PDDL Parser: more explicit error when facing empty expressions

aibasel · Jul 20, 2021 · cffea5c · cffea5c
1 parent bdfedac
commit cffea5c
Show file tree

Hide file tree

Showing 2 changed files with 5 additions and 0 deletions.
diff --git a/CHANGES.md b/CHANGES.md
@@ -11,6 +11,9 @@ after the corresponding tracker issues.
 
 ## Changes since the last release
 
+- Better error messages for empty preconditions.
+  <http://issues.fast-downward.org/issue1030>
+
 - Add debugging methods to LP solver interface.
   <http://issues.fast-downward.org/issue960>
   You can now assign names to LP variables and constraints for easier

diff --git a/src/translate/pddl_parser/parsing_functions.py b/src/translate/pddl_parser/parsing_functions.py
@@ -61,6 +61,8 @@ def parse_condition(alist, type_dict, predicate_dict):
 
 def parse_condition_aux(alist, negated, type_dict, predicate_dict):
     """Parse a PDDL condition. The condition is translated into NNF on the fly."""
+    if not alist:
+        raise RuntimeError("Empty condition expression")
     tag = alist[0]
     if tag in ("and", "or", "not", "imply"):
         args = alist[1:]