def delimiter_split(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
"""Split according to delimiters of the highest priority.
If the appropriate Features are given, the split will add trailing commas
also in function signatures and calls that contain `*` and `**`.
"""
try:
last_leaf = line.leaves[-1]
except IndexError:
raise CannotSplit("Line empty") from None
bt = line.bracket_tracker
try:
delimiter_priority = bt.max_delimiter_priority(exclude={id(last_leaf)})
except ValueError:
raise CannotSplit("No delimiters found") from None
if delimiter_priority == DOT_PRIORITY:
if bt.delimiter_count_with_priority(delimiter_priority) == 1:
raise CannotSplit("Splitting a single attribute from its owner looks wrong")
current_line = Line(
mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
)
lowest_depth = sys.maxsize
trailing_comma_safe = True
def append_to_line(leaf: Leaf) -> Iterator[Line]:
"""Append `leaf` to current line or to new line if appending impossible."""
nonlocal current_line
try:
current_line.append_safe(leaf, preformatted=True)
except ValueError:
yield current_line
current_line = Line(
mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
)
current_line.append(leaf)
for leaf in line.leaves:
yield from append_to_line(leaf)
for comment_after in line.comments_after(leaf):
yield from append_to_line(comment_after)
lowest_depth = min(lowest_depth, leaf.bracket_depth)
if leaf.bracket_depth == lowest_depth:
if is_vararg(leaf, within={syms.typedargslist}):
trailing_comma_safe = (
trailing_comma_safe and Feature.TRAILING_COMMA_IN_DEF in features
)
elif is_vararg(leaf, within={syms.arglist, syms.argument}):
trailing_comma_safe = (
trailing_comma_safe and Feature.TRAILING_COMMA_IN_CALL in features
)
leaf_priority = bt.delimiters.get(id(leaf))
if leaf_priority == delimiter_priority:
yield current_line
current_line = Line(
mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
)
if current_line:
if (
trailing_comma_safe
and delimiter_priority == COMMA_PRIORITY
and current_line.leaves[-1].type != token.COMMA
and current_line.leaves[-1].type != STANDALONE_COMMENT
):
new_comma = Leaf(token.COMMA, ",")
current_line.append(new_comma)
yield current_line
def is_split_before_delimiter(leaf: Leaf, previous: Optional[Leaf] = None) -> Priority:
"""Return the priority of the `leaf` delimiter, given a line break before it.
The delimiter priorities returned here are from those delimiters that would
cause a line break before themselves.
Higher numbers are higher priority.
"""
if is_vararg(leaf, within=VARARGS_PARENTS | UNPACKING_PARENTS):
# * and ** might also be MATH_OPERATORS but in this case they are not.
# Don't treat them as a delimiter.
return 0
if (
leaf.type == token.DOT
and leaf.parent
and leaf.parent.type not in {syms.import_from, syms.dotted_name}
and (previous is None or previous.type in CLOSING_BRACKETS)
):
return DOT_PRIORITY
if (
leaf.type in MATH_OPERATORS
and leaf.parent
and leaf.parent.type not in {syms.factor, syms.star_expr}
):
return MATH_PRIORITIES[leaf.type]
if leaf.type in COMPARATORS:
return COMPARATOR_PRIORITY
if (
leaf.type == token.STRING
and previous is not None
and previous.type == token.STRING
):
return STRING_PRIORITY
if leaf.type not in {token.NAME, token.ASYNC}:
return 0
if (
leaf.value == "for"
and leaf.parent
and leaf.parent.type in {syms.comp_for, syms.old_comp_for}
or leaf.type == token.ASYNC
):
if (
not isinstance(leaf.prev_sibling, Leaf)
or leaf.prev_sibling.value != "async"
):
return COMPREHENSION_PRIORITY
if (
leaf.value == "if"
and leaf.parent
and leaf.parent.type in {syms.comp_if, syms.old_comp_if}
):
return COMPREHENSION_PRIORITY
if leaf.value in {"if", "else"} and leaf.parent and leaf.parent.type == syms.test:
return TERNARY_PRIORITY
if leaf.value == "is":
return COMPARATOR_PRIORITY
if (
leaf.value == "in"
and leaf.parent
and leaf.parent.type in {syms.comp_op, syms.comparison}
and not (
previous is not None
and previous.type == token.NAME
and previous.value == "not"
)
):
return COMPARATOR_PRIORITY
if (
leaf.value == "not"
and leaf.parent
and leaf.parent.type == syms.comp_op
and not (
previous is not None
and previous.type == token.NAME
and previous.value == "is"
)
):
return COMPARATOR_PRIORITY
if leaf.value in LOGIC_OPERATORS and leaf.parent:
return LOGIC_PRIORITY
return 0