"""
Generating lines of code.
"""
-from functools import partial, wraps
import sys
-from typing import Collection, Iterator, List, Optional, Set, Union
-
-from black.nodes import WHITESPACE, RARROW, STATEMENT, STANDALONE_COMMENT
-from black.nodes import ASSIGNMENTS, OPENING_BRACKETS, CLOSING_BRACKETS
-from black.nodes import Visitor, syms, is_arith_like, ensure_visible
-from black.nodes import is_docstring, is_empty_tuple, is_one_tuple, is_one_tuple_between
-from black.nodes import is_name_token, is_lpar_token, is_rpar_token
-from black.nodes import is_walrus_assignment, is_yield, is_vararg, is_multiline_string
-from black.nodes import is_stub_suite, is_stub_body, is_atom_with_invisible_parens
-from black.nodes import wrap_in_parentheses
-from black.brackets import max_delimiter_priority_in_atom
-from black.brackets import DOT_PRIORITY, COMMA_PRIORITY
-from black.lines import Line, line_to_string, is_line_short_enough
-from black.lines import can_omit_invisible_parens, can_be_split, append_leaves
-from black.comments import generate_comments, list_comments, FMT_OFF
+from enum import Enum, auto
+from functools import partial, wraps
+from typing import Collection, Iterator, List, Optional, Set, Union, cast
+
+from black.brackets import (
+ COMMA_PRIORITY,
+ DOT_PRIORITY,
+ get_leaves_inside_matching_brackets,
+ max_delimiter_priority_in_atom,
+)
+from black.comments import FMT_OFF, generate_comments, list_comments
+from black.lines import (
+ Line,
+ append_leaves,
+ can_be_split,
+ can_omit_invisible_parens,
+ is_line_short_enough,
+ line_to_string,
+)
+from black.mode import Feature, Mode, Preview
+from black.nodes import (
+ ASSIGNMENTS,
+ CLOSING_BRACKETS,
+ OPENING_BRACKETS,
+ RARROW,
+ STANDALONE_COMMENT,
+ STATEMENT,
+ WHITESPACE,
+ Visitor,
+ ensure_visible,
+ is_arith_like,
+ is_atom_with_invisible_parens,
+ is_docstring,
+ is_empty_tuple,
+ is_lpar_token,
+ is_multiline_string,
+ is_name_token,
+ is_one_sequence_between,
+ is_one_tuple,
+ is_rpar_token,
+ is_stub_body,
+ is_stub_suite,
+ is_vararg,
+ is_walrus_assignment,
+ is_yield,
+ syms,
+ wrap_in_parentheses,
+)
from black.numerics import normalize_numeric_literal
-from black.strings import get_string_prefix, fix_docstring
-from black.strings import normalize_string_prefix, normalize_string_quotes
-from black.trans import Transformer, CannotTransform, StringMerger, StringSplitter
-from black.trans import StringParenWrapper, StringParenStripper, hug_power_op
-from black.mode import Mode, Feature, Preview
-
-from blib2to3.pytree import Node, Leaf
+from black.strings import (
+ fix_docstring,
+ get_string_prefix,
+ normalize_string_prefix,
+ normalize_string_quotes,
+)
+from black.trans import (
+ CannotTransform,
+ StringMerger,
+ StringParenStripper,
+ StringParenWrapper,
+ StringSplitter,
+ Transformer,
+ hug_power_op,
+)
from blib2to3.pgen2 import token
-
+from blib2to3.pytree import Leaf, Node
# types
LeafID = int
"""Default `visit_*()` implementation. Recurses to children of `node`."""
if isinstance(node, Leaf):
any_open_brackets = self.current_line.bracket_tracker.any_open_brackets()
- for comment in generate_comments(node):
+ for comment in generate_comments(node, preview=self.mode.preview):
if any_open_brackets:
# any comment within brackets is subject to splitting
self.current_line.append(comment)
`parens` holds a set of string leaf values immediately after which
invisible parens should be put.
