First attempt at ripping out agnostic code into ifcopenshell.api namespace. See #1399.

src/ifcopenshell-python/ifcopenshell/api/spatial/data.py

@@ -0,0 +1,50 @@
+class Data:
+    products = {}
+    spatial_elements = {}
+
+    @classmethod
+    def purge(cls):
+        cls.products = {}
+        cls.spatial_elements = {}
+
+    @classmethod
+    def load(cls, file, product_id=None):
+        if product_id:
+            return cls.load_product(file, product_id)
+        cls.load_spatial_elements(file)
+
+    @classmethod
+    def load_product(cls, file, product_id):
+        if not file:
+            return
+        product = file.by_id(product_id)
+        if not hasattr(product, "ContainedInStructure"):
+            cls.products[product_id] = None
+        elif product.ContainedInStructure:
+            structure = product.ContainedInStructure[0].RelatingStructure
+            cls.products[product_id] = {"type": structure.is_a(), "Name": structure.Name, "id": int(structure.id())}
+        else:
+            cls.products[product_id] = {"type": None, "Name": None, "id": None}
+
+    @classmethod
+    def load_spatial_elements(cls, file):
+        if not file:
+            return
+        cls.spatial_elements = {}
+        ifc_class = "IfcSpatialElement"
+        if file.schema == "IFC2X3":
+            ifc_class = "IfcSpatialStructureElement"
+        for element in file.by_type(ifc_class):
+            decomposes = None
+            if element.Decomposes:
+                decomposes = element.Decomposes[0].RelatingObject.id()
+            is_decomposed_by = []
+            if element.IsDecomposedBy:
+                for rel in element.IsDecomposedBy:
+                    is_decomposed_by.extend([e.id() for e in rel.RelatedObjects])
+            cls.spatial_elements[element.id()] = {
+                "Name": element.Name,
+                "LongName": element.LongName,
+                "Decomposes": decomposes,
+                "IsDecomposedBy": is_decomposed_by
+            }