def __post_init__(self) -> None:
"""You are in a twisty little maze of passages."""
self.current_line = Line(mode=self.mode)
v = self.visit_stmt
Ø: Set[str] = set()
self.visit_assert_stmt = partial(v, keywords={"assert"}, parens={"assert", ","})
self.visit_if_stmt = partial(
v, keywords={"if", "else", "elif"}, parens={"if", "elif"}
)
self.visit_while_stmt = partial(v, keywords={"while", "else"}, parens={"while"})
self.visit_for_stmt = partial(v, keywords={"for", "else"}, parens={"for", "in"})
self.visit_try_stmt = partial(
v, keywords={"try", "except", "else", "finally"}, parens=Ø
)
self.visit_except_clause = partial(v, keywords={"except"}, parens=Ø)
self.visit_with_stmt = partial(v, keywords={"with"}, parens=Ø)
self.visit_funcdef = partial(v, keywords={"def"}, parens=Ø)
self.visit_classdef = partial(v, keywords={"class"}, parens=Ø)
self.visit_expr_stmt = partial(v, keywords=Ø, parens=ASSIGNMENTS)
self.visit_return_stmt = partial(v, keywords={"return"}, parens={"return"})
self.visit_import_from = partial(v, keywords=Ø, parens={"import"})
self.visit_del_stmt = partial(v, keywords=Ø, parens={"del"})
self.visit_async_funcdef = self.visit_async_stmt
self.visit_decorated = self.visit_decorators
# PEP 634
self.visit_match_stmt = self.visit_match_case
self.visit_case_block = self.visit_match_case
def _format_str_once(src_contents: str, *, mode: Mode) -> str:
src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions)
dst_contents = []
future_imports = get_future_imports(src_node)
if mode.target_versions:
versions = mode.target_versions
else:
versions = detect_target_versions(src_node,
future_imports=future_imports)
normalize_fmt_off(src_node, preview=mode.preview)
lines = LineGenerator(mode=mode)
elt = EmptyLineTracker(is_pyi=mode.is_pyi)
empty_line = Line(mode=mode)
after = 0
split_line_features = {
feature
for feature in
{Feature.TRAILING_COMMA_IN_CALL, Feature.TRAILING_COMMA_IN_DEF}
if supports_feature(versions, feature)
}
for current_line in lines.visit(src_node):
dst_contents.append(str(empty_line) * after)
before, after = elt.maybe_empty_lines(current_line)
dst_contents.append(str(empty_line) * before)
for line in transform_line(current_line,
mode=mode,
features=split_line_features):
dst_contents.append(str(line))
return "".join(dst_contents)
def standalone_comment_split(
line: Line, features: Collection[Feature] = ()
) -> Iterator[Line]:
"""Split standalone comments from the rest of the line."""
if not line.contains_standalone_comments(0):
raise CannotSplit("Line does not have any standalone comments")
current_line = Line(
mode=line.mode, depth=line.depth, inside_brackets=line.inside_brackets
)
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(
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)
if current_line:
yield current_line
def format_str(src_contents: str, *, mode: Mode) -> FileContent:
"""Reformat a string and return new contents.
`mode` determines formatting options, such as how many characters per line are
allowed. Example:
>>> import black
>>> print(black.format_str("def f(arg:str='')->None:...", mode=black.Mode()))
def f(arg: str = "") -> None:
...
A more complex example:
>>> print(
... black.format_str(
... "def f(arg:str='')->None: hey",
... mode=black.Mode(
... target_versions={black.TargetVersion.PY36},
... line_length=10,
... string_normalization=False,
... is_pyi=False,
... ),
... ),
... )
def f(
arg: str = '',
) -> None:
hey
"""
src_node = lib2to3_parse(src_contents.lstrip(), mode.target_versions)
dst_contents = []
future_imports = get_future_imports(src_node)
if mode.target_versions:
versions = mode.target_versions
else:
versions = detect_target_versions(src_node)
normalize_fmt_off(src_node)
lines = LineGenerator(
mode=mode,
remove_u_prefix="unicode_literals" in future_imports
or supports_feature(versions, Feature.UNICODE_LITERALS),
)
elt = EmptyLineTracker(is_pyi=mode.is_pyi)
empty_line = Line(mode=mode)
after = 0
split_line_features = {
feature
for feature in {Feature.TRAILING_COMMA_IN_CALL, Feature.TRAILING_COMMA_IN_DEF}
if supports_feature(versions, feature)
}
for current_line in lines.visit(src_node):
dst_contents.append(str(empty_line) * after)
before, after = elt.maybe_empty_lines(current_line)
dst_contents.append(str(empty_line) * before)
for line in transform_line(
current_line, mode=mode, features=split_line_features
):
dst_contents.append(str(line))
return "".join(dst_contents)
def bracket_split_build_line(
leaves: List[Leaf], original: Line, opening_bracket: Leaf, *, is_body: bool = False
) -> Line:
"""Return a new line with given `leaves` and respective comments from `original`.
