Solved bug that occurred when parsing problems whose goal contained a…

… single atom

setup.py

@@ -4,7 +4,7 @@
     long_description = fh.read()
 
 setuptools.setup(name='lifted-pddl',
-      version='1.2.1',
+      version='1.2.2',
       description='A lightweight framework for parsing PDDL in lifted form.',
       long_description=long_description,
       long_description_content_type="text/markdown",

src/lifted_pddl/__init__.py

@@ -1,5 +1,5 @@
 # __init__.py
 
-__version__ = "1.2.1"
+__version__ = "1.2.2"
 
 from lifted_pddl.parser import Parser

src/lifted_pddl/parser.py

@@ -246,9 +246,15 @@ def parse_problem(self, problem_path):
 		# Each goal is represented as a tuple (is_true, pred_name, object_indexes)
 		# object_indexes is a tuple containing the index of each object the atom of the goal is instantiated on
 		# is_true equals False if the goal is negative (e.g., (not (at t1 l1)) ) and True otherwise
-		subformulas = problem.goal.subformulas
-		self.goals = set([(True, x.predicate.name, tuple(self.object_names.index(obj.name) for obj in x.subterms)) if isinstance(x, Atom) else \
-					  (False, x.subformulas[0].predicate.name, tuple(self.object_names.index(obj.name) for obj in x.subformulas[0].subterms)) for x in subformulas])
+
+		# The goal contains a single atom (e.g., ( :goal (and (on b2 b1))) )
+		if isinstance(problem.goal, Atom):
+			self.goals = set([(True, problem.goal.predicate.name, tuple(self.object_names.index(obj.name) for obj in problem.goal.subterms))])			
+
+		else: # The goal contains more than a single atom
+			subformulas = problem.goal.subformulas
+			self.goals = set([(True, x.predicate.name, tuple(self.object_names.index(obj.name) for obj in x.subterms)) if isinstance(x, Atom) else \
+						  (False, x.subformulas[0].predicate.name, tuple(self.object_names.index(obj.name) for obj in x.subformulas[0].subterms)) for x in subformulas])
 
 	# Returns the name of the object whose index is @obj_ind
 	def get_object_name(self, obj_ind):