"""
- normalize_invisible_parens(node, parens_after=parens)
+ normalize_invisible_parens(node, parens_after=parens, preview=self.mode.preview)
for child in node.children:
if is_name_token(child) and child.value in keywords:
yield from self.line()
yield from self.visit(child)
+ def visit_funcdef(self, node: Node) -> Iterator[Line]:
+ """Visit function definition."""
+ if Preview.annotation_parens not in self.mode:
+ yield from self.visit_stmt(node, keywords={"def"}, parens=set())
+ else:
+ yield from self.line()
+
+ # Remove redundant brackets around return type annotation.
+ is_return_annotation = False
+ for child in node.children:
+ if child.type == token.RARROW:
+ is_return_annotation = True
+ elif is_return_annotation:
+ if child.type == syms.atom and child.children[0].type == token.LPAR:
+ if maybe_make_parens_invisible_in_atom(
+ child,
+ parent=node,
+ remove_brackets_around_comma=False,
+ ):
+ wrap_in_parentheses(node, child, visible=False)
+ else:
+ wrap_in_parentheses(node, child, visible=False)
+ is_return_annotation = False
+
+ for child in node.children:
+ yield from self.visit(child)
+
def visit_match_case(self, node: Node) -> Iterator[Line]:
"""Visit either a match or case statement."""
- normalize_invisible_parens(node, parens_after=set())
+ normalize_invisible_parens(node, parens_after=set(), preview=self.mode.preview)
yield from self.line()
for child in node.children:
for child in children:
yield from self.visit(child)
- if child.type == token.ASYNC:
+ if child.type == token.ASYNC or child.type == STANDALONE_COMMENT:
+ # STANDALONE_COMMENT happens when `# fmt: skip` is applied on the async
+ # line.
break
internal_stmt = next(children)
):
wrap_in_parentheses(node, leaf)
+ if Preview.remove_redundant_parens in self.mode:
+ remove_await_parens(node)
+
yield from self.visit_default(node)
def visit_SEMI(self, leaf: Leaf) -> Iterator[Line]:
if is_docstring(leaf) and "\\\n" not in leaf.value:
# We're ignoring docstrings with backslash newline escapes because changing
# indentation of those changes the AST representation of the code.
- docstring = normalize_string_prefix(leaf.value)
+ if Preview.normalize_docstring_quotes_and_prefixes_properly in self.mode:
+ # There was a bug where --skip-string-normalization wouldn't stop us
+ # from normalizing docstring prefixes. To maintain stability, we can
+ # only address this buggy behaviour while the preview style is enabled.
+ if self.mode.string_normalization:
+ docstring = normalize_string_prefix(leaf.value)
+ # visit_default() does handle string normalization for us, but
+ # since this method acts differently depending on quote style (ex.
+ # see padding logic below), there's a possibility for unstable
+ # formatting as visit_default() is called *after*. To avoid a
+ # situation where this function formats a docstring differently on
+ # the second pass, normalize it early.
+ docstring = normalize_string_quotes(docstring)
+ else:
+ docstring = leaf.value
+ else:
+ # ... otherwise, we'll keep the buggy behaviour >.<
+ docstring = normalize_string_prefix(leaf.value)
prefix = get_string_prefix(docstring)
docstring = docstring[len(prefix) :] # Remove the prefix
quote_char = docstring[0]
quote_len = 1 if docstring[1] != quote_char else 3
docstring = docstring[quote_len:-quote_len]
docstring_started_empty = not docstring
+ indent = " " * 4 * self.current_line.depth
if is_multiline_string(leaf):
- indent = " " * 4 * self.current_line.depth
docstring = fix_docstring(docstring, indent)
else:
docstring = docstring.strip()
# We could enforce triple quotes at this point.
quote = quote_char * quote_len
- leaf.value = prefix + quote + docstring + quote
+
+ # It's invalid to put closing single-character quotes on a new line.
+ if Preview.long_docstring_quotes_on_newline in self.mode and quote_len == 3:
+ # We need to find the length of the last line of the docstring
+ # to find if we can add the closing quotes to the line without
+ # exceeding the maximum line length.
+ # If docstring is one line, we don't put the closing quotes on a
+ # separate line because it looks ugly (#3320).
