Allow creation of indexed kernels with opencl

pystencils/kernelcreation.py

-from itertools import combinations
+import functools
+import itertools
 from types import MappingProxyType
 
 import sympy as sp
@@ -12,7 +13,6 @@ from pystencils.simp.assignment_collection import AssignmentCollection
 from pystencils.stencil import direction_string_to_offset, inverse_direction_string
 from pystencils.transformations import (
     loop_blocking, move_constants_before_loop, remove_conditionals_in_staggered_kernel)
-import functools
 
 
 def create_kernel(assignments,
@@ -143,7 +143,9 @@ def create_indexed_kernel(assignments,
                           cpu_openmp=True,
                           gpu_indexing='block',
                           gpu_indexing_params=MappingProxyType({}),
-                          use_textures_for_interpolation=True):
+                          use_textures_for_interpolation=True,
+                          opencl_queue=None,
+                          opencl_ctx=None):
     """
     Similar to :func:`create_kernel`, but here not all cells of a field are updated but only cells with
     coordinates which are stored in an index field. This traversal method can e.g. be used for boundary handling.
@@ -193,7 +195,7 @@ def create_indexed_kernel(assignments,
         return ast
     elif target == 'llvm':
         raise NotImplementedError("Indexed kernels are not yet supported in LLVM backend")
-    elif target == 'gpu':
+    elif target == 'gpu' or target == 'opencl':
         from pystencils.gpucuda import created_indexed_cuda_kernel
         idx_creator = indexing_creator_from_params(gpu_indexing, gpu_indexing_params)
         ast = created_indexed_cuda_kernel(assignments,
@@ -202,6 +204,12 @@ def create_indexed_kernel(assignments,
                                           coordinate_names=coordinate_names,
                                           indexing_creator=idx_creator,
                                           use_textures_for_interpolation=use_textures_for_interpolation)
+        if target == 'opencl':
+            from pystencils.opencl.opencljit import make_python_function
+            ast._backend = 'opencl'
+            ast.compile = functools.partial(make_python_function, ast, opencl_queue, opencl_ctx)
+            ast._target = 'opencl'
+            ast._backend = 'opencl'
         return ast
     else:
         raise ValueError("Unknown target %s. Has to be either 'cpu' or 'gpu'" % (target,))
@@ -298,7 +306,7 @@ def create_staggered_kernel(assignments, target='cpu', gpu_exclusive_conditions=
         outer_assignment = None
         conditions = {direction: condition(direction) for direction in stencil}
         for num_conditions in range(len(stencil)):
-            for combination in combinations(conditions.values(), num_conditions):
+            for combination in itertools.combinations(conditions.values(), num_conditions):
                 for assignment in assignments:
                     direction = stencil[assignment.lhs.index[0]]
                     if conditions[direction] in combination: