Two questions regarding regular expressions - php

Question

I currently use this:
$text = preg_replace('/' . $line . '/', '[x]\\0[/x]', $text);
$line is a simple regular expression:
https?://(?:.+?\.)?dailymotion\.com/video/[A-Za-z0-9]+
This is working fine so far. But there are two things that I need and I can't figure out, how to do that:
... I don't want to perform the replacement, if that string is contained within a BBCode i.e.
[bla]http://www.dailymotion.com/video/xuams9[/bla]
or
[bla=http://www.dailymotion.com/video/xuams9]trololo[/bla]
or
[bla='http://www.dailymotion.com/video/xuams9']http://www.dailymotion.com/video/xuams9[/bla]
The 2nd thing is, that I just want to match until the first space. This is what I currently use:
$text = preg_replace('/' . $line . '(?:[^ ]+)?/', '[x]\\0[/x]', $text);
I don't know, if I should do it like this or if there's a better way.
So, basically i'm just trying to match
http://www.dailymotion.com/video/test4
from this:
[tagx='http://www.dailymotion.com/video/test1']http://www.dailymotion.com/video/test2[/tagx] | [tagy]Hello http://www.dailymotion.com/video/test3 World[/tagy] | [tagz]Hello World[/tagz] http://www.dailymotion.com/video/test4
EDIT:
This is, what i have so far (which works slightly):
(?:(?<!(\[\/url\]|\[\/url=))(\s|^))' . $line . '(?:[^ ]+)(?:(?<![[:punct:]])(\s|\.?$))?

Answer 1

You can use a lookbehind assertions to do this.
http://php.net/manual/en/regexp.reference.assertions.php
By using the following lookbehind before $line
(?<!\[bla]|\[bla=|\[bla=')
it will match $link that is not starting with [bla], [bla= and [bla='.

Answer 2

→ Try this:
$text = array();
$text[ 0 ] = "[bla]http://www.dailymotion.com/video/xuams9[/bla]";
$text[ 1 ] = "[bla=http://www.dailymotion.com/video/xuams9]trololo[/bla]";
$text[ 2 ] = "http://www.dailymotion.com/video/xuams9";
$text[ 3 ] = "A http://www.dailymotion.com/video/xuams9 B C";
$line = "/http:\/\/www.dailymotion\.com\/video\/[A-Za-z0-9]+/";
$tag = array();
$tag[ 0 ] = "/\[[A-Za-z]{1,12}\]http:\/\/www.dailymotion\.com\/video\/[A-Za-z0-9]+\[\/[A-Za-z]{1,12}\]/";
$tag[ 1 ] = "/\[[A-Za-z]{1,12}=http:\/\/www.dailymotion\.com\/video\/[A-Za-z0-9]+\][A-Za-z0-9]{0,}\[\/[A-Za-z]{1,12}\]/";
foreach( $text as $k=>$v ) {
if( preg_match( $tag[ 0 ], $v ) == false && preg_match( $tag[ 1 ], $v ) == false ) {
echo '!';
$output = preg_replace( $line, '[x]\\0[/x]', $v );
}
else { $output = $v; };
echo "Text #" . ( $k + 1 ) . ": {$output}<br />";
}
Result:
Text #1: [bla]http://www.dailymotion.com/video/xuams9[/bla]
Text #2: [bla=http://www.dailymotion.com/video/xuams9]trololo[/bla]
!Text #3: [x]http://www.dailymotion.com/video/xuams9[/x]
!Text #4: A [x]http://www.dailymotion.com/video/xuams9[/x] B C