From: Richard Si <63936253+ichard26@users.noreply.github.com> Date: Mon, 23 Aug 2021 02:52:19 +0000 (-0400) Subject: Improve f-string expression detection regex so ... (#2437) X-Git-Url: https://git.madduck.net/etc/vim.git/commitdiff_plain/8c04847aa22d14f01bb206cfc1b1e1cebd2ae538 Improve f-string expression detection regex so ... (#2437) we don't accidentally add backslashes to them when normalizing quotes because that's invalid syntax! The problem this commit fixes is that matches would eat too much blocking important matches to occur. For example, here's one f-string body: {a}{b}{c} I know there's no risk of introducing backslashes here, but the regex already goes sideways with this. Throwing this example at regex101 I get: {a}{b}{c} # The As and Bs are the two matches, and the upper ---- ---- # case letters are the groups with those matches. aAaa bbBb ... we've missed the middle expression (so if any backslashes in a more complex example were introduced there we wouldn't bail out even though we should -- hence the bug). As it stands the regex needs somesort of extra character (or the start/end of the body) around the expressions but that isn't always the case as shown above. The fix implemented here is to turn the "eat a surrounding non-curly bracket character" groups ie. `(?:[^{]|^)` and `(?:[^}]|$)` into negative lookaheads and lookbehinds. This still guarantees the already specified rules but without problematically eating extra characters ^^ --- diff --git a/CHANGES.md b/CHANGES.md index 3a96029..22ddc42 100644 --- a/CHANGES.md +++ b/CHANGES.md @@ -7,6 +7,8 @@ - Add support for formatting Jupyter Notebook files (#2357) - Move from `appdirs` dependency to `platformdirs` (#2375) - Present a more user-friendly error if .gitignore is invalid (#2414) +- The failsafe for accidentally added backslashes in f-string expressions has been + hardened to handle more edge cases during quote normalization (#2437) ### Integrations diff --git a/src/black/strings.py b/src/black/strings.py index 80f588f..d7b6c24 100644 --- a/src/black/strings.py +++ b/src/black/strings.py @@ -190,9 +190,9 @@ def normalize_string_quotes(s: str) -> str: if "f" in prefix.casefold(): matches = re.findall( r""" - (?:[^{]|^)\{ # start of the string or a non-{ followed by a single { + (?:(?