Don't rely on util for basic ifcopenshell module capabilities. Keep util as an optional module for users to load.

src/ifcopenshell-python/ifcopenshell/__init__.py

@@ -36,8 +36,8 @@ from __future__ import print_function
 
 import os
 import sys
-import tempfile
 import zipfile
+import tempfile
 from pathlib import Path
 from typing import Optional
 
@@ -73,9 +73,11 @@ from . import guid
 from .file import file
 from .entity_instance import entity_instance, register_schema_attributes
 from .sql import sqlite, sqlite_entity
+
 try:
     from .stream import stream, stream_entity
-except: pass
+except:
+    pass
 
 READ_ERROR = ifcopenshell_wrapper.file_open_status.READ_ERROR
 NO_HEADER = ifcopenshell_wrapper.file_open_status.NO_HEADER
@@ -84,11 +86,13 @@ UNSUPPORTED_SCHEMA = ifcopenshell_wrapper.file_open_status.UNSUPPORTED_SCHEMA
 
 class Error(Exception):
     """Error used when a generic problem occurs"""
+
     pass
 
 
 class SchemaError(Error):
     """Error used when an IFC schema related problem occurs"""
+
     pass
 
 
@@ -114,7 +118,7 @@ def open(path: "os.PathLike | str", format: str = None, should_stream: bool = Fa
     """
     path = Path(path)
     if format is None:
-        format = ifcopenshell.util.file.guess_format(path)
+        format = guess_format(path)
     if format == ".ifcXML":
         f = ifcopenshell_wrapper.parse_ifcxml(str(path.absolute()))
         if f:
@@ -141,8 +145,7 @@ def open(path: "os.PathLike | str", format: str = None, should_stream: bool = Fa
             NO_HEADER: (Error, "Unable to parse IFC SPF header"),
             UNSUPPORTED_SCHEMA: (
                 SchemaError,
-                "Unsupported schema: %s"
-                % ",".join(f.header.file_schema.schema_identifiers),
+                "Unsupported schema: %s" % ",".join(f.header.file_schema.schema_identifiers),
             ),
         }[f.good().value()]
         raise exc(msg)
@@ -226,4 +229,31 @@ def schema_by_name(
     return ifcopenshell_wrapper.schema_by_name(schema)
 
 
+def guess_format(path: Path) -> Union[str | None]:
+    """Try to guess format using file extension
+
+    IFCs may be serialised as different formats. The most common is a ``.ifc``
+    file, which is plaintext and stores data using the STEP Physical File
+    format. IFC can also be stored as a Zipfile, XML, JSON, or SQL.
+
+    This will return the canonical form of the format. For example, if a path
+    has the extension of .xml or .ifcxml (case insensitive), it will return
+    .ifcXML.
+
+    :return: Either .ifc, .ifcZIP, .ifcXML, .ifcJSON, .ifcSQLite, or None.
+    """
+    suffix = path.suffix.lower()
+    if suffix == ".ifc":
+        return ".ifc"
+    elif suffix in (".ifczip", ".zip"):
+        return ".ifcZIP"
+    elif suffix in (".ifcxml", ".xml"):
+        return ".ifcXML"
+    elif suffix in (".ifcjson", ".json"):
+        return ".ifcJSON"
+    elif suffix in (".ifcsqlite", ".sqlite", ".db"):
+        return ".ifcSQLite"
+    return None
+
+
 from .main import *

src/ifcopenshell-python/ifcopenshell/file.py

@@ -27,11 +27,10 @@ import re
 import numbers
 import zipfile
 import functools
+import ifcopenshell
 from pathlib import Path
 from typing import Optional, Any
 
-import ifcopenshell.util.element
-import ifcopenshell.util.file
 from . import ifcopenshell_wrapper
 from .entity_instance import entity_instance
 
@@ -120,11 +119,19 @@ class Transaction:
         for inverse in self.file.get_inverse(element):
             inverse_references = []
             for i, attribute in enumerate(inverse):
-                if ifcopenshell.util.element.has_element_reference(attribute, element):
+                if self.has_element_reference(attribute, element):
                     inverse_references.append((i, self.serialise_value(inverse, attribute)))
             inverses[inverse.id()] = inverse_references
         return inverses
 
