Update compute_form_data and FormData to use a proper class and remove cell and facet average from balance modifiers. (#469)

* Cell and facet averages is not terminal modifiers.

* Move form data creation into form data

* Mypy fixes ones typing has been activated

* Fix typehint

* Make some consistency  across Integral and IntegralData

* Fixes related to @schnellerhase's comments

Author: jorgensd

ufl/algorithms/apply_restrictions.py

@@ -19,6 +19,7 @@
 from ufl.corealg.map_dag import map_expr_dag
 from ufl.corealg.multifunction import MultiFunction
 from ufl.domain import Mesh, extract_unique_domain
+from ufl.integral import Integral
 from ufl.sobolevspace import H1
 
 default_restriction_map = {
@@ -291,7 +292,9 @@ def facet_normal(self, o):
             return self._require_restriction(o)
 
 
-def apply_restrictions(expression: Expr, default_restrictions: dict | None = None) -> Expr:
+def apply_restrictions(
+    expression: Expr | Integral, default_restrictions: dict | None = None
+) -> Expr:
     """Propagate restriction nodes to wrap differential terminals directly.
 
     Args:

ufl/algorithms/balancing.py

@@ -7,8 +7,6 @@
 # SPDX-License-Identifier:    LGPL-3.0-or-later
 
 from ufl.classes import (
-    CellAvg,
-    FacetAvg,
     Grad,
     Indexed,
     NegativeRestricted,
@@ -26,8 +24,6 @@
             ReferenceValue,
             ReferenceGrad,
             Grad,
-            CellAvg,
-            FacetAvg,
             PositiveRestricted,
             NegativeRestricted,
             Indexed,
@@ -40,7 +36,6 @@ def balance_modified_terminal(expr):
     """Balance modified terminal."""
     # NB! Assuming e.g. grad(cell_avg(expr)) does not occur,
     # i.e. it is simplified to 0 immediately.
-
     if expr._ufl_is_terminal_:
         return expr
 
@@ -85,8 +80,6 @@ def _modifier(self, expr, *ops):
     reference_value = _modifier
     reference_grad = _modifier
     grad = _modifier
-    cell_avg = _modifier
-    facet_avg = _modifier
     positive_restricted = _modifier
     negative_restricted = _modifier