Question

Once again I’m stuck at regular expression. There is nowhere any good material where to learn the more advance usage.

I’m trying to match [image width="740" height="249" parameters=""]51lca7dn56.jpg[/image] to $cache->image_tag("$4", $1, $2, "$3").

Everything works great if all the [image] parameters are there, but I need it to match, even if something is missing. So for example [image width="740"]51lca7dn56.jpg[/image].

Current code is:

$text = preg_replace('#\[image width=\"(.*?)\" height=\"(.*?)\" parameters=\"(.*?)\"\](.*?)\[/image\]#e', '$cache->image_tag("$4", $1, $2, "$3")', $text);

Regular expression is the only thing that always gets me stuck, so if anybody could also refer some good resource, so I could manage these types of issues myself, it would be much appreciated.

My dummy version what I’m trying to do is this:

// match only [image]
$text = preg_replace('#\[image\](.*?)\[/image\]#si', '$cache->image_tag("$1", 0, 0, "")', $text);
// match only width
$text = preg_replace('#\[image width=\"(.*?)\"\](.*?)\[/image\]#si', '$cache->image_tag("$2", $1, 0, "")', $text);
// match only width and height
$text = preg_replace('#\[image width=\"(.*?)\" height=\"(.*?)\"\](.*?)\[/image\]#si', '$cache->image_tag("$3", $1, $2, "")', $text);
// match only all
$text = preg_replace('#\[image width=\"(.*?)\" height=\"(.*?)\" parameters=\"(.*?)\"\](.*?)\[/image\]#si', '$cache->image_tag("$4", $1, $2, $3)', $text);

(This code actually doesn’t work as expected, but you will understand my point more better.) I hope to put all this horrible mess into one RE call basically.

Final code tested and working based on Ωmega’s answer:

// Match: [image width="740" height="249" parameters="bw"]51lca7dn56.jpg[/image]
$text = preg_replace('#\[image\b(?=(?:[^\]]*\bwidth="(\d+)"|))(?=(?:[^\]]*\bheight="(\d+)"|))(?=(?:[^\]]*\bparameters="([^"]+)"|))[^\]]*\]([^\[]*)\[\/image\]#si', '$cache->image_tag("$4", $1, $2, "$3")', $text); // the end is #si, so it would be eaiser to debug, in reality its #e

However, since if width or height might not be there, it will return empty not NULL. So I adopted drews idea of preg_replace_callback():

$text = preg_replace_callback('#\[image\b(?=(?:[^\]]*\bwidth="(\d+)"|))(?=(?:[^\]]*\bheight="(\d+)"|))(?=(?:[^\]]*\bparameters="([^"]+)"|))[^\]]*\]([^\[]*)\[\/image\]#', create_function(
'$matches',
'global $cache; return $cache->image_tag($matches[4], ($matches[1] ? $matches[1] : 0), ($matches[2] ? $matches[2] : 0), $matches[3]);'), $text);

Answer 1

I would suggest you to use regex

\[image\b(?=(?:[^\]]*\bwidth="(\d+)"|))(?=(?:[^\]]*\bheight="(\d+)"|))(?=(?:[^\]]*\bparameters="([^"]+)"|))[^\]]*\]([^\[]*)\[\/image\]

---

Edit:

$string = 'this is some code and it has bbcode in it like [image width="740" height="249" parameters=""]51lca7dn56.jpg[/image] for example and [image parameters="" height="123" width="456"]12345.jpg[/image].';

if (preg_match_all('/\[image\b(?=(?:[^\]]*\bwidth="(\d+)"|))(?=(?:[^\]]*\bheight="(\d+)"|))(?=(?:[^\]]*\bparameters="([^"]+)"|))[^\]]*\]([^\[]*)\[\/image\]/i', $string, $match) > 0) {
    var_dump($match);
}

Output:

array(5) {
  [0]=>
  array(2) {
    [0]=>
    string(68) "[image width="740" height="249" parameters=""]51lca7dn56.jpg[/image]"
    [1]=>
    string(63) "[image parameters="" height="123" width="456"]12345.jpg[/image]"
  }
  [1]=>
  array(2) {
    [0]=>
    string(3) "740"
    [1]=>
    string(3) "456"
  }
  [2]=>
  array(2) {
    [0]=>
    string(3) "249"
    [1]=>
    string(3) "123"
  }
  [3]=>
  array(2) {
    [0]=>
    string(0) ""
    [1]=>
    string(0) ""
  }
  [4]=>
  array(2) {
    [0]=>
    string(14) "51lca7dn56.jpg"
    [1]=>
    string(9) "12345.jpg"
  }
}