[ports2data] deal with cycles better

masque/utils/ports2data.py

@@ -57,11 +57,9 @@ def data_to_ports(
         name: str | None = None,     # Note: name optional, but arg order different from read(postprocess=)
         max_depth: int = 0,
         skip_subcells: bool = True,
-        # TODO missing ok?
+        visited: set[int] | None = None,
         ) -> Pattern:
     """
-    # TODO fixup documentation in ports2data
-    # TODO move to utils.file?
     Examine `pattern` for labels specifying port info, and use that info
       to fill out its `ports` attribute.
 
@@ -70,18 +68,28 @@ def data_to_ports(
 
     Args:
         layers: Search for labels on all the given layers.
+        library: Mapping from pattern names to patterns.
         pattern: Pattern object to scan for labels.
-        max_depth: Maximum hierarcy depth to search. Default 999_999.
+        name: Name of the pattern object.
+        max_depth: Maximum hierarcy depth to search. Default 0.
             Reduce this to 0 to avoid ever searching subcells.
         skip_subcells: If port labels are found at a given hierarcy level,
             do not continue searching at deeper levels. This allows subcells
             to contain their own port info without interfering with supercells'
             port data.
             Default True.
+        visited: Set of object IDs which have already been processed.
 
     Returns:
         The updated `pattern`. Port labels are not removed.
     """
+    if visited is None:
+        visited = set()
+
+    if id(pattern) in visited:
+        return pattern
+    visited.add(id(pattern))
+
     if pattern.ports:
         logger.warning(f'Pattern {name if name else pattern} already had ports, skipping data_to_ports')
         return pattern
@@ -105,6 +113,7 @@ def data_to_ports(
             name = target,
             max_depth = max_depth - 1,
             skip_subcells = skip_subcells,
+            visited = visited,
             )
         found_ports |= bool(pp.ports)