diff options
| -rw-r--r-- | Lib/test/test_peg_generator/test_pegen.py | 8 | ||||
| -rw-r--r-- | Tools/peg_generator/pegen/python_generator.py | 8 |
2 files changed, 15 insertions, 1 deletions
diff --git a/Lib/test/test_peg_generator/test_pegen.py b/Lib/test/test_peg_generator/test_pegen.py index 30e1b67564..5b4e964d69 100644 --- a/Lib/test/test_peg_generator/test_pegen.py +++ b/Lib/test/test_peg_generator/test_pegen.py @@ -493,6 +493,14 @@ class TestPegen(unittest.TestCase): # Would assert False without a special case in compute_left_recursives(). make_parser(grammar) + def test_opt_sequence(self) -> None: + grammar = """ + start: [NAME*] + """ + # This case was failing because of a double trailing comma at the end + # of a line in the generated source. See bpo-41044 + make_parser(grammar) + def test_left_recursion_too_complex(self) -> None: grammar = """ start: foo diff --git a/Tools/peg_generator/pegen/python_generator.py b/Tools/peg_generator/pegen/python_generator.py index 64336552f2..45a75975db 100644 --- a/Tools/peg_generator/pegen/python_generator.py +++ b/Tools/peg_generator/pegen/python_generator.py @@ -93,7 +93,13 @@ class PythonCallMakerVisitor(GrammarVisitor): def visit_Opt(self, node: Opt) -> Tuple[str, str]: name, call = self.visit(node.node) - return "opt", f"{call}," # Note trailing comma! + # Note trailing comma (the call may already have one comma + # at the end, for example when rules have both repeat0 and optional + # markers, e.g: [rule*]) + if call.endswith(","): + return "opt", call + else: + return "opt", f"{call}," def visit_Repeat0(self, node: Repeat0) -> Tuple[str, str]: if node in self.cache: |