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

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

@@ -0,0 +1,48 @@
+import ifcopenshell
+import ifcopenshell.util.date
+from datetime import datetime
+
+
+class Data:
+    is_loaded = False
+    products = {}
+    objectives = {}
+
+    @classmethod
+    def purge(cls):
+        cls.is_loaded = False
+        cls.products = {}
+        cls.objectives = {}
+
+    @classmethod
+    def load(cls, file, product_id=None):
+        cls._file = file
+        if not cls._file:
+            return
+        if product_id:
+            return cls.load_product(product_id)
+        cls.load_objectives()
+        cls.is_loaded = True
+
+    @classmethod
+    def load_product(cls, product_id):
+        product = cls._file.by_id(product_id)
+        cls.products[product_id] = []
+        if not product.HasAssociations:
+            return
+        for association in product.HasAssociations:
+            if association.is_a("IfcRelAssociatesConstraint"):
+                if not association.RelatingConstraint.is_a("IfcObjective"):
+                    continue  # not yet implemented
+                cls.products[product_id].append(association.RelatingConstraint.id())
+
+    @classmethod
+    def load_objectives(cls):
+        cls.objectives = {}
+        for constraint in cls._file.by_type("IfcObjective"):
+            data = constraint.get_info()
+            if cls._file.schema == "IFC2X3":
+                for attribute in ["CreationTime"]:
+                    if data[attribute]:
+                        data[attribute] = ifcopenshell.util.date.ifc2datetime(data[attribute]).isoformat()
+            cls.objectives[constraint.id()] = data