast,
+    (ArrayHandleCast<T, ArrayHandleType>),
+    (vtkm::cont::ArrayHandleTransform<
+     T,
+     ArrayHandleType,
+     internal::Cast<typename ArrayHandleType::ValueType, T>,
+     internal::Cast<T, typename ArrayHandleType::ValueType> >));
+
+  ArrayHandleCast(const ArrayHandleType &handle)
+    : Superclass(handle)
+  { }
+};
+
+template <typename T, typename ArrayHandleType>
+class ArrayHandleCastForInput :
   public vtkm::cont::ArrayHandleTransform<
     T,
     ArrayHandleType,
@@ -57,15 +80,15 @@ class ArrayHandleCast :
 {
 public:
   VTKM_ARRAY_HANDLE_SUBCLASS(
-      ArrayHandleCast,
-      (ArrayHandleCast<T, ArrayHandleType>),
+      ArrayHandleCastForInput,
+      (ArrayHandleCastForInput<T, ArrayHandleType>),
       (vtkm::cont::ArrayHandleTransform<
          T,
          ArrayHandleType,
          internal::Cast<typename ArrayHandleType::ValueType, T> >));
 
   VTKM_CONT_EXPORT
-  ArrayHandleCast(const ArrayHandleType &handle)
+  ArrayHandleCastForInput(const ArrayHandleType &handle)
     : Superclass(handle)
   { }
 };
@@ -81,6 +104,13 @@ ArrayHandleCast<T, HandleType> make_ArrayHandleCast(const HandleType &handle,
   return ArrayHandleCast<T, HandleType>(handle);
 }
 
+template <typename T, typename HandleType>
+VTKM_CONT_EXPORT
+ArrayHandleCastForInput<T, HandleType> make_ArrayHandleCastForInput(const HandleType &handle,const T&)
+{
+  return ArrayHandleCastForInput<T, HandleType>(handle);
+}
+
 }
 } // namespace vtkm::cont
 

vtkm/cont/ArrayHandleTransform.h

@@ -27,20 +27,38 @@
 #include <vtkm/cont/ErrorControlBadType.h>
 #include <vtkm/cont/ErrorControlInternal.h>
 
+namespace vtkm {
+namespace cont {
+namespace internal {
+
+/// Tag used in place of an inverse functor.
+struct NullFunctorType {};
+
+}
+}
+} // namespace vtkm::cont::internal
+
 namespace vtkm {
 namespace exec {
 namespace internal {
+
+typedef vtkm::cont::internal::NullFunctorType NullFunctorType;
+
 /// \brief An array portal that transforms a value from another portal.
 ///
+template<typename ValueType_, typename PortalType_, typename FunctorType_,
+  typename InverseFunctorType_=NullFunctorType>
+class ArrayPortalExecTransform;
+
 template<typename ValueType_, typename PortalType_, typename FunctorType_>
-class ArrayPortalExecTransform
+class ArrayPortalExecTransform<ValueType_,PortalType_,FunctorType_,NullFunctorType>
 {
 public:
   typedef PortalType_ PortalType;
   typedef ValueType_ ValueType;
   typedef FunctorType_ FunctorType;
 
-  VTKM_CONT_EXPORT
+  VTKM_EXEC_CONT_EXPORT
   ArrayPortalExecTransform(const PortalType &portal = PortalType(),
                        const FunctorType &functor = FunctorType())
     : Portal(portal), Functor(functor)
@@ -51,7 +69,7 @@ public:
   /// type casting that the iterators do (like the non-const to const cast).
   ///
   template<class OtherV, class OtherP, class OtherF>
-  VTKM_CONT_EXPORT
+  VTKM_EXEC_CONT_EXPORT
   ArrayPortalExecTransform(const ArrayPortalExecTransform<OtherV,OtherP,OtherF> &src)
     : Portal(src.GetPortal()),
       Functor(src.GetFunctor())
@@ -73,11 +91,49 @@ public:
   VTKM_EXEC_CONT_EXPORT
   const FunctorType &GetFunctor() const { return this->Functor; }
 
