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Re^3: Unrecognized escape \Q passed through in regex

by ikegami (Pope)
on Jan 26, 2006 at 18:52 UTC ( #525815=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Unrecognized escape \Q passed through in regex
in thread Unrecognized escape \Q passed through in regex

Not necessarily. It won't work for

print($regexp) Expect Gives -------------- ------------ ---------- \Q*\E\Q*\E \*\* \*\Q*\E \Q**LOL** \*\*LOL\*\* \Q**LOL** \\Quit\\Exit \\Quit\\Exit \Quit\Exit \Qfoo\\E foo\\\\E foo\\

Solution:

my $in_quote = 0; $regexp =~ s/([^\\]|\\.)/ if ($in_quote) { if ($1 eq '\\E') { $in_quote = 0; '' } else { quotemeta($1) } } else { if ($1 eq '\\Q') { $in_quote = 1; '' } else { $1 } } /eg;

Update: Alternative:

$regexp =~ s/ \G ( (?:[^\\]|\\[^Q])* ) (?: \\Q (?:[^\\]|\\[^E])* (?:\\E)? )? / $1 . (defined($2) ? quotemeta($2) : '') /xge;

Neither snippet is fully tested. In fact, both are known to be unable to handle regexps in which (?{...}) or (?{{...}}) are used. What's wrong with what I suggested in my earlier post?


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Re^4: Unrecognized escape \Q passed through in regex
by Articuno (Beadle) on Jan 26, 2006 at 19:13 UTC
    But what's wrong with what I suggested in my earlier post?

    The regexes are in a DB. In the beginning, all of them where full regexes (no need for \Q...\E, etc...). But now, some of them are created by an user with a GUI. These "new" regexes are "plain text", and I want to ignore the metacharacters of *them* only, and not of all the regexes. If I "quotemeta" any regex i see, I can end up quoting real regexes :-(

    Oh, and the interface is not in Perl, so I don't have quotemeta there. All I can do is surround with \Q...\E and hope it works, but as I found out (the bad way), it doesn't :-(
    -- 6x9=42
      quotemeta should be easy to implement in any language. Adding a slash in front of any characters other than [a-zA-Z0-9] should do the trick.
        Ok... You won :-)
        (somehow i was thinking that there could be a problem with that... but now it's clear that it's safe ^_^;;; )
        -- 6x9=42

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