Use constant time parent enumeration lookup

src/ifcexpressparser/implementation.py

@@ -167,12 +167,15 @@ class Implementation(codegen.Base):
             'name'           : name,
             'padding'        : ' ' * (max_len - len(name))
         } for name in enumerable_types]
+        
+        enumeration_index_by_str = dict((j,i) for i,j in enumerate(enumerable_types))
+        def get_parent_id(s):
+            e = mapping.schema.entities.get(s)
+            if e and e.supertypes: 
+                return enumeration_index_by_str[e.supertypes[0]]
+            else: return -1
 
-        parent_type_statements = [templates.parent_type_stmt % {
-            'name'    : name,
-            'parent'  : type.supertypes[0],
-            'padding' : ' ' * (max_len - len(name))
-        } for name, type in mapping.schema.entities.items() if type.supertypes and len(type.supertypes) == 1]
+        parent_type_statements = ",".join(map(str, map(get_parent_id, enumerable_types)))
 
         max_id = len(enumerable_types)
 
@@ -225,7 +228,7 @@ class Implementation(codegen.Base):
             'type_name_strings'        : type_name_strings,
             'string_map_statements'    : catnl(string_map_statements),
             'simple_type_statement'    : simple_type_statements,
-            'parent_type_statements'   : catnl(parent_type_statements),
+            'parent_type_statements'   : parent_type_statements,
             'entity_implementations'   : catnl(entity_implementations),
             'simple_type_impl'         : catnl(simple_type_impl)
         }