From: Andy Kluger <andykluger@gmail.com>
To: zsh-users@zsh.org
Subject: Help: f (repeat) modifier, and histsubstpattern + :s/l/r/ modifier escaping of [{()}]
Date: Wed, 16 Aug 2023 14:32:51 -0400 [thread overview]
Message-ID: <CAO4D9E=+O-=66w0um7OzENVEiV11QfVUWYSTocacUX4rhYr1=Q@mail.gmail.com> (raw)
Hello!
For a small exercise I wanted to repeatedly remove empty pairs of
brackets/braces/parentheses from a string, and started with this
working solution:
s=$1 l=$#s
while (( 1 )) {
s=${s//(\{\}|\(\)|\[\])}
if [[ $#s < $l ]] { l=$#s } else { break }
}
print -r -- $s
But I remembered reading about the f (repeat) modifier, and thought
I'd try to remove the while loop.
setopt histsubstpattern
s='left[()]over'
print -rl -- ${s:fs/(\\{\\}|\\(\\)|\\[\\])//}
# printed: left[]over
# expected: leftover
I'm having two confusions:
1. Why do I need to double-backslash before each
brace/bracket/parenthesis, rather than single-backslash?
2. Why doesn't the replacement seem to happen to each subsequent
result of a former replacement?
Thanks for any help!
Andy
next reply other threads:[~2023-08-16 18:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-16 18:32 Andy Kluger [this message]
2023-08-17 3:19 ` Bart Schaefer
2023-08-17 23:09 ` Bart Schaefer
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