started with list lbm implementation

- extended pystencils
- Visualization for list LBM
- not yet working

transformations.py

@@ -2,6 +2,8 @@ import warnings
 from collections import defaultdict, OrderedDict, namedtuple
 from copy import deepcopy
 from types import MappingProxyType
+
+import itertools
 import sympy as sp
 from sympy.logic.boolalg import Boolean
 from sympy.tensor import IndexedBase
@@ -390,6 +392,12 @@ def resolve_field_accesses(ast_node, read_only_field_names=set(),
     def visit_sympy_expr(expr, enclosing_block, sympy_assignment):
         if isinstance(expr, Field.Access):
             field_access = expr
+
+            if any(isinstance(off, Field.Access) for off in field_access.offsets):
+                new_offsets = tuple(visit_sympy_expr(off, enclosing_block, sympy_assignment)
+                                    for off in field_access.offsets)
+                field_access = Field.Access(field_access.field, new_offsets, field_access.index)
+
             field = field_access.field
 
             if field.name in field_to_base_pointer_info:
@@ -711,6 +719,9 @@ class KernelConstraintsCheck:
         self._update_accesses_rhs(rhs)
         if isinstance(rhs, Field.Access):
             self.fields_read.add(rhs.field)
+            for e in itertools.chain(rhs.offsets, rhs.index):
+                if isinstance(e, sp.Basic):
+                    self.fields_read.update(access.field for access in e.atoms(Field.Access))
             return rhs
         elif isinstance(rhs, TypedSymbol):
             return rhs