-private:
+protected:
   PortalType Portal;
   FunctorType Functor;
 };
 
+template<typename ValueType_, typename PortalType_,
+  typename FunctorType_, typename InverseFunctorType_>
+class ArrayPortalExecTransform : public ArrayPortalExecTransform<ValueType_,PortalType_,FunctorType_,NullFunctorType>
+{
+public:
+  typedef ArrayPortalExecTransform<ValueType_,PortalType_,FunctorType_,NullFunctorType> Superclass;
+  typedef PortalType_ PortalType;
+  typedef ValueType_ ValueType;
+  typedef FunctorType_ FunctorType;
+  typedef InverseFunctorType_ InverseFunctorType;
+
+  VTKM_EXEC_CONT_EXPORT
+  ArrayPortalExecTransform(const PortalType &portal = PortalType(),
+                           const FunctorType &functor = FunctorType(),
+                const InverseFunctorType& inverseFunctor = InverseFunctorType())
+    : Superclass(portal,functor), InverseFunctor(inverseFunctor)
+  {  }
+
+  template<class OtherV, class OtherP, class OtherF, class OtherInvF>
+  VTKM_EXEC_CONT_EXPORT
+  ArrayPortalExecTransform(const ArrayPortalExecTransform<OtherV,OtherP,OtherF,OtherInvF> &src)
+    : Superclass(src), InverseFunctor(src.GetInverseFunctor())
+  {  }
+
+  VTKM_EXEC_EXPORT
+  void Set(vtkm::Id index, const ValueType& value) const {
+    return this->Portal.Set(index,this->InverseFunctor(value));
+  }
+
+  VTKM_EXEC_CONT_EXPORT
+  const InverseFunctorType &GetInverseFunctor() const {
+    return this->InverseFunctor; }
+
+private:
+  InverseFunctorType InverseFunctor;
+
+};
+
 }
 }
 } // namespace vtkm::exec::internal
@@ -90,8 +146,12 @@ namespace internal {
 
 /// \brief An array portal that transforms a value from another portal.
 ///
+template<typename ValueType_, typename PortalType_, typename FunctorType_,
+  typename InverseFunctorType=NullFunctorType>
+class ArrayPortalContTransform;
+
 template<typename ValueType_, typename PortalType_, typename FunctorType_>
-class ArrayPortalContTransform
+class ArrayPortalContTransform<ValueType_,PortalType_,FunctorType_,NullFunctorType>
 {
 public:
   typedef PortalType_ PortalType;
@@ -131,16 +191,53 @@ public:
   VTKM_CONT_EXPORT
   const FunctorType &GetFunctor() const { return this->Functor; }
 
-private:
+protected:
   PortalType Portal;
   FunctorType Functor;
 };
 
-template<typename ValueType, typename ArrayHandleType, typename FunctorType>
-struct StorageTagTransform {  };
+template<typename ValueType_, typename PortalType_, typename FunctorType_,
+  typename InverseFunctorType_>
+class ArrayPortalContTransform : public ArrayPortalContTransform<ValueType_,PortalType_,FunctorType_,NullFunctorType>
+{
+public:
+  typedef ArrayPortalContTransform<ValueType_,PortalType_,FunctorType_,NullFunctorType> Superclass;
+  typedef PortalType_ PortalType;
+  typedef ValueType_ ValueType;
+  typedef FunctorType_ FunctorType;
+  typedef InverseFunctorType_ InverseFunctorType;
+
+  VTKM_CONT_EXPORT
+  ArrayPortalContTransform(const PortalType &portal = PortalType(),
+                           const FunctorType &functor = FunctorType(),
+                           const InverseFunctorType &inverseFunctor = InverseFunctorType())
+    : Superclass(portal,functor), InverseFunctor(inverseFunctor)
+  {  }
+
+  template<class OtherV, class OtherP, class OtherF, class OtherInvF>
+  VTKM_CONT_EXPORT
+  ArrayPortalContTransform(const ArrayPortalContTransform<OtherV,OtherP,OtherF,OtherInvF> &src)
+    : Superclass(src), InverseFunctor(src.GetInverseFunctor())
+  {  }
+
+  VTKM_CONT_EXPORT
+  void Set(vtkm::Id index, const ValueType& value) const {
+    this->Portal.Set(index,this->InverseFunctor(value));
+  }
+
+  VTKM_CONT_EXPORT
+  const InverseFunctorType &GetInverseFunctor() const { return this->InverseFunctor; }
+
+private:
+  InverseFunctorType InverseFunctor;
+};
+
+template<typename ValueType, typename ArrayHandleType, typename FunctorType,
+  typename InverseFunctorType=NullFunctorType>
+struct StorageTagTransform {};
 
