<?php
function Parse_Tag_EGIK_Recursive($Input){
	$tmp = $Input;
    $tmp2 = preg_replace('#\[EGIK\](.*)\[/EGIK]#', '<em>$1</em>', $Input);
    if($tmp <> $tmp2)
    	return Parse_Tag_EGIK_Recursive($tmp2);
    return $tmp2;
}

function Parse_Tag_KALIN_Recursive($Input){
	$tmp = $Input;
    $tmp2 = preg_replace('#\[KALIN\](.*)\[/KALIN]#', '<b>$1</b>', $Input);
    if($tmp <> $tmp2)
    	return Parse_Tag_KALIN_Recursive($tmp2);
    return $tmp2;
}

function Parse_Tag_BUYUK_Recursive($Input){
	$tmp = $Input;
    $tmp2 = preg_replace('#\[BUYUK\](.*)\[/BUYUK]#', '<span style="font-size:24px">$1</span>', $Input);
    if($tmp <> $tmp2)
    	return Parse_Tag_BUYUK_Recursive($tmp2);
    return $tmp2;
}

$Content = <<<_EOF

[EGIK]testtest[KALIN]test2test2[/KALIN]test3test3[/EGIK]
<br>
[KALIN]lorem [BUYUK]ipsum [EGIK]dolar[/EGIK][/BUYUK][/KALIN]
_EOF;

$Content = Parse_Tag_EGIK_Recursive($Content);
$Content = Parse_Tag_KALIN_Recursive($Content);
$Content = Parse_Tag_BUYUK_Recursive($Content);

echo $Content;
?>