`vtkm::cont::UnknownArrayHandle` now provides a set of method that
allows you to copy data from one `UnknownArrayHandle` to another. The
first method, `DeepCopyFrom`, takes a source `UnknownArrayHandle` and
deep copies the data to the called one. If the `UnknownArrayHandle`
already points to a real `ArrayHandle`, the data is copied into that
`ArrayHandle`. If the `UnknownArrayHandle` does not point to an existing
`ArrayHandle`, then a new `ArrayHandleBasic` with the same value type as
the source is created and copied into.
The second method, `CopyShallowIfPossibleFrom` behaves similarly to
`DeepCopyFrom` except that it will perform a shallow copy if possible.
That is, if the target `UnknownArrayHandle` points to an `ArrayHandle`
of the same type as the source `UnknownArrayHandle`, then a shallow copy
occurs and the underlying `ArrayHandle` will point to the source. If the
types differ, then a deep copy is performed. If the target
`UnknownArrayHandle` does not point to an `ArrayHandle`, then the
behavior is the same as the `=` operator.
One of the intentions of these new methods is to allow you to copy
arrays without using a device compiler (e.g. `nvcc`). Calling
`ArrayCopy` requires you to include the `ArrayCopy.h` header file, and
that in turn requires device adapter algorithms. These methods insulate
you from these.
In VTK-m we have a constant tension between minimizing the number of
types we have to compile for (to reduce compile times and library size)
and maximizing the number of types that our filters support.
Unfortunately, if you don't compile a filter for a specific array type
(value type and storage), trying to run that filter will simply fail.
To compromise between the two, added methods to `DataSet` and `Field`
that will automatically convert the data in the `Field` arrays to a type
that VTK-m will understand. Although this will cause an extra data copy,
it will at least prevent the program from failing, and thus make it more
feasible to reduce types.
Added features with reporting types with `UnknownArrayHandle`. First,
added a method named `GetArrayTypeName` that returns a string containing
the type of the contained array. There were already methods
`GetValueType` and `GetStorageType`, but this provides a convenience to
get the whole name in one go.
Also improved the reporting when an `AsArrayHandle` call failed. Before,
the thrown method just reported that the `UnknownArrayHandle` could not
be converted to the given type. Now, it also reports the type actually
held by the `UnknownArrayHandle` so the user can better understand why
the conversion failed.
`UnknownArrayHandle` supported an `Allocate` method to change
the size of the underlying array without knowing its type.
However, it did not give all the features of `ArrayHandle`'s
allocate. Namely, you could not specify that the data should
be preserved and you could not provide a `Token` object. This
change adds these (optional) parameters.
This provides the ability to convert an array handle of an unknown value
type to an array handle that has `vtkm::FloatDefault` as its base
component type. Thus subsequently lets you pull the components as
`vtkm::FloatDefault` without having to worry about type conflicts.
The base C types have several "duplicate" types that the compiler
considers different even though the byte representation is the same. For
example, `char` and `signed char` have the same meaning but are treated
as different types. Likewise, 'long', 'int', and 'long long' are all
different types even though 'long' is the same as either 'int' or 'long
long'.
When pulling extracted components from `UnknownArrayHandle`, there is
little value for creating multiple code paths for types like `char` and
`signed char`. Instead, allow implicit conversion among these types.
The previous implementation of test_equal_ArrayHandles was several
templates that had to be resolved by any test that used them, which
could be costly for unknown array types. Simplify this a bit by moving
the implementation of testing unknown arrays into a library.
Another advantage of the new implementation is that is handles more
cases. Thus, you should not need to `ResetTypes` on the unknown/
uncertain arrays.
Previously, the `MapFieldMergeAverage` and `MapFieldPermutation` helper
function had to iterate over every possible type and create a separate
code path. This change uses the new extract component functionality to
create separate code paths only for different component types. This both
requires less code (the common filter library dropped from 66MB to 42MB
on my Mac) and covers more cases (such as `Vec`s larger than 4
components).
To make the implementation easier, `UnknownArrayHandle` now can create a
new `UnknownArrayHandle` of the same `ValueType` but with the basic
storage (so you can work with read-only storage) and the ability to
allocate the unknown array.
This allows you to handle just about every type of array with about 10
basic types. It allows you to ignore both the size of `Vec`s and the
actual storage of the data.