If `is_body` is True, the result line is one-indented inside brackets and as such
has its first leaf's prefix normalized and a trailing comma added when expected.
"""
result = Line(mode=original.mode, depth=original.depth)
if is_body:
result.inside_brackets = True
result.depth += 1
if leaves:
# Since body is a new indent level, remove spurious leading whitespace.
normalize_prefix(leaves[0], inside_brackets=True)
# Ensure a trailing comma for imports and standalone function arguments, but
# be careful not to add one after any comments or within type annotations.
no_commas = (
original.is_def
and opening_bracket.value == "("
and not any(leaf.type == token.COMMA for leaf in leaves)
# In particular, don't add one within a parenthesized return annotation.
# Unfortunately the indicator we're in a return annotation (RARROW) may
# be defined directly in the parent node, the parent of the parent ...
# and so on depending on how complex the return annotation is.
# This isn't perfect and there's some false negatives but they are in
# contexts were a comma is actually fine.
and not any(
node.prev_sibling.type == RARROW
for node in (
leaves[0].parent,
getattr(leaves[0].parent, "parent", None),
)
if isinstance(node, Node) and isinstance(node.prev_sibling, Leaf)
)
)
if original.is_import or no_commas:
for i in range(len(leaves) - 1, -1, -1):
if leaves[i].type == STANDALONE_COMMENT:
continue
if leaves[i].type != token.COMMA:
new_comma = Leaf(token.COMMA, ",")
leaves.insert(i + 1, new_comma)
break
# Populate the line
for leaf in leaves:
result.append(leaf, preformatted=True)
for comment_after in original.comments_after(leaf):
result.append(comment_after, preformatted=True)
if is_body and should_split_line(result, opening_bracket):
result.should_split_rhs = True
return result
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(
line.mode, depth=line.depth, inside_brackets=line.inside_brackets
)
current_line.append(leaf)
def line(self, indent: int = 0) -> Iterator[Line]:
"""Generate a line.
If the line is empty, only emit if it makes sense.
If the line is too long, split it first and then generate.
If any lines were generated, set up a new current_line.
"""
if not self.current_line:
self.current_line.depth += indent
return # Line is empty, don't emit. Creating a new one unnecessary.
complete_line = self.current_line
self.current_line = Line(mode=self.mode, depth=complete_line.depth + indent)
yield complete_line
def bracket_split_build_line(leaves: List[Leaf],
original: Line,
opening_bracket: Leaf,
*,
is_body: bool = False) -> Line:
"""Return a new line with given `leaves` and respective comments from `original`.
If `is_body` is True, the result line is one-indented inside brackets and as such
has its first leaf's prefix normalized and a trailing comma added when expected.
"""
result = Line(mode=original.mode, depth=original.depth)
if is_body:
result.inside_brackets = True
result.depth += 1
if leaves:
# Since body is a new indent level, remove spurious leading whitespace.
normalize_prefix(leaves[0], inside_brackets=True)
# Ensure a trailing comma for imports and standalone function arguments, but
# be careful not to add one after any comments or within type annotations.
no_commas = (original.is_def and opening_bracket.value == "("
and not any(leaf.type == token.COMMA
for leaf in leaves))
if original.is_import or no_commas:
for i in range(len(leaves) - 1, -1, -1):
if leaves[i].type == STANDALONE_COMMENT:
continue
if leaves[i].type != token.COMMA and not original.is_import:
new_comma = Leaf(token.COMMA, ",")
leaves.insert(i + 1, new_comma)
break
# Populate the line
for leaf in leaves:
result.append(leaf, preformatted=True)
for comment_after in original.comments_after(leaf):
result.append(comment_after, preformatted=True)
if is_body and should_split_line(result, opening_bracket):
result.should_split_rhs = True
return result
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
