Expandable BBcode Parser

[AeroX]

Here is the expandable BBcode parser that I made.
You can add more bbcode tags just by calling a function within the class.

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<?php
class BBcode
{
   private $functions = Array();
   
   public function __construct()
   {
      self::addHook( "b", create_function( '$a,$v', 'return "<b>{$v}</b>";' ) );
      self::addHook( "i", create_function( '$a,$v', 'return "<i>{$v}</i>";' ) );
      self::addHook( "u", create_function( '$a,$v', 'return "<u>{$v}</u>";' ) );
      self::addHook( "strike", create_function( '$a,$v', 'return "<span style=\"text-decoration:line-through;\">{$v}</span>";' ) );
   }

   public function parse( $text )
   {
      $x = true;
      while( $x )
      {
         if( preg_match( "/\[([^=]*)(.*)\](.*)\[\/\\1\]/mU", $text ) )
         {
            $text = preg_replace( "/\[([^=]*)(.*)\](.*)\[\/\\1\]/emU", "self::run( \"$1\", \"$2\", \"$3\" )", $text );
         }
         else
         {
            return $text;
         }
      }
   }
   
   public function addHook( $bb, $function_name )
   {
      if( function_exists( $function_name ) )
      {
         $this->functions[ $bb ] = $function_name;
      }
      else
      {
         return FALSE;
      }
   }
   
   private function run( $bb, $attr, $value )
   {
      if( isset( $this->functions[ $bb ] ) )
      {
         $ret = call_user_func( $this->functions[ $bb ], $attr, $value );
         if( $ret != FALSE )
         {
            return $ret;
         }
         else
         {
            return "[{$bb}".(($attr!="")?$attr:"")."]{$value}[/{$bb}]";
         }
      }
      else
      {
         return "[{$bb}".(($attr!="")?$attr:"")."]{$value}[/{$bb}]";
      }
   }
}
?>

Example:

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<?php
$BBcode = new BBcode();
$BBcode->addHook( "big", create_function( '$a,$v', 'return "<span style=\"font-size:50px;\">{$v}</span>";' ) );
echo $BBcode->parse( "[big]My Big Text[/big]" );
?>

The way that you add new tags is by calling $BBcode->addHook( ), the first var is the name of the tag you want to hook, and the second is a string containing the name of the function you want to call. The function that you call needs to be able to take 2 variables. The first containing the attributes on the tag and the second containg the value between the opening and closing tags. e.g.

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[img=200x300]http://mysite/myimage.jpg[/img]

would call the function with the values

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...( "=200x300", "http://mysite/myimage.jpg" );

Another Example:

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$BBcode = new BBcode();

function BBcode_img( $attr, $value )
{
    if( preg_match( "/\A\=([0-9]*)\x([0-9]*)\Z/", $attr )
    {
        preg_replace( "/\A\=([0-9]*)\x([0-9]*)\Z/e", "$xy = Array( \"$1\", \"$2\" );", $attr );
        return "<img src=\"{$value}\" width=\"{$xy[0]}\" height=\"{$xy[1]}\" alt=\"\" />";
    }
    else
    {
        if( $value != "" )
        {
            return "<img src=\"{$value}\" alt=\"\" />";
        }
        else
        {
            return FALSE;
        }
    }
}
$BBcode->addHook( "img", "BBcode_img" );

$BBcode->parse( "[img=200x300]http://mysite/myimage.jpg[/img]" );