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Wrap multiple context managers in parentheses when targeting Python 3.9+ (#3489)

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Yilei "Dolee" Yang 2023-01-20 04:14:05 -08:00 committed by GitHub
parent 18fb88486d
commit 91e1e1328a
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GPG Key ID: 4AEE18F83AFDEB23
11 changed files with 416 additions and 21 deletions
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1
CHANGES.md
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@ -35,6 +35,7 @@
- Fix two crashes in preview style involving edge cases with docstrings (#3451)
- Exclude string type annotations from improved string processing; fix crash when the
return type annotation is stringified and spans across multiple lines (#3462)
- Wrap multiple context managers in parentheses when targeting Python 3.9+ (#3489)
- Fix several crashes in preview style with walrus operators used in `with` statements
or tuples (#3473)

28
src/black/__init__.py
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@ -1096,8 +1096,13 @@ def _format_str_once(src_contents: str, *, mode: Mode) -> str:
future_imports = get_future_imports(src_node)
versions = detect_target_versions(src_node, future_imports=future_imports)
context_manager_features = {
feature
for feature in {Feature.PARENTHESIZED_CONTEXT_MANAGERS}
if supports_feature(versions, feature)
}
normalize_fmt_off(src_node, preview=mode.preview)
lines = LineGenerator(mode=mode)
lines = LineGenerator(mode=mode, features=context_manager_features)
elt = EmptyLineTracker(mode=mode)
split_line_features = {
feature
@ -1159,6 +1164,10 @@ def get_features_used( # noqa: C901
- relaxed decorator syntax;
- usage of __future__ flags (annotations);
- print / exec statements;
- parenthesized context managers;
- match statements;
- except* clause;
- variadic generics;
"""
features: Set[Feature] = set()
if future_imports:
@ -1234,6 +1243,23 @@ def get_features_used( # noqa: C901
):
features.add(Feature.ANN_ASSIGN_EXTENDED_RHS)
elif (
n.type == syms.with_stmt
and len(n.children) > 2
and n.children[1].type == syms.atom
):
atom_children = n.children[1].children
if (
len(atom_children) == 3
and atom_children[0].type == token.LPAR
and atom_children[1].type == syms.testlist_gexp
and atom_children[2].type == token.RPAR
):
features.add(Feature.PARENTHESIZED_CONTEXT_MANAGERS)
elif n.type == syms.match_stmt:
features.add(Feature.PATTERN_MATCHING)
elif (
n.type == syms.except_clause
and len(n.children) >= 2