+ lines = docstring.splitlines()
+ last_line_length = len(lines[-1]) if docstring else 0
+
+ # If adding closing quotes would cause the last line to exceed
+ # the maximum line length then put a line break before the
+ # closing quotes
+ if (
+ len(lines) > 1
+ and last_line_length + quote_len > self.mode.line_length
+ ):
+ leaf.value = prefix + quote + docstring + "\n" + indent + quote
+ else:
+ leaf.value = prefix + quote + docstring + quote
+ else:
+ leaf.value = prefix + quote + docstring + quote
yield from self.visit_default(leaf)
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)
+ if self.mode.preview:
+ self.visit_except_clause = partial(
+ v, keywords={"except"}, parens={"except"}
+ )
+ self.visit_with_stmt = partial(v, keywords={"with"}, parens={"with"})
+ else:
+ self.visit_except_clause = partial(v, keywords={"except"}, parens=Ø)
+ self.visit_with_stmt = partial(v, keywords={"with"}, 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"})
yield line
+class _BracketSplitComponent(Enum):
+ head = auto()
+ body = auto()
+ tail = auto()
+
+
def left_hand_split(line: Line, _features: Collection[Feature] = ()) -> Iterator[Line]:
"""Split line into many lines, starting with the first matching bracket pair.
current_leaves is body_leaves
and leaf.type in CLOSING_BRACKETS
and leaf.opening_bracket is matching_bracket
+ and isinstance(matching_bracket, Leaf)
):
+ ensure_visible(leaf)
+ ensure_visible(matching_bracket)
current_leaves = tail_leaves if body_leaves else head_leaves
current_leaves.append(leaf)
if current_leaves is head_leaves:
if not matching_bracket:
raise CannotSplit("No brackets found")
- head = bracket_split_build_line(head_leaves, line, matching_bracket)
- body = bracket_split_build_line(body_leaves, line, matching_bracket, is_body=True)
- tail = bracket_split_build_line(tail_leaves, line, matching_bracket)
+ head = bracket_split_build_line(
+ head_leaves, line, matching_bracket, component=_BracketSplitComponent.head
+ )
+ body = bracket_split_build_line(
+ body_leaves, line, matching_bracket, component=_BracketSplitComponent.body
+ )
+ tail = bracket_split_build_line(
+ tail_leaves, line, matching_bracket, component=_BracketSplitComponent.tail
+ )
bracket_split_succeeded_or_raise(head, body, tail)
for result in (head, body, tail):
if result:
tail_leaves.reverse()
body_leaves.reverse()
head_leaves.reverse()
- head = bracket_split_build_line(head_leaves, line, opening_bracket)
- body = bracket_split_build_line(body_leaves, line, opening_bracket, is_body=True)
- tail = bracket_split_build_line(tail_leaves, line, opening_bracket)
+ head = bracket_split_build_line(
+ head_leaves, line, opening_bracket, component=_BracketSplitComponent.head
+ )
+ body = bracket_split_build_line(
+ body_leaves, line, opening_bracket, component=_BracketSplitComponent.body
+ )
+ tail = bracket_split_build_line(
+ tail_leaves, line, opening_bracket, component=_BracketSplitComponent.tail
+ )
bracket_split_succeeded_or_raise(head, body, tail)
if (
Feature.FORCE_OPTIONAL_PARENTHESES not in features
# there are no standalone comments in the body
and not body.contains_standalone_comments(0)
# and we can actually remove the parens
- and can_omit_invisible_parens(body, line_length, omit_on_explode=omit)
+ and can_omit_invisible_parens(body, line_length)
):
omit = {id(closing_bracket), *omit}
try:
def bracket_split_build_line(
- leaves: List[Leaf], original: Line, opening_bracket: Leaf, *, is_body: bool = False
+ leaves: List[Leaf],
+ original: Line,
+ opening_bracket: Leaf,
+ *,
+ component: _BracketSplitComponent,
) -> 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.
+ If it's the head component, brackets will be tracked so trailing commas are
+ respected.