 template<typename T, typename ArrayHandleType, typename FunctorType>
-class Storage<T, StorageTagTransform<T, ArrayHandleType, FunctorType > >
+class Storage<T, StorageTagTransform<T, ArrayHandleType, FunctorType, NullFunctorType > >
 {
 public:
   typedef T ValueType;
@@ -221,6 +318,92 @@ private:
   bool Valid;
 };
 
+template<typename T, typename ArrayHandleType, typename FunctorType,
+  typename InverseFunctorType>
+class Storage<T,
+  StorageTagTransform<T, ArrayHandleType, FunctorType, InverseFunctorType> >
+{
+public:
+  typedef T ValueType;
+
+  typedef ArrayPortalContTransform<ValueType,
+    typename ArrayHandleType::PortalControl, FunctorType, InverseFunctorType>
+    PortalType;
+  typedef ArrayPortalContTransform<ValueType,
+    typename ArrayHandleType::PortalConstControl,FunctorType,InverseFunctorType>
+    PortalConstType;
+
+  VTKM_CONT_EXPORT
+  Storage() : Valid(false) {  }
+
+  VTKM_CONT_EXPORT
+  Storage(const ArrayHandleType &array,
+          const FunctorType &functor,
+          const InverseFunctorType &inverseFunctor)
+    : Array(array), Functor(functor), InverseFunctor(inverseFunctor), Valid(true) {  }
+
+  VTKM_CONT_EXPORT
+  PortalType GetPortal() {
+    VTKM_ASSERT_CONT(this->Valid);
+    return PortalType(this->Array.GetPortalControl(),
+                      this->Functor,
+                      this->InverseFunctor);
+  }
+
+  VTKM_CONT_EXPORT
+  PortalConstType GetPortalConst() const {
+    VTKM_ASSERT_CONT(this->Valid);
+    return PortalConstType(this->Array.GetPortalConstControl(),
+                           this->Functor,
+                           this->InverseFunctor);
+  }
+
+  VTKM_CONT_EXPORT
+  vtkm::Id GetNumberOfValues() const {
+    VTKM_ASSERT_CONT(this->Valid);
+    return this->Array.GetNumberOfValues();
+  }
+
+  VTKM_CONT_EXPORT
+  void Allocate(vtkm::Id numberOfValues) {
+    this->Array.Allocate(numberOfValues);
+    this->Valid = true;
+  }
+
+  VTKM_CONT_EXPORT
+  void Shrink(vtkm::Id numberOfValues) {
+    this->Array.Shrink(numberOfValues);
+  }
+
+  VTKM_CONT_EXPORT
+  void ReleaseResources() {
+    this->Array.ReleaseResources();
+    this->Valid = false;
+  }
+
+  VTKM_CONT_EXPORT
+  const ArrayHandleType &GetArray() const {
+    VTKM_ASSERT_CONT(this->Valid);
+    return this->Array;
+  }
+
+  VTKM_CONT_EXPORT
+  const FunctorType &GetFunctor() const {
+    return this->Functor;
+  }
+
+  VTKM_CONT_EXPORT
+  const InverseFunctorType &GetInverseFunctor() const {
+    return this->InverseFunctor;
+  }
+
+private:
+  ArrayHandleType Array;
+  FunctorType Functor;
+  InverseFunctorType InverseFunctor;
+  bool Valid;
+};
+
 template<typename T,
          typename ArrayHandleType,
          typename FunctorType,
@@ -295,6 +478,83 @@ private:
   FunctorType Functor;
 };
 
