Функция обработки bb-кодов

// Функция обработки bbCode
function print_page($message)
{
  // Разрезаем слишком длинные слова
    $message = preg_replace_callback(
              "|([a-zа-я\d!]{35,})|i",
              "split_text",
              $message);
        
  // Тэги - [code], [php]
  preg_match_all( "#\[php\](.+)\[\/php\]#isU", $message, $matches );
  $cnt = count( $matches[0] );
  for ( $i = 0; $i < $cnt; $i++ ) {
    $phpBlocks[] = '<div class="codePHP">'.highlight_string( $matches[1][$i], true ).'</div>';
    $uniqidPHP = '[php_'.uniqid('').']';
    $uniqidsPHP[] = $uniqidPHP;
    $message = str_replace( $matches[0][$i], $uniqidPHP, $message ); 
  }

  $spaces = array( ' ', "\t" );
  $entities = array( ' ', '    ' );
  
  preg_match_all( "#\[code\](.+)\[\/code\]#isU", $message, $matches );
  $cnt = count( $matches[0] );

  for ( $i = 0; $i < $cnt; $i++ ) {
    $codeBlocks[] = '<div class="code">'.nl2br( str_replace( $spaces, $entities, htmlspecialchars( $matches[1][$i] ) ) ).'</div>';
    $uniqidCode = '[code_'.uniqid('').']';
    $uniqidsCode[] = $uniqidCode;
    $message = str_replace( $matches[0][$i], $uniqidCode, $message ); 
  }
  
  $message = htmlspecialchars( $message );
  $message = preg_replace("#\[b\](.+)\[\/b\]#isU", '<b>\\1</b>', $message);
  $message = preg_replace("#\[i\](.+)\[\/i\]#isU", '<i>\\1</i>', $message);
  $message = preg_replace("#\[u\](.+)\[\/u\]#isU", '<u>\\1</u>', $message);
  $message = preg_replace("#\[quote\](.+)\[\/quote\]#isU",'<div class="quoteHead">Цитата</div><div class="quoteContent">\\1</div>',$message);
  $message = preg_replace("#\[quote="([- 0-9a-zа-яА-Я]{1,30})"\](.+)\[\/quote\]#isU", '<div class="quoteHead">\\1 пишет:</div><div class="quoteContent">\\2</div>', $message);
  $message = preg_replace("#\[url\][\s]*([\S]+)[\s]*\[\/url\]#isU",'<a href="\\1" target="_blank">\\1</a>',$message);
  $message = preg_replace("#\[url[\s]*=[\s]*([\S]+)[\s]*\][\s]*([^\[]*)\[/url\]#isU",
                             '<a href="\\1" target="_blank">\\2</a>',
                             $message);
  $message = preg_replace("#\[img\][\s]*([\S]+)[\s]*\[\/img\]#isU",'<img src="\\1" alt="" />',$message);
  $message = preg_replace("#\[color=red\](.+)\[\/color\]#isU",'<span style="color:#FF0000">\\1</span>',$message);
  $message = preg_replace("#\[color=green\](.+)\[\/color\]#isU",'<span style="color:#008000">\\1</span>',$message);
  $message = preg_replace("#\[color=blue\](.+)\[\/color\]#isU",'<span style="color:#0000FF">\\1</span>',$message);
  $message = preg_replace_callback("#\[list\]\s*((?:\[\*\].+)+)\[\/list\]#siU",'getUnorderedList',$message);
  $message = preg_replace_callback("#\[list=([a|1])\]\s*((?:\[\*\].+)+)\[\/list\]#siU", 'getOrderedList',$message);
  
  $message = nl2br( $message);
  
  if ( isset( $uniqidCode ) ) $message = str_replace( $uniqidsCode, $codeBlocks, $message );
  if ( isset( $uniqidPHP ) ) $message = str_replace( $uniqidsPHP, $phpBlocks, $message );
  
  return $message;
}

Более компактный вариант добавления BB-кодов

function AddBB($var) {
        $search = array(
                '/\[b\](.*?)\[\/b\]/is',
                '/\[i\](.*?)\[\/i\]/is',
                '/\[u\](.*?)\[\/u\]/is',
                '/\[img\](.*?)\[\/img\]/is',
                '/\[url\](.*?)\[\/url\]/is',
                '/\[url\=(.*?)\](.*?)\[\/url\]/is'
                );

        $replace = array(
                '<strong>$1</strong>',
                '<em>$1</em>',
                '<u>$1</u>',
                '<img src="$1" />',
                '<a href="$1">$1</a>',
                '<a href="$1">$2</a>'
                );

        $var = preg_replace ($search, $replace, $var);
        return $var;
}