Edit report at https://bugs.php.net/bug.php?id=61780&edit=1
ID: 61780
User updated by: danielklein at airpost dot net
Reported by: danielklein at airpost dot net
Summary: Inconsistent PCRE captures in match results
Status: No Feedback
Type: Bug
Package: PCRE related
PHP Version: 5.4.0
Block user comment: N
Private report: N
New Comment:
@michael: Your code has a bug in it. There is an extra slash "/" in your pattern. The code
works as expected if you remove it.
@pajoye: This bug is still happening. It could be a bug in PCRE itself but I don't know how PHP
gets its results from it.
By the way, I can't set this bug back to Re-Opened. It says: "ERROR:
You aren't allowed to change a bug to that state."
Previous Comments:
------------------------------------------------------------------------
[2013-10-15 11:54:33] php-bugs at lists dot php dot net
No feedback was provided. The bug is being suspended because
we assume that you are no longer experiencing the problem.
If this is not the case and you are able to provide the
information that was requested earlier, please do so and
change the status of the bug back to "Re-Opened". Thank you.
------------------------------------------------------------------------
[2013-02-11 09:00:19] pajoye@php.net
Be sure that every testing environment uses the exact same version of PCRE. PHP
only uses it and does not affect by any mean the parsing.
------------------------------------------------------------------------
[2013-02-11 08:56:33] michael at mbaas dot de
Here is a reproduceable example (PHP 5.3.20 and 5.3.21) where named captures do
not return matches at all! I've tested this pattern against the PCRE-
Implementation in another language and it worked...
<?php
$QQ=chr(92) . chr(34);
$delimeters = "{}";
$del0 = preg_quote($delimeters{0});
$del1 = preg_quote($delimeters{1});
$tag="language";
$string="fdfdfdfdf{language=1}testhgg";
$preg = "~" . $del0 . $tag . "\s*=\s*(?P<" . "quote>[" . $QQ .
"\']*)(?
P<att>.*?)(?P=quote)\s*/" . $del1 . "~";
$match=array();
preg_match($preg,$string,$match);
echo "<br>string = " . htmlspecialchars($string) . "<br>preg=" .
htmlspecialchars($preg) .
"<br>match:<pre>";var_dump($match);echo"</pre>";
?>
------------------------------------------------------------------------
[2012-04-20 00:54:39] danielklein at airpost dot net
Description:
------------
Named and unnamed captures in both preg_match and preg_match_all (and probably preg_replace and the
other PCRE functions too but I haven't tested them all) can capture the wrong number of
parentheses if alternation or a zero-or-more quantifier is used.
If the pattern '/(?<b>b)|(?<c>c)|(?<d>d)/' is used to match
'c', both 'b' and 'c' will be set in the results array but
'd' won't be. 'b' should not be set (even to an empty string) as it failed
to match anything. However, if it was trying to match '/(?<b>b?)(?<c>c)/'
(note: optional 'b' AND mandatory 'c'), 'b' _should_ be set to
'' as it's allowed to match a zero-length string. If a match gets tried but it fails
and a capture later in the pattern works, the skipped capture should never produce a key in the
results array. It should be OK to leave holes in the numbered sequence (e.g. match 0 and 2 but not
1).
Currently, you need to use PREG_OFFSET_CAPTURE and test to see if the key exists, and if it does,
test to see if the capture position is -1. If this bug is fixed, capture positions will never be -1
as the key won't exist. Alternatively, an additional flag could be added (e.g.
PREG_KEEP_NONMATCHES) to create keys for ALL captures whether used or not (so, in the first pattern
above, keys would be created for 'b', 'c' and 'd' in all cases, and if
matching the string 'c' the offsets for both 'b' and 'd' would be -1).
In summary, if the pattern '/(?<b>b)|(?<c>c)|(?<d>d)/' is used to match
'c', by default it should only ever create a key for 'c'. If desired, an
additional flag could be added so that it creates keys for all captures: 'b',
'c' and 'd'. The current behaviour where it creates a key for 'b' and
'c' but not 'd' should be considered a bug and fixed.
