# 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
# Copyright (c) https://github.com/PyCQA/pylint/blob/main/CONTRIBUTORS.txt
import astroid
from astroid import nodes
from pylint import checkers
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
"""
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.only_required_for_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(future=True)
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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