+template<typename T,
+         typename ArrayHandleType,
+         typename FunctorType,
+         typename InverseFunctorType,
+         typename Device>
+class ArrayTransfer<
+  T, StorageTagTransform<T,ArrayHandleType,FunctorType,InverseFunctorType>,
+  Device>
+{
+  typedef StorageTagTransform<T,ArrayHandleType,
+                              FunctorType,InverseFunctorType> StorageTag;
+  typedef vtkm::cont::internal::Storage<T, StorageTag> StorageType;
+
+public:
+  typedef T ValueType;
+
+  typedef typename StorageType::PortalType PortalControl;
+  typedef typename StorageType::PortalConstType PortalConstControl;
+
+  typedef vtkm::exec::internal::ArrayPortalExecTransform<
+      ValueType,
+      typename ArrayHandleType::template ExecutionTypes<Device>::Portal,
+      FunctorType, InverseFunctorType> PortalExecution;
+  typedef vtkm::exec::internal::ArrayPortalExecTransform<
+      ValueType,
+      typename ArrayHandleType::template ExecutionTypes<Device>::PortalConst,
+      FunctorType, InverseFunctorType> PortalConstExecution;
+
+  VTKM_CONT_EXPORT
+  ArrayTransfer(StorageType *storage)
+    : Array(storage->GetArray()),
+      Functor(storage->GetFunctor()),
+      InverseFunctor(storage->GetInverseFunctor()) {  }
+
+  VTKM_CONT_EXPORT
+  vtkm::Id GetNumberOfValues() const {
+    return this->Array.GetNumberOfValues();
+  }
+
+  VTKM_CONT_EXPORT
+  PortalConstExecution PrepareForInput(bool vtkmNotUsed(updateData)) {
+    return PortalConstExecution(this->Array.PrepareForInput(Device()),this->Functor,this->InverseFunctor);
+  }
+
+  VTKM_CONT_EXPORT
+  PortalExecution PrepareForInPlace(bool &vtkmNotUsed(updateData)) {
+    return PortalExecution(this->Array.PrepareForInPlace(Device()),this->Functor,this->InverseFunctor);
+  }
+
+  VTKM_CONT_EXPORT
+  PortalExecution PrepareForOutput(vtkm::Id numberOfValues) {
+    return PortalExecution(this->Array.PrepareForOutput(numberOfValues,
+                                                        Device()),this->Functor,this->InverseFunctor);
+  }
+
+  VTKM_CONT_EXPORT
+  void RetrieveOutputData(StorageType *vtkmNotUsed(storage)) const {
+    // Implementation of this method should be unnecessary. The internal
+    // array handle should automatically retrieve the output data as necessary.
+  }
+
+  VTKM_CONT_EXPORT
+  void Shrink(vtkm::Id numberOfValues) {
+    this->Array.Shrink(numberOfValues);
+  }
+
+  VTKM_CONT_EXPORT
+  void ReleaseResources() {
+    this->Array.ReleaseResourcesExecution();
+  }
+
+private:
+  ArrayHandleType Array;
+  FunctorType Functor;
+  InverseFunctorType InverseFunctor;
+};
+
 } // namespace internal
 
 /// \brief Implicitly transform values of one array to another with a functor.
@@ -308,10 +568,16 @@ private:
 /// the functor operator should work in both the control and execution
 /// environments.
 ///
+template <typename T,
+          typename ArrayHandleType,
+          typename FunctorType,
+          typename InverseFunctorType=internal::NullFunctorType>
+class ArrayHandleTransform;
+
 template <typename T,
           typename ArrayHandleType,
           typename FunctorType>
-class ArrayHandleTransform
+class ArrayHandleTransform<T,ArrayHandleType,FunctorType,internal::NullFunctorType>
     : public vtkm::cont::ArrayHandle<
         T, internal::StorageTagTransform<T, ArrayHandleType, FunctorType> >
 {
@@ -327,7 +593,7 @@ public:
          T, internal::StorageTagTransform<T, ArrayHandleType, FunctorType> >));
 