+
+ If it's the body component, 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:
+ if component is _BracketSplitComponent.body:
result.inside_brackets = True
result.depth += 1
if leaves:
leaves.insert(i + 1, new_comma)
break
+ leaves_to_track: Set[LeafID] = set()
+ if (
+ Preview.handle_trailing_commas_in_head in original.mode
+ and component is _BracketSplitComponent.head
+ ):
+ leaves_to_track = get_leaves_inside_matching_brackets(leaves)
# Populate the line
for leaf in leaves:
- result.append(leaf, preformatted=True)
+ result.append(
+ leaf,
+ preformatted=True,
+ track_bracket=id(leaf) in leaves_to_track,
+ )
for comment_after in original.comments_after(leaf):
result.append(comment_after, preformatted=True)
- if is_body and should_split_line(result, opening_bracket):
+ if component is _BracketSplitComponent.body and should_split_line(
+ result, opening_bracket
+ ):
result.should_split_rhs = True
return result
@wraps(split_func)
def split_wrapper(line: Line, features: Collection[Feature] = ()) -> Iterator[Line]:
- for line in split_func(line, features):
- normalize_prefix(line.leaves[0], inside_brackets=True)
- yield line
+ for split_line in split_func(line, features):
+ normalize_prefix(split_line.leaves[0], inside_brackets=True)
+ yield split_line
return split_wrapper
leaf.prefix = ""
-def normalize_invisible_parens(node: Node, parens_after: Set[str]) -> None:
+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
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):
+ 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
# 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)
+ normalize_invisible_parens(
+ child, parens_after=parens_after, preview=preview
+ )
# Add parentheses around long tuple unpacking in assignments.
if (
check_lpar = True
if check_lpar:
- if child.type == syms.atom:
- if maybe_make_parens_invisible_in_atom(child, parent=node):
+ if (
+ preview
+ and child.type == syms.atom
+ and node.type == syms.for_stmt
+ and isinstance(child.prev_sibling, Leaf)
+ and child.prev_sibling.type == token.NAME
+ and child.prev_sibling.value == "for"
+ ):
+ if maybe_make_parens_invisible_in_atom(
+ child,
+ parent=node,
+ remove_brackets_around_comma=True,
+ ):
+ wrap_in_parentheses(node, child, visible=False)
+ elif preview and isinstance(child, Node) and node.type == syms.with_stmt:
+ remove_with_parens(child, node)
+ elif child.type == syms.atom:
+ if maybe_make_parens_invisible_in_atom(
+ child,
+ parent=node,
+ ):
wrap_in_parentheses(node, child, visible=False)
elif is_one_tuple(child):
wrap_in_parentheses(node, child, visible=True)
node.insert_child(index, Leaf(token.LPAR, ""))
node.append_child(Leaf(token.RPAR, ""))
break
+ elif (
+ index == 1
+ and child.type == token.STAR
+ and node.type == syms.except_clause
+ ):
+ # In except* (PEP 654), the star is actually part of
+ # of the keyword. So we need to skip the insertion of
+ # invisible parentheses to work more precisely.
+ continue
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
+ comma_check = child.type == token.COMMA if preview else False
+
+ check_lpar = isinstance(child, Leaf) and (
+ child.value in parens_after or comma_check
+ )
+
+
+def remove_await_parens(node: Node) -> None:
+ if node.children[0].type == token.AWAIT and len(node.children) > 1:
+ if (
+ node.children[1].type == syms.atom
+ and node.children[1].children[0].type == token.LPAR
+ ):
+ if maybe_make_parens_invisible_in_atom(
+ node.children[1],
+ parent=node,
+ remove_brackets_around_comma=True,
+ ):
+ wrap_in_parentheses(node, node.children[1], visible=False)
+
+ # Since await is an expression we shouldn't remove
+ # brackets in cases where this would change
+ # the AST due to operator precedence.
+ # Therefore we only aim to remove brackets around
+ # power nodes that aren't also await expressions themselves.
