def normalize_invisible_parens(node: Node, parens_after: Set[str], *,
preview: bool) -> None:
"""Make existing optional parentheses invisible or create new ones.
`parens_after` is a set of string leaf values immediately after which parens
should be put.
Standardizes on visible parentheses for single-element tuples, and keeps
existing visible parentheses for other tuples and generator expressions.
"""
for pc in list_comments(node.prefix, is_endmarker=False, preview=preview):
if pc.value in FMT_OFF:
# This `node` has a prefix with `# fmt: off`, don't mess with parens.
return
check_lpar = False
for index, child in enumerate(list(node.children)):
# Fixes a bug where invisible parens are not properly stripped from
# assignment statements that contain type annotations.
if isinstance(child, Node) and child.type == syms.annassign:
normalize_invisible_parens(child,
parens_after=parens_after,
preview=preview)
# Add parentheses around long tuple unpacking in assignments.
if (index == 0 and isinstance(child, Node)
and child.type == syms.testlist_star_expr):
check_lpar = True
if check_lpar:
if child.type == syms.atom:
if maybe_make_parens_invisible_in_atom(
child,
parent=node,
preview=preview,
):
wrap_in_parentheses(node, child, visible=False)
elif is_one_tuple(child):
wrap_in_parentheses(node, child, visible=True)
elif node.type == syms.import_from:
# "import from" nodes store parentheses directly as part of
# the statement
if is_lpar_token(child):
assert is_rpar_token(node.children[-1])
# make parentheses invisible
child.value = ""
node.children[-1].value = ""
elif child.type != token.STAR:
# insert invisible parentheses
node.insert_child(index, Leaf(token.LPAR, ""))
node.append_child(Leaf(token.RPAR, ""))
break
elif not (isinstance(child, Leaf) and is_multiline_string(child)):
wrap_in_parentheses(node, child, visible=False)
check_lpar = isinstance(child, Leaf) and child.value in parens_after
def visit_factor(self, node: Node) -> Iterator[Line]:
"""Force parentheses between a unary op and a binary power:
-2 ** 8 -> -(2 ** 8)
"""
_operator, operand = node.children
if (operand.type == syms.power and len(operand.children) == 3
and operand.children[1].type == token.DOUBLESTAR):
lpar = Leaf(token.LPAR, "(")
rpar = Leaf(token.RPAR, ")")
index = operand.remove() or 0
node.insert_child(index, Node(syms.atom, [lpar, operand, rpar]))
yield from self.visit_default(node)
def wrap_in_parentheses(parent: Node, child: LN, *, visible: bool = True) -> None:
"""Wrap `child` in parentheses.
This replaces `child` with an atom holding the parentheses and the old
child. That requires moving the prefix.
If `visible` is False, the leaves will be valueless (and thus invisible).
"""
lpar = Leaf(token.LPAR, "(" if visible else "")
rpar = Leaf(token.RPAR, ")" if visible else "")
prefix = child.prefix
child.prefix = ""
index = child.remove() or 0
new_child = Node(syms.atom, [lpar, child, rpar])
new_child.prefix = prefix
parent.insert_child(index, new_child)