+    def has_element_reference(self, value: Any, element: ifcopenshell.entity_instance) -> bool:
+        if isinstance(value, (tuple, list)):
+            for v in value:
+                if self.has_element_reference(v, element):
+                    return True
+            return False
+        return value == element
+
     def rollback(self):
         for operation in self.operations[::-1]:
             if operation["action"] == "create":
@@ -376,14 +383,11 @@ class file(object):
             match = re.match(reg, self.wrapped_data.schema)
             version_tuple = tuple(
                 map(
-                    lambda pp: int(pp[1][len(pp[0]):]) if pp[1] else None,
+                    lambda pp: int(pp[1][len(pp[0]) :]) if pp[1] else None,
                     ((p, match.group(p)) for p in prefixes),
                 )
             )
-            return "".join(
-                "".join(map(str, t)) if t[1] else ""
-                for t in zip(prefixes, version_tuple[0:2])
-            )
+            return "".join("".join(map(str, t)) if t[1] else "" for t in zip(prefixes, version_tuple[0:2]))
         elif attr == "schema_identifier":
             return self.wrapped_data.schema
         elif attr == "schema_version":
@@ -576,7 +580,7 @@ class file(object):
         path = Path(path)
         path.parent.mkdir(parents=True, exist_ok=True)
         if format == None:
-            format = ifcopenshell.util.file.guess_format(path)
+            format = ifcopenshell.guess_format(path)
         if format == ".ifcXML":
             serializer = ifcopenshell_wrapper.XmlSerializer(self, str(path))
             serializer.finalize()

src/ifcopenshell-python/ifcopenshell/sql.py

@@ -2,7 +2,6 @@ try:
     import re
     import json
 
-    import ifcopenshell.util.schema
     from .file import file
     from . import ifcopenshell_wrapper
     from .entity_instance import entity_instance
@@ -56,6 +55,8 @@ class sqlite(file):
         self.preprocess_schema()
 
     def preprocess_schema(self):
+        import ifcopenshell.util.schema
+
         self.ifc_class_subtypes = {}
         self.ifc_class_attributes = {}
         self.ifc_class_inverse_attributes = {}
@@ -122,6 +123,9 @@ class sqlite(file):
             return entity
 
     def by_type(self, type, include_subtypes=True):
+        # TODO use cached subtypes
+        import ifcopenshell.util.schema
+
         if self.class_map:
             results = []
             subtypes = self.ifc_class_subtypes[type] if include_subtypes else self.ifc_class_subtypes[type][0:1]
@@ -167,7 +171,9 @@ class sqlite(file):
         return results
 
     def get_inverse(self, inst, allow_duplicate=False, with_attribute_indices=False):
-        query = f"SELECT inverses FROM {inst.sqlite_wrapper.ifc_class} WHERE `ifc_id` = {inst.sqlite_wrapper.id} LIMIT 1"
+        query = (
+            f"SELECT inverses FROM {inst.sqlite_wrapper.ifc_class} WHERE `ifc_id` = {inst.sqlite_wrapper.id} LIMIT 1"
+        )
         self.cursor.execute(query)
         row = self.cursor.fetchone()
         if not row or not row[0]:
@@ -198,9 +204,9 @@ class sqlite(file):
                     "verts": np.frombuffer(row["verts"]).tolist() if row["verts"] else [],
                     "edges": np.frombuffer(row["edges"], dtype=np.int64).tolist() if row["edges"] else [],
                     "faces": np.frombuffer(row["faces"], dtype=np.int64).tolist() if row["faces"] else [],
-                    "material_ids": np.frombuffer(row["material_ids"], dtype=np.int64).tolist()
-                    if row["material_ids"]
-                    else [],
+                    "material_ids": (
+                        np.frombuffer(row["material_ids"], dtype=np.int64).tolist() if row["material_ids"] else []
+                    ),
                     "materials": json.loads(row["materials"]) if row["materials"] else [],
                 }
             shapes[row["ifc_id"]] = {
@@ -353,7 +359,7 @@ class sqlite_entity(entity_instance):
     def get_info(self, include_identifier=True, recursive=False, return_type=dict, ignore=(), scalar_only=False):
         info = {"id": self.sqlite_wrapper.id, "type": self.sqlite_wrapper.ifc_class}
         if not self.sqlite_wrapper.attribute_cache:
-            self.__getitem__(0) # This will get all attributes
+            self.__getitem__(0)  # This will get all attributes
         info.update(self.sqlite_wrapper.attribute_cache)
         return info
 

src/ifcopenshell-python/ifcopenshell/util/file.py

@@ -1,29 +0,0 @@
-# IfcOpenShell - IFC toolkit and geometry engine
-# Copyright (C) 2021 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/>.
-
-from pathlib import Path
-
-
-def guess_format(path: Path) -> "str | None":
-    """Try to guess format using file extension"""
-    if path.suffix.lower() in (".ifczip", ".zip"):
-        return ".ifcZIP"
-    elif path.suffix.lower() in (".ifcxml", ".xml"):
-        return ".ifcXML"
-    elif path.suffix.lower() in (".ifcsqlite", ".sqlite", ".db"):
-        return ".ifcSQLite"