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# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
# For details: https://github.com/pylint-dev/astroid/blob/main/LICENSE
# Copyright (c) https://github.com/pylint-dev/astroid/blob/main/CONTRIBUTORS.txt
"""_filter_stmts and helper functions.
This method gets used in LocalsDictnodes.NodeNG._scope_lookup.
It is not considered public.
"""
from __future__ import annotations
from astroid import nodes
from astroid.nodes import node_classes
from astroid.typing import SuccessfulInferenceResult
def _get_filtered_node_statements(
base_node: nodes.NodeNG, stmt_nodes: list[nodes.NodeNG]
) -> list[tuple[nodes.NodeNG, nodes.Statement]]:
statements = [(node, node.statement(future=True)) for node in stmt_nodes]
# Next we check if we have ExceptHandlers that are parent
# of the underlying variable, in which case the last one survives
if len(statements) > 1 and all(
isinstance(stmt, nodes.ExceptHandler) for _, stmt in statements
):
statements = [
(node, stmt) for node, stmt in statements if stmt.parent_of(base_node)
]
return statements
def _is_from_decorator(node) -> bool:
"""Return whether the given node is the child of a decorator."""
return any(isinstance(parent, nodes.Decorators) for parent in node.node_ancestors())
def _get_if_statement_ancestor(node: nodes.NodeNG) -> nodes.If | None:
"""Return the first parent node that is an If node (or None)."""
for parent in node.node_ancestors():
if isinstance(parent, nodes.If):
return parent
return None
def _filter_stmts(
base_node: node_classes.LookupMixIn,
stmts: list[SuccessfulInferenceResult],
frame: nodes.LocalsDictNodeNG,
offset: int,
) -> list[nodes.NodeNG]:
"""Filter the given list of statements to remove ignorable statements.
If base_node is not a frame itself and the name is found in the inner
frame locals, statements will be filtered to remove ignorable
statements according to base_node's location.
:param stmts: The statements to filter.
:param frame: The frame that all of the given statements belong to.
:param offset: The line offset to filter statements up to.
:returns: The filtered statements.
"""
# if offset == -1, my actual frame is not the inner frame but its parent
#
# class A(B): pass
#
# we need this to resolve B correctly
if offset == -1:
myframe = base_node.frame().parent.frame()
else:
myframe = base_node.frame()
# If the frame of this node is the same as the statement
# of this node, then the node is part of a class or
# a function definition and the frame of this node should be the
# the upper frame, not the frame of the definition.
# For more information why this is important,
# see Pylint issue #295.
# For example, for 'b', the statement is the same
# as the frame / scope:
#
# def test(b=1):
# ...
if (
base_node.parent
and base_node.statement(future=True) is myframe
and myframe.parent
):
myframe = myframe.parent.frame()
mystmt: nodes.Statement | None = None
if base_node.parent:
mystmt = base_node.statement(future=True)
# line filtering if we are in the same frame
#
# take care node may be missing lineno information (this is the case for
# nodes inserted for living objects)
if myframe is frame and mystmt and mystmt.fromlineno is not None:
assert mystmt.fromlineno is not None, mystmt
mylineno = mystmt.fromlineno + offset
else:
# disabling lineno filtering
mylineno = 0
_stmts: list[nodes.NodeNG] = []
_stmt_parents = []
statements = _get_filtered_node_statements(base_node, stmts)
for node, stmt in statements:
# line filtering is on and we have reached our location, break
if stmt.fromlineno and stmt.fromlineno > mylineno > 0:
break
# Ignore decorators with the same name as the
# decorated function
# Fixes issue #375
if mystmt is stmt and _is_from_decorator(base_node):
continue
if node.has_base(base_node):
break
if isinstance(node, nodes.EmptyNode):
# EmptyNode does not have assign_type(), so just add it and move on
_stmts.append(node)
continue
assign_type = node.assign_type()
_stmts, done = assign_type._get_filtered_stmts(base_node, node, _stmts, mystmt)
if done:
break
optional_assign = assign_type.optional_assign
if optional_assign and assign_type.parent_of(base_node):
# we are inside a loop, loop var assignment is hiding previous
# assignment
_stmts = [node]
_stmt_parents = [stmt.parent]
continue
if isinstance(assign_type, nodes.NamedExpr):
# If the NamedExpr is in an if statement we do some basic control flow inference
if_parent = _get_if_statement_ancestor(assign_type)
if if_parent:
# If the if statement is within another if statement we append the node
# to possible statements
if _get_if_statement_ancestor(if_parent):
optional_assign = False
_stmts.append(node)
_stmt_parents.append(stmt.parent)
# Else we assume that it will be evaluated
else:
_stmts = [node]
_stmt_parents = [stmt.parent]
else:
_stmts = [node]
_stmt_parents = [stmt.parent]
# XXX comment various branches below!!!
try:
pindex = _stmt_parents.index(stmt.parent)
except ValueError:
pass
else:
# we got a parent index, this means the currently visited node
# is at the same block level as a previously visited node
if _stmts[pindex].assign_type().parent_of(assign_type):
# both statements are not at the same block level
continue
# if currently visited node is following previously considered
# assignment and both are not exclusive, we can drop the
# previous one. For instance in the following code ::
#
# if a:
# x = 1
# else:
# x = 2
# print x
#
# we can't remove neither x = 1 nor x = 2 when looking for 'x'
# of 'print x'; while in the following ::
#
# x = 1
# x = 2
# print x
#
# we can remove x = 1 when we see x = 2
#
# moreover, on loop assignment types, assignment won't
# necessarily be done if the loop has no iteration, so we don't
# want to clear previous assignments if any (hence the test on
# optional_assign)
if not (optional_assign or nodes.are_exclusive(_stmts[pindex], node)):
del _stmt_parents[pindex]
del _stmts[pindex]
# If base_node and node are exclusive, then we can ignore node
if nodes.are_exclusive(base_node, node):
continue
# An AssignName node overrides previous assignments if:
# 1. node's statement always assigns
# 2. node and base_node are in the same block (i.e., has the same parent as base_node)
if isinstance(node, (nodes.NamedExpr, nodes.AssignName)):
if isinstance(stmt, nodes.ExceptHandler):
# If node's statement is an ExceptHandler, then it is the variable
# bound to the caught exception. If base_node is not contained within
# the exception handler block, node should override previous assignments;
# otherwise, node should be ignored, as an exception variable
# is local to the handler block.
if stmt.parent_of(base_node):
_stmts = []
_stmt_parents = []
else:
continue
elif not optional_assign and mystmt and stmt.parent is mystmt.parent:
_stmts = []
_stmt_parents = []
elif isinstance(node, nodes.DelName):
# Remove all previously stored assignments
_stmts = []
_stmt_parents = []
continue
# Add the new assignment
_stmts.append(node)
if isinstance(node, nodes.Arguments) or isinstance(
node.parent, nodes.Arguments
):
# Special case for _stmt_parents when node is a function parameter;
# in this case, stmt is the enclosing FunctionDef, which is what we
# want to add to _stmt_parents, not stmt.parent. This case occurs when
# node is an Arguments node (representing varargs or kwargs parameter),
# and when node.parent is an Arguments node (other parameters).
# See issue #180.
_stmt_parents.append(stmt)
else:
_stmt_parents.append(stmt.parent)
return _stmts
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