Test script:
---------------
print('<pre>');
$offset = 0;
while (preg_match('/(?:(?<b>b)|(?<c>c)|(?<d>d))(?<e>e)?/',
'cdec', $matches, PREG_OFFSET_CAPTURE, $offset)) {
$offset = $matches[0][1] + strlen($matches[0][0]);
var_export($matches);
print("\n\n");
}
print("****************\n\n");
preg_match_all('/(?:(?<b>b)|(?<c>c)|(?<d>d))(?<e>e)?/',
'cdec', $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER);
var_export($matches);
print('</pre>');
Expected result:
----------------
array (
0 =>
array (
0 => 'c',
1 => 0,
),
'c' =>
array (
0 => 'c',
1 => 0,
),
2 =>
array (
0 => 'c',
1 => 0,
),
)
array (
0 =>
array (
0 => 'de',
1 => 1,
),
'd' =>
array (
0 => 'd',
1 => 1,
),
3 =>
array (
0 => 'd',
1 => 1,
),
'e' =>
array (
0 => 'e',
1 => 2,
),
4 =>
array (
0 => 'e',
1 => 2,
),
)
array (
0 =>
array (
0 => 'c',
1 => 3,
),
'c' =>
array (
0 => 'c',
1 => 3,
),
2 =>
array (
0 => 'c',
1 => 3,
),
)
****************
array (
0 =>
array (
0 =>
array (
0 => 'c',
1 => 0,
),
'c' =>
array (
0 => 'c',
1 => 0,
),
2 =>
array (
0 => 'c',
1 => 0,
),
),
1 =>
array (
0 =>
array (
0 => 'de',
1 => 1,
),
'd' =>
array (
0 => 'd',
1 => 1,
),
3 =>
array (
0 => 'd',
1 => 1,
),
'e' =>
array (
0 => 'e',
1 => 2,
),
4 =>
array (
0 => 'e',
1 => 2,
),
),
2 =>
array (
0 =>
array (
0 => 'c',
1 => 3,
),
'c' =>
array (
0 => 'c',
1 => 3,
),
2 =>
array (
0 => 'c',
1 => 3,
),
),
)
Actual result:
--------------
array (
0 =>
array (
0 => 'c',
1 => 0,
),
'b' =>
array (
0 => '',
1 => -1,
),
1 =>
array (
0 => '',
1 => -1,
),
'c' =>
array (
0 => 'c',
1 => 0,
),
2 =>
array (
0 => 'c',
1 => 0,
),
)
array (
0 =>
array (
0 => 'de',
1 => 1,
),
'b' =>
array (
0 => '',
1 => -1,
),
1 =>
array (
0 => '',
1 => -1,
),
'c' =>
array (
0 => '',
1 => -1,
),
2 =>
array (
0 => '',
1 => -1,
),
'd' =>
array (
0 => 'd',
1 => 1,
),
3 =>
array (
0 => 'd',
1 => 1,
),
'e' =>
array (
0 => 'e',
1 => 2,
),
4 =>
array (
0 => 'e',
1 => 2,
),
)
array (
0 =>
array (
0 => 'c',
1 => 3,
),
'b' =>
array (
0 => '',
1 => -1,
),
1 =>
array (
0 => '',
1 => -1,
),
'c' =>
array (
0 => 'c',
1 => 3,
),
2 =>
array (
0 => 'c',
1 => 3,
),
)
****************
array (
0 =>
array (
0 =>
array (
0 => 'c',
1 => 0,
),
'b' =>
array (
0 => '',
1 => -1,
),
1 =>
array (
0 => '',
1 => -1,
),
'c' =>
array (
0 => 'c',
1 => 0,
),
2 =>
array (
0 => 'c',
1 => 0,
),
),
1 =>
array (
0 =>
array (
0 => 'de',
1 => 1,
),
'b' =>
array (
0 => '',
1 => -1,
),
1 =>
array (
0 => '',
1 => -1,
),
'c' =>
array (
0 => '',
1 => -1,
),
2 =>
array (
0 => '',
1 => -1,
),
'd' =>
array (
0 => 'd',
1 => 1,
),
3 =>
array (
0 => 'd',
1 => 1,
),
'e' =>
array (
0 => 'e',
1 => 2,
),
4 =>
array (
0 => 'e',
1 => 2,
),
),
2 =>
array (
0 =>
array (
0 => 'c',
1 => 3,
),
'b' =>
array (
0 => '',
1 => -1,
),
1 =>
array (
0 => '',
1 => -1,
),
'c' =>
array (
0 => 'c',
1 => 3,
),
2 =>
array (
0 => 'c',
1 => 3,
),
),
)
------------------------------------------------------------------------
--
Edit this bug report at https://bugs.php.net/bug.php?id=61780&edit=1