 private:
-  typedef vtkm::cont::internal::Storage<ValueType, StorageTag> StorageType;
+  typedef vtkm::cont::internal::Storage<T, StorageTag> StorageType;
 
 public:
   VTKM_CONT_EXPORT
@@ -348,6 +614,45 @@ make_ArrayHandleTransform(HandleType handle, FunctorType functor)
   return ArrayHandleTransform<T,HandleType,FunctorType>(handle,functor);
 }
 
+// ArrayHandleTransform with inverse functors enabled (no need to subclass from
+// ArrayHandleTransform without inverse functors: nothing to inherit).
+template <typename T,
+          typename ArrayHandleType,
+          typename FunctorType,
+          typename InverseFunctorType>
+class ArrayHandleTransform
+    : public vtkm::cont::ArrayHandle<
+        T,
+        internal::StorageTagTransform<T, ArrayHandleType, FunctorType,
+          InverseFunctorType> >
+{
+  VTKM_IS_ARRAY_HANDLE(ArrayHandleType);
+
+public:
+  VTKM_ARRAY_HANDLE_SUBCLASS(
+      ArrayHandleTransform,
+      (ArrayHandleTransform<T,ArrayHandleType,FunctorType,InverseFunctorType>),
+      (vtkm::cont::ArrayHandle<
+       T, internal::StorageTagTransform<T, ArrayHandleType, FunctorType,
+       InverseFunctorType> >));
+
+private:
+  typedef vtkm::cont::internal::Storage<T, StorageTag> StorageType;
+
+ public:
+  ArrayHandleTransform(const ArrayHandleType &handle,
+                       const FunctorType &functor = FunctorType(),
+                const InverseFunctorType &inverseFunctor = InverseFunctorType())
+    : Superclass(StorageType(handle, functor, inverseFunctor)) {  }
+};
+
+template <typename T, typename HandleType, typename FunctorType, typename InverseFunctorType>
+VTKM_CONT_EXPORT
+vtkm::cont::ArrayHandleTransform<T, HandleType, FunctorType, InverseFunctorType>
+make_ArrayHandleTransform(HandleType handle, FunctorType functor, InverseFunctorType inverseFunctor)
+{
+  return ArrayHandleTransform<T,HandleType,FunctorType,InverseFunctorType>(handle,functor,inverseFunctor);
+}
 
 }
 } // namespace vtkm::cont

vtkm/cont/internal/ConnectivityExplicitInternals.h

@@ -39,8 +39,8 @@ void buildIndexOffsets(const NumIndicesArrayType& numIndices,
 {
   //We first need to make sure that NumIndices and IndexOffsetArrayType
   //have the same type so we can call scane exclusive
-  typedef vtkm::cont::ArrayHandleCast< vtkm::Id,
-                                       NumIndicesArrayType > CastedNumIndicesType;
+  typedef vtkm::cont::ArrayHandleCastForInput< vtkm::Id,
+    NumIndicesArrayType > CastedNumIndicesType;
 
   // Although technically we are making changes to this object, the changes
   // are logically consistent with the previous state, so we consider it

vtkm/cont/testing/TestingFancyArrayHandles.h

@@ -421,8 +421,9 @@ private:
       typedef vtkm::cont::ArrayHandleIndex InputArrayType;
 
       InputArrayType input(ARRAY_SIZE);
-      vtkm::cont::ArrayHandleCast<CastToType, InputArrayType> castArray =
-          vtkm::cont::make_ArrayHandleCast(input, CastToType());
+      vtkm::cont::ArrayHandleCastForInput<CastToType,
+        InputArrayType> castArray =
+          vtkm::cont::make_ArrayHandleCastForInput(input, CastToType());
       vtkm::cont::ArrayHandle<CastToType> result;
 
       vtkm::worklet::DispatcherMapField< PassThrough, DeviceAdapterTag > dispatcher;