Add Optimise recipe to ifcpatch

src/ifcpatch/recipes/Optimise.py

@@ -0,0 +1,66 @@
+import ifcopenshell
+import ifcopenshell.util.element
+from toposort import toposort_flatten as toposort
+
+
+
+class Patcher:
+    def __init__(self, src, file, logger, args=None):
+        self.src = src
+        self.file = file
+        self.logger = logger
+        self.args = args
+        self.optimized_file = ifcopenshell.file(schema=self.file.schema)
+
+
+    def patch(self):
+        def generate_instances_and_references():
+            """
+            Generator which yields an entity id and 
+            the set of all of its references contained in its attributes. 
+            """
+            for inst in self.file:
+                yield inst.id(), set(i.id() for i in self.file.traverse(inst)[1:] if i.id())
+
+        instance_mapping = {}
+
+
+        def map_value(v):
+            """
+            Recursive function which replicates an entity instance, with 
+            its attributes, mapping references to already registered
+            instances. Indeed, because of the toposort we know that 
+            forward attribute value instances are mapped before the instances
+            that reference them.
+            """
+            if isinstance(v, (list, tuple)):
+                # lists are recursively traversed
+                return type(v)(map(map_value, v))
+            elif isinstance(v, ifcopenshell.entity_instance):
+                if v.id() == 0:
+                    # express simple types are not part of the toposort and just copied
+                    return self.optimized_file.create_entity(v.is_a(), v[0])
+          
+                
+                return instance_mapping[v]
+            else:
+                # a plain python value can just be returned
+                return v
+
+        info_to_id = {}
+            
+        for id in toposort(dict(generate_instances_and_references())):
+            inst = self.file[id]
+            info = inst.get_info(include_identifier=False, recursive=True, return_type=frozenset)
+            if info in info_to_id:
+                mapped = instance_mapping[inst] = instance_mapping[self.file[info_to_id[info]]]
+
+            else:
+                info_to_id[info] = id
+                instance_mapping[inst] = self.optimized_file.create_entity(
+                    inst.is_a(),
+                    *map(map_value, inst)
+                )
+
+        self.file = self.optimized_file
+