How to Mimic Stack Overflow\'s Auto-Link Functionality in PHP?

Mimicking Stack Overflow's Auto-Link Functionality

To enhance web content, consider simulating Stack Overflow's automatic linking feature. This function enables the conversion of plain URLs into visually appealing hyperlinks.

Implementation in PHP

Here's a PHP function inspired by Stack Overflow's behavior:

<code class="php">function auto_link_text($text)
{
   // URL matching regex pattern from Daring Fireball
   $pattern  = '(?i)\b((?:[a-z][\w-]+:(?:/{1,3}|[a-z0-9%])|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:\'".,<>?«»“”‘’]))';

   $callback = create_function('$matches', '
       $url       = array_shift($matches);
       $url_parts = parse_url($url);

       $text = parse_url($url, PHP_URL_HOST) . parse_url($url, PHP_URL_PATH);
       $text = preg_replace("/^www./", "", $text);

       $last = -(strlen(strrchr($text, "/"))) + 1;
       if ($last < 0) {
           $text = substr($text, 0, $last) . "&amp;hellip;";
       }

       return sprintf(\'<a rel="nofollow" href="%s">%s</a>\', $url, $text);
   ');

   return preg_replace_callback($pattern, $callback, $text);
}</code>

Example Usage

Consider the following input text:

<code class="text">This is my text.  I wonder if you know about asking questions on StackOverflow:
 Check This out http://www.stackoverflow.com/questions/1925455/how-to-mimic-stackoverflow-auto-link-behavior

 Also, base_convert php function?
http://pt.php.net/manual/en/function.base-convert.php#52450

http://pt.php.net/manual/en/function.base-convert.php?wtf=hehe#52450</code>

Using the auto_link_text function, this text is transformed:

<code class="html">This is my text.  I wonder if you know about asking questions on StackOverflow:
 Check This out <a rel="nofollow" href="http://www.stackoverflow.com/questions/1925455/how-to-mimic-stackoverflow-auto-link-behavior">stackoverflow.com/questions/1925455/&hellip;</a>

 Also, base_convert php function?
<a rel="nofollow" href="http://pt.php.net/manual/en/function.base-convert.php#52450">pt.php.net/manual/en/&hellip;</a>

<a rel="nofollow" href="http://pt.php.net/manual/en/function.base-convert.php?wtf=hehe#52450">pt.php.net/manual/en/&hellip;</a></code>

Customization

You can tailor the linking behavior by modifying the callback function. For instance, you could:

• Alter the link text format
• Add additional attributes to the link tag
• Exclude certain URLs from auto-linking

By tweaking the implementation, you can create a custom auto-linking solution that meets your specific needs.

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