Re: efficient char escape sequence substitution

This is safer than an overall string-eval, and seems to work as desired, replacing only backslash-escapes:

use strict;
use warnings;

s/(\\(?:\W|\w{1,3}))/qq("$1")/gee, print for <DATA>;
__DATA__
this is a string\t$foowith some text\r\n
this is a string\010with some\x09text\r\n
[download]

Caution: Contents may have been coded under pressure.

Comment on Re: efficient char escape sequence substitution Download Code

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Re^2: efficient char escape sequence substitution by nobull (Friar) on May 28, 2005 at 07:51 UTC
That doesn't handle wide-character escapes. In comp.lang.perl.misc I recently offered this solution. `s/(\\[^"\$\@]+)/qq("$1")/eeg;` [download] Note that's not 100% infalible but AFAIK it's not a security problem and copes with all reasonable strings. It does have the interesting side effect of stripping \$ \" and \@ - but those have no buisness being in most of the sort of strings you'll encounter.	[reply] [d/l]
Re^3: efficient char escape sequence substitution by Roy Johnson (Monsignor) on May 28, 2005 at 21:42 UTC
How wide is a wide character escape? There's no reason that you can't change the quantifier in my regex to accommodate them. I just wasn't aware of any escapes wider than three characters. Caution: Contents may have been coded under pressure.	[reply]
Re^4: efficient char escape sequence substitution by nobull (Friar) on May 28, 2005 at 22:18 UTC
I don't think there's a fixed maximum \N{WHITE SMILING FACE}.	[reply]
Re^2: efficient char escape sequence substitution by mifflin (Curate) on May 27, 2005 at 23:08 UTC
Can you help me understand your regex modifiers? gee Where in perldoc can I find an explanation?	[reply]
Re^3: efficient char escape sequence substitution by Roy Johnson (Monsignor) on May 27, 2005 at 23:35 UTC
Documentation. `g` means global replace. `e` means eval the substitution space before substituting it. Repeating the `e` means eval it again. So it starts out looking like the string `qr("\\t")`; after an eval, it looks like `"\t"`, and after a 2nd eval, it's just a tab. (Actually, it may have captured more than just the tab, but anything after the tab is left intact.) Caution: Contents may have been coded under pressure.	[reply] [d/l] [select]