4 ms·

sed seriously needs a Perl-regex mode... it's stuck in the Basic/Extended Regex syntaxes, which feel prehistoric and don't support the syntax that you will lear

by j1elo 6y ago

sed seriously needs a Perl-regex mode... it's stuck in the Basic/Extended Regex syntaxes, which feel prehistoric and don't support the syntax that you will learn in practically any modern regex tutorial. Maybe they could take the opportunity to add that. Otherwise I end up needing to sed -i 's/sed -i/perl -pi -e/g' *

eru 6y ago
Keep in mind that Perl regexen can not be recognized in linear time.
- jjice 6y ago
  While true, you can get similar syntax without backtracking in linear time, which is what the Rust regex crate and ripgrep use.
  - eru 6y ago
    Yes. You can take a subset of Perl's syntax.
tyingq 6y ago
It looks like they did consider it: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=22801 https://debbugs.gnu.org/cgi/bugreport.cgi?bug=22801
bewuethr 6y ago
Sed isn't part of the coreutils, though, so this would be outside of the scope of at least this project. There is https://github.com/chmln/sd https://github.com/chmln/sd written in Rust, but it's far from a sed replacement – it's reducing it to search and replace for fixed strings, as far as I can tell.
chubot 6y ago
FWIW this is one reason I designed the Eggex sublanguage of Oil to translate to extended regexps: so you can use it with egrep, awk, and sed --regexp-extended. https://www.oilshell.org/release/latest/doc/eggex.html https://www.oilshell.org/release/latest/doc/eggex.html It really annoys me to have to remember multiple syntaxes for regexes in shell scripts! Also, even if you added Perl syntax to sed today, it wouldn't be available everywhere. Oil isn't available everywhere either but there are some advantages to having the syntax in the shell rather than in every tool. (It's also easy to translate eggex to the BRE syntax or Perl syntax, but nobody has done so yet)
- j1elo 6y ago
  Albeit the typical first reaction might be that of XKCD 927 (I must confess it was mine, at least), I believe that the regular expressions area is territory that could see some innovation. If told to pick just one feature from eggex, I'd choose the ability to parse statically! FWIW I think this deserves a submission of its own, so here it is: https://news.ycombinator.com/item?id=26408510 https://news.ycombinator.com/item?id=26408510

by j1elo 6y ago

eru 6y ago

Keep in mind that Perl regexen can not be recognized in linear time.

jjice 6y ago
While true, you can get similar syntax without backtracking in linear time, which is what the Rust regex crate and ripgrep use.
- eru 6y ago
  Yes. You can take a subset of Perl's syntax.

tyingq 6y ago

It looks like they did consider it: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=22801 https://debbugs.gnu.org/cgi/bugreport.cgi?bug=22801

bewuethr 6y ago

Sed isn't part of the coreutils, though, so this would be outside of the scope of at least this project. There is https://github.com/chmln/sd https://github.com/chmln/sd written in Rust, but it's far from a sed replacement – it's reducing it to search and replace for fixed strings, as far as I can tell.

chubot 6y ago

FWIW this is one reason I designed the Eggex sublanguage of Oil to translate to extended regexps: so you can use it with egrep, awk, and sed --regexp-extended. https://www.oilshell.org/release/latest/doc/eggex.html https://www.oilshell.org/release/latest/doc/eggex.html It really annoys me to have to remember multiple syntaxes for regexes in shell scripts! Also, even if you added Perl syntax to sed today, it wouldn't be available everywhere. Oil isn't available everywhere either but there are some advantages to having the syntax in the shell rather than in every tool. (It's also easy to translate eggex to the BRE syntax or Perl syntax, but nobody has done so yet)

j1elo 6y ago
Albeit the typical first reaction might be that of XKCD 927 (I must confess it was mine, at least), I believe that the regular expressions area is territory that could see some innovation. If told to pick just one feature from eggex, I'd choose the ability to parse statically! FWIW I think this deserves a submission of its own, so here it is: https://news.ycombinator.com/item?id=26408510 https://news.ycombinator.com/item?id=26408510