Bug #62646 [Com]: Impossible to escape/match delimiters within \Q \E
Edit report at https://bugs.php.net/bug.php?id=62646&edit=1
ID: 62646
Comment by: Andreas dot Klauer at metamorpher dot de
Reported by: Andreas dot Klauer at metamorpher dot de
Summary: Impossible to escape/match delimiters within \Q \E
Status: Not a bug
Type: Bug
Package: PCRE related
PHP Version: 5.3.15
Block user comment: N
Private report: N
New Comment:
But even if you escape the delimiter, it's not possible to match literal /#~ if one of those is
the delimiter; you have to escape it, but if you do escape it, it matches literal \/#~ instead of
just /#~.
Perl:
$subject = "foo/#~bar";
$subject =~ s/\Q\/#~\E/baz/;
print $subject;
=> "foobazbar"
PHP:
$subject = "foo/#~bar";
$subject = preg_replace("/\Q\/#~\E/", "baz", $subject);
echo $subject;
=> "foo/#~bar"
PHP tries to match literal \/#~ here.
Previous Comments:
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[2012-07-24 01:55:35] felipe@php.net
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to
report
a bug at http://bugs.php.net/how-to-report.php
Hi, the pcretest tool doesn't even handle the \Q..\E stuff as you mentioned. It works just like
the [..] one. And using Perl I did to escape the delimiter inside \Q..\E.
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[2012-07-24 00:33:54] Andreas dot Klauer at metamorpher dot de
Description:
------------
PCRE allows literal matches of strings between \Q and \E. This is also documented, \Q.$.\E will
match literal .$.
However, if that literal string contains the regexp delimiter (/ or # or ~ or () or whichever you
choose), the regexp compile either fails, or the match fails because it tries to match the escape
char used to escape the delimiter.
The problem is php_pcre::pcre_get_compiled_regex_cache() which parses the delimiter, not taking \Q
\E in account. Delimiters between \Q \E should be treated as literal characters, not delimiters
(that's what Perl does); or alternatively if delimiters have to be escaped, the escape char
should be removed from the pattern.
Workaround: Use preg_quote() instead of \Q \E if there's a chance the delimiter may appear
within \Q \E
Test script:
---------------
preg_replace("/\Q/#~\E/", ...);
=> Warning: preg_replace(): Unknown modifier '#' in php shell code on line 1
preg_replace("/\Q\/#~\E/", "OK", "/#~");
=> "/#~" (expected "OK")
preg_replace("/\Q\/#~\E/", "FAIL", "\/#~")
=> "FAIL" (expected "\/#~");
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Edit this bug report at https://bugs.php.net/bug.php?id=62646&edit=1
Thread (3 messages)