Class diagram can be rendered as object diagram textual syntax, and parsed back, without information loss

concrete_syntax/textual_od/renderer.py

@@ -0,0 +1,43 @@
+# Renderer for Object Diagrams textual concrete syntax
+
+from services import od
+from services.bottom.V0 import Bottom
+import json
+
+def display_value(val: any):
+    if isinstance(val, str):
+        return '"'+val+'"'
+    elif isinstance(val, int) or isinstance(val, bool):
+        return str(val)
+    else:
+        raise Exception("don't know how to display value" + str(val))
+
+def render_od(state, m_id, mm_id, hide_names=True):
+    bottom = Bottom(state)
+    output = ""
+    
+    m_od = od.OD(mm_id, m_id, state)
+
+    def display_name(name: str):
+        # object names that start with "__" are hidden
+        return name if (name[0:2] != "__" or not hide_names) else ""
+
+    def write_attributes(object_node):
+        o = ""
+        for attr_name, slot_node in m_od.get_slots(object_node):
+            value = m_od.read_slot(slot_node)
+            o += f"    {attr_name} = {display_value(value)}\n"
+        return o
+
+    for class_name, objects in m_od.get_all_objects().items():
+        for object_name, object_node in objects.items():
+            output += f"{display_name(object_name)}:{class_name}\n"
+            output += write_attributes(object_node)
+
+    for assoc_name, links in m_od.get_all_links().items():
+        for link_name, (link_edge, src_name, tgt_name) in links.items():
+            output += f"{display_name(link_name)}:{assoc_name} ({src_name} -> {tgt_name})\n"
+            # links can also have slots:
+            output += write_attributes(link_edge)
+
+    return output