bbcode_2.php

<?php 

class Bbcode {
  const RES_STRING = 0;
  const RES_FUNC_OBJECT = 1;
  const RES_FUNC_NAME = 2;
  const POS_START_KEY = 'start';
  
  private static $patterns = array();
  private static $patterns_count=0;
  
  private $pattern;
  private $type;
  private $action;
  
  public static function replace($string) 
  {
    for($i=0; $i<self::$patterns_count; $i++) 
    {
      $string = self::$patterns[$i]->apply($string);
    }
    return $string;
  }
  
  public static function clear($string) 
  {
    for($i=0; $i<self::$patterns_count; $i++) 
    {
      $string = self::$patterns[$i]->filter($string);
    }
    return $string;
  }
  
  public function __construct($pattern, $action, $pos = 'end')
  {
    $this->pattern = $pattern;
    $this->action = $action;
    
    if(is_object($action))
    {
      $this->type = self::RES_FUNC_OBJECT;
    }
    elseif(is_string($action)) 
    {
      if(strstr($action, 'return'))
      {
        $this->action = create_function('$match',$this->action);

        $this->type = self::RES_FUNC_OBJECT;
      }
      elseif(substr ($action, -2 ) === '()')
      {
        $this->type = self::RES_FUNC_NAME;
      }
      else 
      {
        $this->type = self::RES_STRING;
      }
    }
    
    if($pos==self::POS_START_KEY)
    {
      array_unshift(self::$patterns, $this);
    }
    else
    {
      array_push(self::$patterns, $this);
    }
    
    self::$patterns_count += 1;
    
  }
  
  private function apply($string) 
  { 
    switch($this->type) 
    {
      case self::RES_STRING:
        $string = preg_replace($this->pattern, $this->action, $string);
        break;
      case self::RES_FUNC_OBJECT:
      case self::RES_FUNC_NAME:
        $string = preg_replace_callback($this->pattern, $this->action, $string);
    }
    
    return $string;
  }
  
  private function filter($string) 
  {
    return preg_replace($this->pattern, "$1", $string);
  }
  
}

new Bbcode("/\[b\](.*?)\[\/b\]/si","<strong>$1</strong>");
new Bbcode("/\[i\](.*?)\[\/i\]/si","<em>$1</em>");
new Bbcode("/\[u\](.*?)\[\/u\]/si","<span style=\"text-decoration: underline;\">$1</span>");

$string = '[b]Ich[/b] [i]heisse[/i] [u]Peter[/u]';

echo Bbcode::replace($string);
# <strong>Ich</strong> <em>heisse</em> <span style="text-decoration: underline;">Peter</span>

echo Bbcode::clear($string);
# Ich heisse Peter

?>