101
src/black/linegen.py
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@ -90,8 +90,9 @@ class LineGenerator(Visitor[Line]):
in ways that will no longer stringify to valid Python code on the tree.
"""
def __init__(self, mode: Mode) -> None:
def __init__(self, mode: Mode, features: Collection[Feature]) -> None:
self.mode = mode
self.features = features
self.current_line: Line
self.__post_init__()
@ -191,7 +192,9 @@ def visit_stmt(
`parens` holds a set of string leaf values immediately after which
invisible parens should be put.
"""
normalize_invisible_parens(node, parens_after=parens, preview=self.mode.preview)
normalize_invisible_parens(
node, parens_after=parens, mode=self.mode, features=self.features
)
for child in node.children:
if is_name_token(child) and child.value in keywords:
yield from self.line()
@ -244,7 +247,9 @@ def visit_funcdef(self, node: Node) -> Iterator[Line]:
def visit_match_case(self, node: Node) -> Iterator[Line]:
"""Visit either a match or case statement."""
normalize_invisible_parens(node, parens_after=set(), preview=self.mode.preview)
normalize_invisible_parens(
node, parens_after=set(), mode=self.mode, features=self.features
)
yield from self.line()
for child in node.children:
@ -1090,7 +1095,7 @@ def normalize_prefix(leaf: Leaf, *, inside_brackets: bool) -> None:
def normalize_invisible_parens(
node: Node, parens_after: Set[str], *, preview: bool
node: Node, parens_after: Set[str], *, mode: Mode, features: Collection[Feature]
) -> None:
"""Make existing optional parentheses invisible or create new ones.
@ -1100,17 +1105,24 @@ def normalize_invisible_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, preview=preview):
for pc in list_comments(node.prefix, is_endmarker=False, preview=mode.preview):
if pc.value in FMT_OFF:
# This `node` has a prefix with `# fmt: off`, don't mess with parens.
return
# The multiple context managers grammar has a different pattern, thus this is
# separate from the for-loop below. This possibly wraps them in invisible parens,
# and later will be removed in remove_with_parens when needed.
if node.type == syms.with_stmt:
_maybe_wrap_cms_in_parens(node, mode, features)
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
child, parens_after=parens_after, mode=mode, features=features
)
# Add parentheses around long tuple unpacking in assignments.
@ -1123,7 +1135,7 @@ def normalize_invisible_parens(
if check_lpar:
if (
preview
mode.preview
and child.type == syms.atom
and node.type == syms.for_stmt
and isinstance(child.prev_sibling, Leaf)
@ -1136,7 +1148,9 @@ def normalize_invisible_parens(
remove_brackets_around_comma=True,
):
wrap_in_parentheses(node, child, visible=False)
elif preview and isinstance(child, Node) and node.type == syms.with_stmt:
elif (
mode.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(
@ -1147,17 +1161,7 @@ def normalize_invisible_parens(
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, ""))
_normalize_import_from(node, child, index)
break
elif (
index == 1
@ -1172,13 +1176,27 @@ def normalize_invisible_parens(
elif not (isinstance(child, Leaf) and is_multiline_string(child)):
wrap_in_parentheses(node, child, visible=False)
comma_check = child.type == token.COMMA if preview else False
comma_check = child.type == token.COMMA if mode.preview else False
check_lpar = isinstance(child, Leaf) and (
child.value in parens_after or comma_check
)
def _normalize_import_from(parent: Node, child: LN, index: int) -> None:
# "import from" nodes store parentheses directly as part of
# the statement
if is_lpar_token(child):
assert is_rpar_token(parent.children[-1])
# make parentheses invisible
child.value = ""
parent.children[-1].value = ""
elif child.type != token.STAR:
# insert invisible parentheses
parent.insert_child(index, Leaf(token.LPAR, ""))
parent.append_child(Leaf(token.RPAR, ""))
def remove_await_parens(node: Node) -> None:
if node.children[0].type == token.AWAIT and len(node.children) > 1:
if (
@ -1215,6 +1233,49 @@ def remove_await_parens(node: Node) -> None:
remove_await_parens(bracket_contents)
def _maybe_wrap_cms_in_parens(
node: Node, mode: Mode, features: Collection[Feature]
) -> None:
"""When enabled and safe, wrap the multiple context managers in invisible parens.
It is only safe when `features` contain Feature.PARENTHESIZED_CONTEXT_MANAGERS.
"""
if (
Feature.PARENTHESIZED_CONTEXT_MANAGERS not in features
or Preview.wrap_multiple_context_managers_in_parens not in mode
or len(node.children) <= 2
# If it's an atom, it's already wrapped in parens.
or node.children[1].type == syms.atom
):
return
colon_index: Optional[int] = None
for i in range(2, len(node.children)):
if node.children[i].type == token.COLON:
colon_index = i
break
if colon_index is not None:
lpar = Leaf(token.LPAR, "")
rpar = Leaf(token.RPAR, "")
context_managers = node.children[1:colon_index]
for child in context_managers:
child.remove()
# After wrapping, the with_stmt will look like this:
# with_stmt
# NAME 'with'
# atom
# LPAR ''
# testlist_gexp
# ... <-- context_managers
# /testlist_gexp
# RPAR ''
# /atom
# COLON ':'
new_child = Node(
syms.atom, [lpar, Node(syms.testlist_gexp, context_managers), rpar]
)
node.insert_child(1, new_child)
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

