|
|
@@ -211,9 +211,17 @@ def rewrite(state, lhs_m: UUID, rhs_m: UUID, pattern_mm: UUID, lhs_match: dict,
|
|
|
model_el_name_to_delete = lhs_match[pattern_name_to_delete]
|
|
|
# print('deleting', model_el_name_to_delete)
|
|
|
# Look up the matched element in the host graph
|
|
|
- el_to_delete, = bottom.read_outgoing_elements(host_m, model_el_name_to_delete)
|
|
|
- # Delete
|
|
|
- bottom.delete_element(el_to_delete)
|
|
|
+ els_to_delete = bottom.read_outgoing_elements(host_m, model_el_name_to_delete)
|
|
|
+ if len(els_to_delete) == 0:
|
|
|
+ # This can happen: if the SRC/TGT of a link was deleted, the link itself is also immediately deleted.
|
|
|
+ # If we then try to delete the link, it is not found (already gone).
|
|
|
+ # The most accurate way of handling this, would be to perform deletions in opposite order of creations (see the whole TryNextRound-mechanism above)
|
|
|
+ # However I *think* it is also OK to simply ignore this case.
|
|
|
+ pass
|
|
|
+ elif len(els_to_delete) == 1:
|
|
|
+ bottom.delete_element(els_to_delete[0])
|
|
|
+ else:
|
|
|
+ raise Exception("This should never happen!")
|
|
|
|
|
|
# 4. Object-level actions
|
|
|
# Iterate over the (now complete) mapping RHS -> Host
|
