From 75f99bded33abe962ca08bf16c77635ac9ca00a1 Mon Sep 17 00:00:00 2001 From: Joe Young <80432516+jpy-git@users.noreply.github.com> Date: Sat, 9 Apr 2022 21:49:40 +0100 Subject: [PATCH] Remove redundant parentheses around awaited coroutines/tasks (#2991) This is a tricky one as await is technically an expression and therefore in certain situations requires brackets for operator precedence. However, the vast majority of await usage is just await some_coroutine(...) and similar in format to return statements. Therefore this PR removes redundant parens around these await expressions. Co-authored-by: Jelle Zijlstra Co-authored-by: Richard Si <63936253+ichard26@users.noreply.github.com> --- CHANGES.md | 1 + src/black/linegen.py | 41 +++++++- tests/data/remove_await_parens.py | 168 ++++++++++++++++++++++++++++++ tests/test_format.py | 1 + 4 files changed, 210 insertions(+), 1 deletion(-) create mode 100644 tests/data/remove_await_parens.py diff --git a/CHANGES.md b/CHANGES.md index c631aec..e168e24 100644 --- a/CHANGES.md +++ b/CHANGES.md @@ -14,6 +14,7 @@ +- Remove redundant parentheses around awaited objects (#2991) - Parentheses around return annotations are now managed (#2990) - Remove unnecessary parentheses from `with` statements (#2926) diff --git a/src/black/linegen.py b/src/black/linegen.py index c2b0616..caffbab 100644 --- a/src/black/linegen.py +++ b/src/black/linegen.py @@ -3,7 +3,7 @@ Generating lines of code. """ from functools import partial, wraps import sys -from typing import Collection, Iterator, List, Optional, Set, Union +from typing import Collection, Iterator, List, Optional, Set, Union, cast from black.nodes import WHITESPACE, RARROW, STATEMENT, STANDALONE_COMMENT from black.nodes import ASSIGNMENTS, OPENING_BRACKETS, CLOSING_BRACKETS @@ -253,6 +253,9 @@ class LineGenerator(Visitor[Line]): ): 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]: @@ -923,6 +926,42 @@ def normalize_invisible_parens( ) +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 diff --git a/tests/data/remove_await_parens.py b/tests/data/remove_await_parens.py new file mode 100644 index 0000000..eb7dad3 --- /dev/null +++ b/tests/data/remove_await_parens.py @@ -0,0 +1,168 @@ +import asyncio + +# Control example +async def main(): + await asyncio.sleep(1) + +# Remove brackets for short coroutine/task +async def main(): + await (asyncio.sleep(1)) + +async def main(): + await ( + asyncio.sleep(1) + ) + +async def main(): + await (asyncio.sleep(1) + ) + +# Check comments +async def main(): + await ( # Hello + asyncio.sleep(1) + ) + +async def main(): + await ( + asyncio.sleep(1) # Hello + ) + +async def main(): + await ( + asyncio.sleep(1) + ) # Hello + +# Long lines +async def main(): + await asyncio.gather(asyncio.sleep(1), asyncio.sleep(1), asyncio.sleep(1), asyncio.sleep(1), asyncio.sleep(1), asyncio.sleep(1), asyncio.sleep(1)) + +# Same as above but with magic trailing comma in function +async def main(): + await asyncio.gather(asyncio.sleep(1), asyncio.sleep(1), asyncio.sleep(1), asyncio.sleep(1), asyncio.sleep(1), asyncio.sleep(1), asyncio.sleep(1),) + +# Cr@zY Br@ck3Tz +async def main(): + await ( + ((((((((((((( + ((( ((( + ((( ((( + ((( ((( + ((( ((( + ((black(1))) + ))) ))) + ))) ))) + ))) ))) + ))) ))) + ))))))))))))) + ) + +# Keep brackets around non power operations and nested awaits +async def main(): + await (set_of_tasks | other_set) + +async def main(): + await (await asyncio.sleep(1)) + +# It's awaits all the way down... +async def main(): + await (await x) + +async def main(): + await (yield x) + +async def main(): + await (await (asyncio.sleep(1))) + +async def main(): + await (await (await (await (await (asyncio.sleep(1)))))) + +# output +import asyncio + +# Control example +async def main(): + await asyncio.sleep(1) + + +# Remove brackets for short coroutine/task +async def main(): + await asyncio.sleep(1) + + +async def main(): + await asyncio.sleep(1) + + +async def main(): + await asyncio.sleep(1) + + +# Check comments +async def main(): + await asyncio.sleep(1) # Hello + + +async def main(): + await asyncio.sleep(1) # Hello + + +async def main(): + await asyncio.sleep(1) # Hello + + +# Long lines +async def main(): + await asyncio.gather( + asyncio.sleep(1), + asyncio.sleep(1), + asyncio.sleep(1), + asyncio.sleep(1), + asyncio.sleep(1), + asyncio.sleep(1), + asyncio.sleep(1), + ) + + +# Same as above but with magic trailing comma in function +async def main(): + await asyncio.gather( + asyncio.sleep(1), + asyncio.sleep(1), + asyncio.sleep(1), + asyncio.sleep(1), + asyncio.sleep(1), + asyncio.sleep(1), + asyncio.sleep(1), + ) + + +# Cr@zY Br@ck3Tz +async def main(): + await black(1) + + +# Keep brackets around non power operations and nested awaits +async def main(): + await (set_of_tasks | other_set) + + +async def main(): + await (await asyncio.sleep(1)) + + +# It's awaits all the way down... +async def main(): + await (await x) + + +async def main(): + await (yield x) + + +async def main(): + await (await asyncio.sleep(1)) + + +async def main(): + await (await (await (await (await asyncio.sleep(1))))) diff --git a/tests/test_format.py b/tests/test_format.py index 6f71617..51d8fb0 100644 --- a/tests/test_format.py +++ b/tests/test_format.py @@ -83,6 +83,7 @@ PREVIEW_CASES: List[str] = [ "remove_except_parens", "remove_for_brackets", "one_element_subscript", + "remove_await_parens", "return_annotation_brackets", ] -- 2.39.5