Opencl datahandling

Since the target_dh_refactoring was never merged, we decided to do the refactoring at smaller steps and recover the original OpenCL datahandling PR.

Refactoring to merge target and backend can be done later.

pystencils/field.py

@@ -15,7 +15,8 @@ import pystencils
 from pystencils.alignedarray import aligned_empty
 from pystencils.data_types import StructType, TypedSymbol, create_type
 from pystencils.kernelparameters import FieldShapeSymbol, FieldStrideSymbol
-from pystencils.stencil import direction_string_to_offset, offset_to_direction_string, inverse_direction
+from pystencils.stencil import (
+    direction_string_to_offset, inverse_direction, offset_to_direction_string)
 from pystencils.sympyextensions import is_integer_sequence
 
 __all__ = ['Field', 'fields', 'FieldType', 'AbstractField']
@@ -613,7 +614,10 @@ class Field(AbstractField):
 
     @property
     def physical_coordinates(self):
-        return self.coordinate_transform @ (self.coordinate_origin + pystencils.x_vector(self.spatial_dimensions))
+        if hasattr(self.coordinate_transform, '__call__'):
+            return self.coordinate_transform(self.coordinate_origin + pystencils.x_vector(self.spatial_dimensions))
+        else:
+            return self.coordinate_transform @ (self.coordinate_origin + pystencils.x_vector(self.spatial_dimensions))
 
     @property
     def physical_coordinates_staggered(self):