201 lines
7.5 KiB
Python
201 lines
7.5 KiB
Python
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# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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# For details: https://github.com/pylint-dev/pylint/blob/main/LICENSE
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# Copyright (c) https://github.com/pylint-dev/pylint/blob/main/CONTRIBUTORS.txt
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from __future__ import annotations
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from typing import TYPE_CHECKING
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from astroid import nodes
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from pylint import checkers, interfaces
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from pylint.checkers import utils
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if TYPE_CHECKING:
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from pylint.lint import PyLinter
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_LIST_MODIFIER_METHODS = {"append", "remove"}
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_SET_MODIFIER_METHODS = {"add", "remove"}
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class ModifiedIterationChecker(checkers.BaseChecker):
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"""Checks for modified iterators in for loops iterations.
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Currently supports `for` loops for Sets, Dictionaries and Lists.
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"""
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name = "modified_iteration"
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msgs = {
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"W4701": (
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"Iterated list '%s' is being modified inside for loop body, consider iterating through a copy of it "
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"instead.",
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"modified-iterating-list",
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"Emitted when items are added or removed to a list being iterated through. "
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"Doing so can result in unexpected behaviour, that is why it is preferred to use a copy of the list.",
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),
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"E4702": (
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"Iterated dict '%s' is being modified inside for loop body, iterate through a copy of it instead.",
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"modified-iterating-dict",
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"Emitted when items are added or removed to a dict being iterated through. "
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"Doing so raises a RuntimeError.",
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),
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"E4703": (
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"Iterated set '%s' is being modified inside for loop body, iterate through a copy of it instead.",
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"modified-iterating-set",
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"Emitted when items are added or removed to a set being iterated through. "
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"Doing so raises a RuntimeError.",
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),
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}
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options = ()
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@utils.only_required_for_messages(
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"modified-iterating-list", "modified-iterating-dict", "modified-iterating-set"
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)
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def visit_for(self, node: nodes.For) -> None:
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iter_obj = node.iter
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for body_node in node.body:
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self._modified_iterating_check_on_node_and_children(body_node, iter_obj)
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def _modified_iterating_check_on_node_and_children(
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self, body_node: nodes.NodeNG, iter_obj: nodes.NodeNG
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) -> None:
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"""See if node or any of its children raises modified iterating messages."""
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self._modified_iterating_check(body_node, iter_obj)
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for child in body_node.get_children():
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self._modified_iterating_check_on_node_and_children(child, iter_obj)
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def _modified_iterating_check(
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self, node: nodes.NodeNG, iter_obj: nodes.NodeNG
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) -> None:
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msg_id = None
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if isinstance(node, nodes.Delete) and any(
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self._deleted_iteration_target_cond(t, iter_obj) for t in node.targets
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):
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inferred = utils.safe_infer(iter_obj)
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if isinstance(inferred, nodes.List):
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msg_id = "modified-iterating-list"
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elif isinstance(inferred, nodes.Dict):
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msg_id = "modified-iterating-dict"
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elif isinstance(inferred, nodes.Set):
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msg_id = "modified-iterating-set"
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elif not isinstance(iter_obj, (nodes.Name, nodes.Attribute)):
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pass
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elif self._modified_iterating_list_cond(node, iter_obj):
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msg_id = "modified-iterating-list"
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elif self._modified_iterating_dict_cond(node, iter_obj):
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msg_id = "modified-iterating-dict"
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elif self._modified_iterating_set_cond(node, iter_obj):
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msg_id = "modified-iterating-set"
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if msg_id:
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self.add_message(
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msg_id,
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node=node,
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args=(iter_obj.repr_name(),),
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confidence=interfaces.INFERENCE,
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)
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@staticmethod
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def _is_node_expr_that_calls_attribute_name(node: nodes.NodeNG) -> bool:
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return (
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isinstance(node, nodes.Expr)
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and isinstance(node.value, nodes.Call)
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and isinstance(node.value.func, nodes.Attribute)
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and isinstance(node.value.func.expr, nodes.Name)
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)
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@staticmethod
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def _common_cond_list_set(
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node: nodes.Expr,
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iter_obj: nodes.Name | nodes.Attribute,
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infer_val: nodes.List | nodes.Set,
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) -> bool:
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iter_obj_name = (
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iter_obj.attrname
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if isinstance(iter_obj, nodes.Attribute)
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else iter_obj.name
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)
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return (infer_val == utils.safe_infer(iter_obj)) and ( # type: ignore[no-any-return]
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node.value.func.expr.name == iter_obj_name
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)
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@staticmethod
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def _is_node_assigns_subscript_name(node: nodes.NodeNG) -> bool:
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return isinstance(node, nodes.Assign) and (
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isinstance(node.targets[0], nodes.Subscript)
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and (isinstance(node.targets[0].value, nodes.Name))
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)
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def _modified_iterating_list_cond(
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self, node: nodes.NodeNG, iter_obj: nodes.Name | nodes.Attribute
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) -> bool:
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if not self._is_node_expr_that_calls_attribute_name(node):
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return False
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infer_val = utils.safe_infer(node.value.func.expr)
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if not isinstance(infer_val, nodes.List):
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return False
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return (
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self._common_cond_list_set(node, iter_obj, infer_val)
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and node.value.func.attrname in _LIST_MODIFIER_METHODS
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)
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def _modified_iterating_dict_cond(
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self, node: nodes.NodeNG, iter_obj: nodes.Name | nodes.Attribute
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) -> bool:
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if not self._is_node_assigns_subscript_name(node):
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return False
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# Do not emit when merely updating the same key being iterated
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if (
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isinstance(iter_obj, nodes.Name)
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and iter_obj.name == node.targets[0].value.name
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and isinstance(iter_obj.parent.target, nodes.AssignName)
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and isinstance(node.targets[0].slice, nodes.Name)
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and iter_obj.parent.target.name == node.targets[0].slice.name
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):
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return False
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infer_val = utils.safe_infer(node.targets[0].value)
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if not isinstance(infer_val, nodes.Dict):
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return False
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if infer_val != utils.safe_infer(iter_obj):
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return False
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if isinstance(iter_obj, nodes.Attribute):
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iter_obj_name = iter_obj.attrname
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else:
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iter_obj_name = iter_obj.name
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return node.targets[0].value.name == iter_obj_name # type: ignore[no-any-return]
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def _modified_iterating_set_cond(
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self, node: nodes.NodeNG, iter_obj: nodes.Name | nodes.Attribute
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) -> bool:
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if not self._is_node_expr_that_calls_attribute_name(node):
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return False
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infer_val = utils.safe_infer(node.value.func.expr)
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if not isinstance(infer_val, nodes.Set):
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return False
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return (
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self._common_cond_list_set(node, iter_obj, infer_val)
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and node.value.func.attrname in _SET_MODIFIER_METHODS
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)
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def _deleted_iteration_target_cond(
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self, node: nodes.DelName, iter_obj: nodes.NodeNG
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) -> bool:
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if not isinstance(node, nodes.DelName):
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return False
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if not isinstance(iter_obj.parent, nodes.For):
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return False
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if not isinstance(
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iter_obj.parent.target, (nodes.AssignName, nodes.BaseContainer)
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):
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return False
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return any(
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t == node.name
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for t in utils.find_assigned_names_recursive(iter_obj.parent.target)
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)
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def register(linter: PyLinter) -> None:
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linter.register_checker(ModifiedIterationChecker(linter))
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