5
src/black/mode.py
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@ -50,6 +50,7 @@ class Feature(Enum):
EXCEPT_STAR = 14
VARIADIC_GENERICS = 15
DEBUG_F_STRINGS = 16
PARENTHESIZED_CONTEXT_MANAGERS = 17
FORCE_OPTIONAL_PARENTHESES = 50
# __future__ flags
@ -106,6 +107,7 @@ class Feature(Enum):
Feature.POS_ONLY_ARGUMENTS,
Feature.UNPACKING_ON_FLOW,
Feature.ANN_ASSIGN_EXTENDED_RHS,
Feature.PARENTHESIZED_CONTEXT_MANAGERS,
},
TargetVersion.PY310: {
Feature.F_STRINGS,
@ -120,6 +122,7 @@ class Feature(Enum):
Feature.POS_ONLY_ARGUMENTS,
Feature.UNPACKING_ON_FLOW,
Feature.ANN_ASSIGN_EXTENDED_RHS,
Feature.PARENTHESIZED_CONTEXT_MANAGERS,
Feature.PATTERN_MATCHING,
},
TargetVersion.PY311: {
@ -135,6 +138,7 @@ class Feature(Enum):
Feature.POS_ONLY_ARGUMENTS,
Feature.UNPACKING_ON_FLOW,
Feature.ANN_ASSIGN_EXTENDED_RHS,
Feature.PARENTHESIZED_CONTEXT_MANAGERS,
Feature.PATTERN_MATCHING,
Feature.EXCEPT_STAR,
Feature.VARIADIC_GENERICS,
@ -164,6 +168,7 @@ class Preview(Enum):
parenthesize_conditional_expressions = auto()
skip_magic_trailing_comma_in_subscript = auto()
wrap_long_dict_values_in_parens = auto()
wrap_multiple_context_managers_in_parens = auto()
class Deprecated(UserWarning):

35
tests/data/preview_context_managers/auto_detect/features_3_10.py Normal file
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@ -0,0 +1,35 @@
# This file uses pattern matching introduced in Python 3.10.
match http_code:
case 404:
print("Not found")
with \
make_context_manager1() as cm1, \
make_context_manager2() as cm2, \
make_context_manager3() as cm3, \
make_context_manager4() as cm4 \
:
pass
# output
# This file uses pattern matching introduced in Python 3.10.
match http_code:
case 404:
print("Not found")
with (
make_context_manager1() as cm1,
make_context_manager2() as cm2,
make_context_manager3() as cm3,
make_context_manager4() as cm4,
):
pass

37
tests/data/preview_context_managers/auto_detect/features_3_11.py Normal file
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@ -0,0 +1,37 @@
# This file uses except* clause in Python 3.11.
try:
some_call()
except* Error as e:
pass
with \
make_context_manager1() as cm1, \
make_context_manager2() as cm2, \
make_context_manager3() as cm3, \
make_context_manager4() as cm4 \
:
pass
# output
# This file uses except* clause in Python 3.11.
try:
some_call()
except* Error as e:
pass
with (
make_context_manager1() as cm1,
make_context_manager2() as cm2,
make_context_manager3() as cm3,
make_context_manager4() as cm4,
):
pass

30
tests/data/preview_context_managers/auto_detect/features_3_8.py Normal file
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@ -0,0 +1,30 @@
# This file doesn't use any Python 3.9+ only grammars.
# Make sure parens around a single context manager don't get autodetected as
# Python 3.9+.
with (a):
pass
with \
make_context_manager1() as cm1, \
make_context_manager2() as cm2, \
make_context_manager3() as cm3, \
make_context_manager4() as cm4 \
:
pass
# output
# This file doesn't use any Python 3.9+ only grammars.
# Make sure parens around a single context manager don't get autodetected as
# Python 3.9+.
with a:
pass
with make_context_manager1() as cm1, make_context_manager2() as cm2, make_context_manager3() as cm3, make_context_manager4() as cm4:
pass

34
tests/data/preview_context_managers/auto_detect/features_3_9.py Normal file
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@ -0,0 +1,34 @@
# This file uses parenthesized context managers introduced in Python 3.9.
with \
make_context_manager1() as cm1, \
make_context_manager2() as cm2, \
make_context_manager3() as cm3, \
make_context_manager4() as cm4 \
:
pass
with (
new_new_new1() as cm1,
new_new_new2()
):
pass
# output
# This file uses parenthesized context managers introduced in Python 3.9.
with (
make_context_manager1() as cm1,
make_context_manager2() as cm2,
make_context_manager3() as cm3,
make_context_manager4() as cm4,
):
pass
with new_new_new1() as cm1, new_new_new2():
pass

