Validate representation type items when leaving item mode.

src/ifcopenshell-python/ifcopenshell/api/geometry/__init__.py

@@ -62,6 +62,7 @@ from .map_representation import map_representation
 from .remove_boolean import remove_boolean
 from .remove_representation import remove_representation
 from .unassign_representation import unassign_representation
+from .validate_type import validate_type
 
 wrap_usecases(__path__, __name__)
 
@@ -88,4 +89,5 @@ __all__ = [
     "remove_boolean",
     "remove_representation",
     "unassign_representation",
+    "validate_type",
 ]

src/ifcopenshell-python/ifcopenshell/api/geometry/validate_type.py

@@ -0,0 +1,87 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import ifcopenshell.api.geometry
+import ifcopenshell.util.representation
+
+
+def validate_type(
+    file: ifcopenshell.file,
+    representation: ifcopenshell.entity_instance,
+    preferred_item: ifcopenshell.entity_instance | None = None,
+) -> bool:
+    """Validates the RepresentationType of an IfcShapeRepresentation
+
+    A shape representation has to identify its geometry using the
+    RepresentationType attribute. For example, if it holds tessellated
+    geometry, it should store "Tessellation" as its RepresentationType.
+
+    This function checks whether or not the RepresentationType is valid. This
+    is a wrapper around :func:`ifcopenshell.util.representation.guess_type`. It
+    will then set RepresentationType to the most appropriate value, or return
+    False otherwise. In addition, it also attempts to reconcile otherwise
+    invalid CSG geometry by unioning all remaining top level items to existing
+    boolean results.
+
+    :param representation: The IfcShapeRepresentation with Items
+    :param preferred_item: If the type is expected to be a CSG, this will be
+        the preferred item to union all remaining items to. If no preferred
+        item is provided, the first boolean result will be chosen.
+    :return: True if the representation type was set and it is a valid
+        combination, or False otherwise.
+    """
+    def is_operand(item):
+        return (
+            item.is_a("IfcBooleanResult")
+            or item.is_a("IfcCsgPrimitive3D")
+            or item.is_a("IfcHalfSpaceSolid")
+            or item.is_a("IfcSolidModel")
+            or item.is_a("IfcTessellatedFaceSet")
+        )
+
+    has_boolean = False
+    remaining_items = []
+    for item in representation.Items:
+        if item.is_a("IfcBooleanResult"):
+            has_boolean = True
+        if item != preferred_item and is_operand(item):
+            remaining_items.append(item)
+
+    if not has_boolean:
+        result = ifcopenshell.util.representation.guess_type(representation.Items)
+        if result:
+            representation.RepresentationType = result
+            return True
+        return False
+
+    if not preferred_item:
+        # Prioritise an existing boolean result
+        for i in remaining_items:
+            if i.is_a("IfcBooleanResult"):
+                preferred_item = i
+                break
+        if not preferred_item and remaining_items:
+            preferred_item = remaining_items[0]
+
+    if remaining_items:
+        ifcopenshell.api.geometry.add_boolean(file, preferred_item, remaining_items, "UNION")
+
+    representation.RepresentationType = ifcopenshell.util.representation.guess_type(representation.Items)
+    if representation.RepresentationType == "CSG":
+        return True
+    return False