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- # Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
- # For details: https://github.com/PyCQA/pylint/blob/main/LICENSE
- import astroid
- from astroid import nodes
- from pylint import checkers, interfaces
- from pylint.checkers import utils
- class NotChecker(checkers.BaseChecker):
- """checks for too many not in comparison expressions
- - "not not" should trigger a warning
- - "not" followed by a comparison should trigger a warning
- """
- __implements__ = (interfaces.IAstroidChecker,)
- msgs = {
- "C0113": (
- 'Consider changing "%s" to "%s"',
- "unneeded-not",
- "Used when a boolean expression contains an unneeded negation.",
- )
- }
- name = "refactoring"
- reverse_op = {
- "<": ">=",
- "<=": ">",
- ">": "<=",
- ">=": "<",
- "==": "!=",
- "!=": "==",
- "in": "not in",
- "is": "is not",
- }
- # sets are not ordered, so for example "not set(LEFT_VALS) <= set(RIGHT_VALS)" is
- # not equivalent to "set(LEFT_VALS) > set(RIGHT_VALS)"
- skipped_nodes = (nodes.Set,)
- # 'builtins' py3, '__builtin__' py2
- skipped_classnames = [f"builtins.{qname}" for qname in ("set", "frozenset")]
- @utils.check_messages("unneeded-not")
- def visit_unaryop(self, node: nodes.UnaryOp) -> None:
- if node.op != "not":
- return
- operand = node.operand
- if isinstance(operand, nodes.UnaryOp) and operand.op == "not":
- self.add_message(
- "unneeded-not",
- node=node,
- args=(node.as_string(), operand.operand.as_string()),
- )
- elif isinstance(operand, nodes.Compare):
- left = operand.left
- # ignore multiple comparisons
- if len(operand.ops) > 1:
- return
- operator, right = operand.ops[0]
- if operator not in self.reverse_op:
- return
- # Ignore __ne__ as function of __eq__
- frame = node.frame()
- if frame.name == "__ne__" and operator == "==":
- return
- for _type in (utils.node_type(left), utils.node_type(right)):
- if not _type:
- return
- if isinstance(_type, self.skipped_nodes):
- return
- if (
- isinstance(_type, astroid.Instance)
- and _type.qname() in self.skipped_classnames
- ):
- return
- suggestion = (
- f"{left.as_string()} {self.reverse_op[operator]} {right.as_string()}"
- )
- self.add_message(
- "unneeded-not", node=node, args=(node.as_string(), suggestion)
- )
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