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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
# Copyright (c) https://github.com/PyCQA/pylint/blob/main/CONTRIBUTORS.txt
"""Looks for try/except statements with too much code in the try clause."""
from __future__ import annotations
from typing import TYPE_CHECKING
from astroid import nodes
from pylint import checkers
from pylint.checkers import utils
from pylint.interfaces import HIGH
if TYPE_CHECKING:
from pylint.lint import PyLinter
class ConsiderRefactorIntoWhileConditionChecker(checkers.BaseChecker):
"""Checks for instances where while loops are implemented with a constant condition
which.
always evaluates to truthy and the first statement(s) is/are if statements which, when
evaluated.
to True, breaks out of the loop.
The if statement(s) can be refactored into the while loop.
"""
name = "consider_refactoring_into_while"
msgs = {
"R3501": (
"Consider using 'while %s' instead of 'while %s:' an 'if', and a 'break'",
"consider-refactoring-into-while-condition",
"Emitted when `while True:` loop is used and the first statement is a break condition. "
"The ``if / break`` construct can be removed if the check is inverted and moved to "
"the ``while`` statement.",
),
}
@utils.only_required_for_messages("consider-refactoring-into-while-condition")
def visit_while(self, node: nodes.While) -> None:
self._check_breaking_after_while_true(node)
def _check_breaking_after_while_true(self, node: nodes.While) -> None:
"""Check that any loop with an ``if`` clause has a break statement."""
if not isinstance(node.test, nodes.Const) or not node.test.bool_value():
return
pri_candidates: list[nodes.If] = []
for n in node.body:
if not isinstance(n, nodes.If):
break
pri_candidates.append(n)
candidates = []
tainted = False
for c in pri_candidates:
if tainted or not isinstance(c.body[0], nodes.Break):
break
candidates.append(c)
orelse = c.orelse
while orelse:
orelse_node = orelse[0]
if not isinstance(orelse_node, nodes.If):
tainted = True
else:
candidates.append(orelse_node)
if not isinstance(orelse_node, nodes.If):
break
orelse = orelse_node.orelse
candidates = [n for n in candidates if isinstance(n.body[0], nodes.Break)]
msg = " and ".join(
[f"({utils.not_condition_as_string(c.test)})" for c in candidates]
)
if len(candidates) == 1:
msg = utils.not_condition_as_string(candidates[0].test)
if not msg:
return
self.add_message(
"consider-refactoring-into-while-condition",
node=node,
line=node.lineno,
args=(msg, node.test.as_string()),
confidence=HIGH,
)
def register(linter: PyLinter) -> None:
linter.register_checker(ConsiderRefactorIntoWhileConditionChecker(linter))
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