diff options
Diffstat (limited to 'pylint/checkers/refactoring/implicit_booleaness_checker.py')
| -rw-r--r-- | pylint/checkers/refactoring/implicit_booleaness_checker.py | 58 |
1 files changed, 56 insertions, 2 deletions
diff --git a/pylint/checkers/refactoring/implicit_booleaness_checker.py b/pylint/checkers/refactoring/implicit_booleaness_checker.py index ff1a36205..93ac44269 100644 --- a/pylint/checkers/refactoring/implicit_booleaness_checker.py +++ b/pylint/checkers/refactoring/implicit_booleaness_checker.py @@ -81,6 +81,15 @@ class ImplicitBooleanessChecker(checkers.BaseChecker): "of a collection classes; empty collections are considered as false", ), "C1804": ( + '"%s" can be simplified to "%s" as an empty string is falsey', + "use-implicit-booleaness-not-comparison-to-string", + "Used when Pylint detects comparison to an empty string constant.", + { + "default_enabled": False, + "old_names": [("C1901", "compare-to-empty-string")], + }, + ), + "C1805": ( '"%s" can be simplified to "%s" as 0 is falsey', "use-implicit-booleaness-not-comparison-to-zero", "Used when Pylint detects comparison to a 0 constant.", @@ -162,12 +171,16 @@ class ImplicitBooleanessChecker(checkers.BaseChecker): "use-implicit-booleaness-not-len", node=node, confidence=HIGH ) - @utils.only_required_for_messages("use-implicit-booleaness-not-comparison") + @utils.only_required_for_messages( + "use-implicit-booleaness-not-comparison", + "use-implicit-booleaness-not-comparison-to-string", + "use-implicit-booleaness-not-comparison-to-zero", + ) def visit_compare(self, node: nodes.Compare) -> None: self._check_use_implicit_booleaness_not_comparison(node) self._check_compare_to_zero(node) + self._check_compare_to_string(node) - @utils.only_required_for_messages("compare-to-zero") def _check_compare_to_zero(self, node: nodes.Compare) -> None: # pylint: disable=duplicate-code _operators = ["!=", "==", "is not", "is"] @@ -209,6 +222,47 @@ class ImplicitBooleanessChecker(checkers.BaseChecker): confidence=HIGH, ) + def _check_compare_to_string(self, node: nodes.Compare) -> None: + """Checks for comparisons to empty string. + + Most of the time you should use the fact that empty strings are false. + An exception to this rule is when an empty string value is allowed in the program + and has a different meaning than None! + """ + _operators = {"!=", "==", "is not", "is"} + # note: astroid.Compare has the left most operand in node.left while the rest + # are a list of tuples in node.ops the format of the tuple is + # ('compare operator sign', node) here we squash everything into `ops` + # to make it easier for processing later + ops: list[tuple[str, nodes.NodeNG | None]] = [("", node.left)] + ops.extend(node.ops) + iter_ops = iter(ops) + ops = list(itertools.chain(*iter_ops)) # type: ignore[arg-type] + for ops_idx in range(len(ops) - 2): + op_1: nodes.NodeNG | None = ops[ops_idx] + op_2: str = ops[ops_idx + 1] # type: ignore[assignment] + op_3: nodes.NodeNG | None = ops[ops_idx + 2] + error_detected = False + if op_1 is None or op_3 is None or op_2 not in _operators: + continue + node_name = "" + # x ?? "" + if utils.is_empty_str_literal(op_1): + error_detected = True + node_name = op_3.as_string() + # '' ?? X + elif utils.is_empty_str_literal(op_3): + error_detected = True + node_name = op_1.as_string() + if error_detected: + suggestion = f"not {node_name}" if op_2 in {"==", "is"} else node_name + self.add_message( + "compare-to-empty-string", + args=(node.as_string(), suggestion), + node=node, + confidence=HIGH, + ) + def _check_use_implicit_booleaness_not_comparison( self, node: nodes.Compare ) -> None: |