def has_magic_trailing_comma(
self, closing: Leaf, ensure_removable: bool = False
) -> bool:
"""Return True if we have a magic trailing comma, that is when:
- there's a trailing comma here
- it's not a one-tuple
Additionally, if ensure_removable:
- it's not from square bracket indexing
"""
if not (
closing.type in CLOSING_BRACKETS
and self.leaves
and self.leaves[-1].type == token.COMMA
):
return False
if closing.type == token.RBRACE:
return True
if closing.type == token.RSQB:
if not ensure_removable:
return True
comma = self.leaves[-1]
return bool(comma.parent and comma.parent.type == syms.listmaker)
if self.is_import:
return True
if closing.opening_bracket is not None and not is_one_tuple_between(
closing.opening_bracket, closing, self.leaves
):
return True
return False
def generate_trailers_to_omit(line: Line, line_length: int) -> Iterator[Set[LeafID]]:
"""Generate sets of closing bracket IDs that should be omitted in a RHS.
Brackets can be omitted if the entire trailer up to and including
a preceding closing bracket fits in one line.
Yielded sets are cumulative (contain results of previous yields, too). First
set is empty, unless the line should explode, in which case bracket pairs until
the one that needs to explode are omitted.
"""
omit: Set[LeafID] = set()
if not line.magic_trailing_comma:
yield omit
length = 4 * line.depth
opening_bracket: Optional[Leaf] = None
closing_bracket: Optional[Leaf] = None
inner_brackets: Set[LeafID] = set()
for index, leaf, leaf_length in line.enumerate_with_length(reversed=True):
length += leaf_length
if length > line_length:
break
has_inline_comment = leaf_length > len(leaf.value) + len(leaf.prefix)
if leaf.type == STANDALONE_COMMENT or has_inline_comment:
break
if opening_bracket:
if leaf is opening_bracket:
opening_bracket = None
elif leaf.type in CLOSING_BRACKETS:
prev = line.leaves[index - 1] if index > 0 else None
if (
prev
and prev.type == token.COMMA
and leaf.opening_bracket is not None
and not is_one_tuple_between(
leaf.opening_bracket, leaf, line.leaves
)
):
# Never omit bracket pairs with trailing commas.
# We need to explode on those.
break
inner_brackets.add(id(leaf))
elif leaf.type in CLOSING_BRACKETS:
prev = line.leaves[index - 1] if index > 0 else None
if prev and prev.type in OPENING_BRACKETS:
# Empty brackets would fail a split so treat them as "inner"
# brackets (e.g. only add them to the `omit` set if another
# pair of brackets was good enough.
inner_brackets.add(id(leaf))
continue
if closing_bracket:
omit.add(id(closing_bracket))
omit.update(inner_brackets)
inner_brackets.clear()
yield omit
if (
prev
and prev.type == token.COMMA
and leaf.opening_bracket is not None
and not is_one_tuple_between(leaf.opening_bracket, leaf, line.leaves)
):
# Never omit bracket pairs with trailing commas.
# We need to explode on those.
break
if leaf.value:
opening_bracket = leaf.opening_bracket
closing_bracket = leaf