38
tests/data/preview_context_managers/targeting_py38.py Normal file
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@ -0,0 +1,38 @@
with \
make_context_manager1() as cm1, \
make_context_manager2() as cm2, \
make_context_manager3() as cm3, \
make_context_manager4() as cm4 \
:
pass
with \
make_context_manager1() as cm1, \
make_context_manager2(), \
make_context_manager3() as cm3, \
make_context_manager4() \
:
pass
with \
new_new_new1() as cm1, \
new_new_new2() \
:
pass
# output
with make_context_manager1() as cm1, make_context_manager2() as cm2, make_context_manager3() as cm3, make_context_manager4() as cm4:
pass
with make_context_manager1() as cm1, make_context_manager2(), make_context_manager3() as cm3, make_context_manager4():
pass
with new_new_new1() as cm1, new_new_new2():
pass

104
tests/data/preview_context_managers/targeting_py39.py Normal file
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@ -0,0 +1,104 @@
with \
make_context_manager1() as cm1, \
make_context_manager2() as cm2, \
make_context_manager3() as cm3, \
make_context_manager4() as cm4 \
:
pass
# Leading comment
with \
make_context_manager1() as cm1, \
make_context_manager2(), \
make_context_manager3() as cm3, \
make_context_manager4() \
:
pass
with \
new_new_new1() as cm1, \
new_new_new2() \
:
pass
with (
new_new_new1() as cm1,
new_new_new2()
):
pass
# Leading comment.
with (
# First comment.
new_new_new1() as cm1,
# Second comment.
new_new_new2()
# Last comment.
):
pass
with \
this_is_a_very_long_call(looong_arg1=looong_value1, looong_arg2=looong_value2) as cm1, \
this_is_a_very_long_call(looong_arg1=looong_value1, looong_arg2=looong_value2, looong_arg3=looong_value3, looong_arg4=looong_value4) as cm2 \
:
pass
# output
with (
make_context_manager1() as cm1,
make_context_manager2() as cm2,
make_context_manager3() as cm3,
make_context_manager4() as cm4,
):
pass
# Leading comment
with (
make_context_manager1() as cm1,
make_context_manager2(),
make_context_manager3() as cm3,
make_context_manager4(),
):
pass
with new_new_new1() as cm1, new_new_new2():
pass
with new_new_new1() as cm1, new_new_new2():
pass
# Leading comment.
with (
# First comment.
new_new_new1() as cm1,
# Second comment.
new_new_new2()
# Last comment.
):
pass
with (
this_is_a_very_long_call(
looong_arg1=looong_value1, looong_arg2=looong_value2
) as cm1,
this_is_a_very_long_call(
looong_arg1=looong_value1,
looong_arg2=looong_value2,
looong_arg3=looong_value3,
looong_arg4=looong_value4,
) as cm2,
):
pass

24
tests/test_format.py
View File

@ -1,3 +1,4 @@
import re
from dataclasses import replace
from typing import Any, Iterator
from unittest.mock import patch
@ -58,6 +59,29 @@ def test_preview_minimum_python_310_format(filename: str) -> None:
assert_format(source, expected, mode, minimum_version=(3, 10))
def test_preview_context_managers_targeting_py38() -> None:
source, expected = read_data("preview_context_managers", "targeting_py38.py")
mode = black.Mode(preview=True, target_versions={black.TargetVersion.PY38})
assert_format(source, expected, mode, minimum_version=(3, 8))
def test_preview_context_managers_targeting_py39() -> None:
source, expected = read_data("preview_context_managers", "targeting_py39.py")
mode = black.Mode(preview=True, target_versions={black.TargetVersion.PY39})
assert_format(source, expected, mode, minimum_version=(3, 9))
@pytest.mark.parametrize(
"filename", all_data_cases("preview_context_managers/auto_detect")
)
def test_preview_context_managers_auto_detect(filename: str) -> None:
match = re.match(r"features_3_(\d+)", filename)
assert match is not None, "Unexpected filename format: %s" % filename
source, expected = read_data("preview_context_managers/auto_detect", filename)
mode = black.Mode(preview=True)
assert_format(source, expected, mode, minimum_version=(3, int(match.group(1))))
# =============== #
# Complex cases
# ============= #