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"""Check for use of for loops that only check for a condition."""
from typing import TYPE_CHECKING
from astroid import nodes
from pylint.checkers import BaseChecker
from pylint.checkers.utils import check_messages, returns_bool
from pylint.interfaces import IAstroidChecker
if TYPE_CHECKING:
from pylint.lint.pylinter import PyLinter
class ConsiderUsingAnyOrAllChecker(BaseChecker):
__implements__ = (IAstroidChecker,)
name = "consider-using-any-or-all"
msgs = {
"C0501": (
"`for` loop could be `%s`",
"consider-using-any-or-all",
"A for loop that checks for a condition and return a bool can be replaced with any or all.",
)
}
@check_messages("consider-using-any-or-all")
def visit_for(self, node: nodes.For) -> None:
if len(node.body) != 1: # Only If node with no Else
return
if not isinstance(node.body[0], nodes.If):
return
if_children = list(node.body[0].get_children())
if not len(if_children) == 2: # The If node has only a comparison and return
return
if not returns_bool(if_children[1]):
return
# Check for terminating boolean return right after the loop
node_after_loop = node.next_sibling()
if returns_bool(node_after_loop):
final_return_bool = node_after_loop.value.value
suggested_string = self._build_suggested_string(node, final_return_bool)
self.add_message(
"consider-using-any-or-all", node=node, args=suggested_string
)
@staticmethod
def _build_suggested_string(node: nodes.For, final_return_bool: bool) -> str:
"""When a nodes.For node can be rewritten as an any/all statement, return a suggestion for that statement
final_return_bool is the boolean literal returned after the for loop if all conditions fail
"""
loop_var = node.target.as_string()
loop_iter = node.iter.as_string()
test_node = next(node.body[0].get_children())
if isinstance(test_node, nodes.UnaryOp) and test_node.op == "not":
# The condition is negated. Advance the node to the operand and modify the suggestion
test_node = test_node.operand
suggested_function = "all" if final_return_bool else "not all"
else:
suggested_function = "not any" if final_return_bool else "any"
test = test_node.as_string()
return f"{suggested_function}({test} for {loop_var} in {loop_iter})"
def register(linter: "PyLinter") -> None:
"""Required method to auto register this checker.
:param linter: Main interface object for Pylint plugins
"""
linter.register_checker(ConsiderUsingAnyOrAllChecker(linter))
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