def _check_ignore_assignment_expr_suggestion(node: nodes.If,
name: Optional[str]) -> bool:
"""Return True if suggestion for assignment expr should be ignored.
E.g., in cases where a match statement would be a better fit
(multiple conditions).
"""
if isinstance(node.test, nodes.Compare):
next_if_node: Optional[nodes.If] = None
next_sibling = node.next_sibling()
if len(node.orelse) == 1 and isinstance(node.orelse[0], nodes.If):
# elif block
next_if_node = node.orelse[0]
elif isinstance(next_sibling, nodes.If):
# separate if block
next_if_node = next_sibling
if ( # pylint: disable=too-many-boolean-expressions
next_if_node is not None
and (isinstance(next_if_node.test, nodes.Compare)
and isinstance(next_if_node.test.left, nodes.Name)
and next_if_node.test.left.name == name
or isinstance(next_if_node.test, nodes.Name)
and next_if_node.test.name == name)):
return True
return False
def visit_if(self, node: nodes.If) -> None:
self._current_block.add_statement(node.test)
node.cfg_block = self._current_block
old_curr = self._current_block
# Handle "then" branch.
then_block = self._current_cfg.create_block(old_curr)
self._current_block = then_block
for child in node.body:
child.accept(self)
end_if = self._current_block
# Handle "else" branch.
if node.orelse == []:
end_else = old_curr
else:
else_block = self._current_cfg.create_block(old_curr)
self._current_block = else_block
for child in node.orelse:
child.accept(self)
end_else = self._current_block
after_if_block = self._current_cfg.create_block()
self._current_cfg.link_or_merge(end_if, after_if_block)
self._current_cfg.link_or_merge(end_else, after_if_block)
self._current_block = after_if_block
def _check_consider_using_assignment_expr(self, node: nodes.If) -> None:
"""Check if an assignment expression (walrus operator) can be used.
For example if an assignment is directly followed by an if statement:
>>> x = 2
>>> if x:
>>> ...
Can be replaced by:
>>> if (x := 2):
>>> ...
Note: Assignment expressions were added in Python 3.8
"""
# Check if `node.test` contains a `Name` node
node_name: Optional[nodes.Name] = None
if isinstance(node.test, nodes.Name):
node_name = node.test
elif (isinstance(node.test, nodes.UnaryOp) and node.test.op == "not"
and isinstance(node.test.operand, nodes.Name)):
node_name = node.test.operand
elif (isinstance(node.test, nodes.Compare)
and isinstance(node.test.left, nodes.Name)
and len(node.test.ops) == 1):
node_name = node.test.left
else:
return
# Make sure the previous node is an assignment to the same name
# used in `node.test`. Furthermore, ignore if assignment spans multiple lines.
prev_sibling = node.previous_sibling()
if CodeStyleChecker._check_prev_sibling_to_if_stmt(
prev_sibling, node_name.name):
# Check if match statement would be a better fit.
# I.e. multiple ifs that test the same name.
if CodeStyleChecker._check_ignore_assignment_expr_suggestion(
node, node_name.name):
return
# Build suggestion string. Check length of suggestion
# does not exceed max-line-length-suggestions
test_str = node.test.as_string().replace(
node_name.name,
f"({node_name.name} := {prev_sibling.value.as_string()})",
1,
)
suggestion = f"if {test_str}:"
if (node.col_offset is not None
and len(suggestion) + node.col_offset > self._max_length
or len(suggestion) > self._max_length):
return
self.add_message(
"consider-using-assignment-expr",
node=node_name,
args=(suggestion, ),
)
def visit_if(self, node: nodes.If) -> None:
body_ends_with_if = isinstance(
node.body[-1], nodes.If
) and self._has_no_else_clause(node.body[-1])
if node.has_elif_block() and body_ends_with_if:
self.add_message("confusing-consecutive-elif", node=node.orelse[0])