# 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
from __future__ import annotations
from typing import TYPE_CHECKING
from astroid import nodes
from pylint.checkers import BaseChecker
from pylint.checkers.utils import only_required_for_messages
if TYPE_CHECKING:
from pylint.lint import PyLinter
class SetMembershipChecker(BaseChecker):
name = "set_membership"
msgs = {
"R6201": (
"Consider using set for membership test",
"use-set-for-membership",
"Membership tests are more efficient when performed on "
"a lookup optimized datatype like ``sets``.",
),
}
def __init__(self, linter: PyLinter) -> None:
"""Initialize checker instance."""
super().__init__(linter=linter)
@only_required_for_messages("use-set-for-membership")
def visit_compare(self, node: nodes.Compare) -> None:
for op, comparator in node.ops:
if op == "in":
self._check_in_comparison(comparator)
def _check_in_comparison(self, comparator: nodes.NodeNG) -> None:
"""Checks for membership comparisons with in-place container objects."""
if not isinstance(comparator, nodes.BaseContainer) or isinstance(
comparator, nodes.Set
):
return
# Heuristic - We need to be sure all items in set are hashable
if all(isinstance(item, nodes.Const) for item in comparator.elts):
self.add_message("use-set-for-membership", node=comparator)
def register(linter: PyLinter) -> None:
linter.register_checker(SetMembershipChecker(linter))
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