+ # https://peps.python.org/pep-0492/#updated-operator-precedence-table
+ # N.B. We've still removed any redundant nested brackets though :)
+ opening_bracket = cast(Leaf, node.children[1].children[0])
+ closing_bracket = cast(Leaf, node.children[1].children[-1])
+ bracket_contents = cast(Node, node.children[1].children[1])
+ if bracket_contents.type != syms.power:
+ ensure_visible(opening_bracket)
+ ensure_visible(closing_bracket)
+ elif (
+ bracket_contents.type == syms.power
+ and bracket_contents.children[0].type == token.AWAIT
+ ):
+ ensure_visible(opening_bracket)
+ ensure_visible(closing_bracket)
+ # If we are in a nested await then recurse down.
+ remove_await_parens(bracket_contents)
+
+
+def remove_with_parens(node: Node, parent: Node) -> None:
+ """Recursively hide optional parens in `with` statements."""
+ # Removing all unnecessary parentheses in with statements in one pass is a tad
+ # complex as different variations of bracketed statements result in pretty
+ # different parse trees:
+ #
+ # with (open("file")) as f: # this is an asexpr_test
+ # ...
+ #
+ # with (open("file") as f): # this is an atom containing an
+ # ... # asexpr_test
+ #
+ # with (open("file")) as f, (open("file")) as f: # this is asexpr_test, COMMA,
+ # ... # asexpr_test
+ #
+ # with (open("file") as f, open("file") as f): # an atom containing a
+ # ... # testlist_gexp which then
+ # # contains multiple asexpr_test(s)
+ if node.type == syms.atom:
+ if maybe_make_parens_invisible_in_atom(
+ node,
+ parent=parent,
+ remove_brackets_around_comma=True,
+ ):
+ wrap_in_parentheses(parent, node, visible=False)
+ if isinstance(node.children[1], Node):
+ remove_with_parens(node.children[1], node)
+ elif node.type == syms.testlist_gexp:
+ for child in node.children:
+ if isinstance(child, Node):
+ remove_with_parens(child, node)
+ elif node.type == syms.asexpr_test and not any(
+ leaf.type == token.COLONEQUAL for leaf in node.leaves()
+ ):
+ if maybe_make_parens_invisible_in_atom(
+ node.children[0],
+ parent=node,
+ remove_brackets_around_comma=True,
+ ):
+ wrap_in_parentheses(node, node.children[0], visible=False)
-def maybe_make_parens_invisible_in_atom(node: LN, parent: LN) -> bool:
+def maybe_make_parens_invisible_in_atom(
+ node: LN,
+ parent: LN,
+ remove_brackets_around_comma: bool = False,
+) -> bool:
"""If it's safe, make the parens in the atom `node` invisible, recursively.
Additionally, remove repeated, adjacent invisible parens from the atom `node`
as they are redundant.
Returns whether the node should itself be wrapped in invisible parentheses.
-
"""
-
if (
node.type != syms.atom
or is_empty_tuple(node)
or is_one_tuple(node)
or (is_yield(node) and parent.type != syms.expr_stmt)
- or max_delimiter_priority_in_atom(node) >= COMMA_PRIORITY
+ or (
+ # This condition tries to prevent removing non-optional brackets
+ # around a tuple, however, can be a bit overzealous so we provide
+ # and option to skip this check for `for` and `with` statements.
+ not remove_brackets_around_comma
+ and max_delimiter_priority_in_atom(node) >= COMMA_PRIORITY
+ )
):
return False
# make parentheses invisible
first.value = ""
last.value = ""
- maybe_make_parens_invisible_in_atom(middle, parent=parent)
+ maybe_make_parens_invisible_in_atom(
+ middle,
+ parent=parent,
+ remove_brackets_around_comma=remove_brackets_around_comma,
+ )
if is_atom_with_invisible_parens(middle):
# Strip the invisible parens from `middle` by replacing
prev
and prev.type == token.COMMA
and leaf.opening_bracket is not None
- and not is_one_tuple_between(
+ and not is_one_sequence_between(
leaf.opening_bracket, leaf, line.leaves
)
):
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)
+ and not is_one_sequence_between(leaf.opening_bracket, leaf, line.leaves)
):
# Never omit bracket pairs with trailing commas.
# We need to explode on those.
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