Function which create a slug from string

Slug

<?php

function slug($str, $delimiter='-', $charset='utf-8') {
    $str = preg_replace("`\[.*\]`U","",$str);
    $str = preg_replace('`&(amp;)?#?[a-z0-9]+;`i','-',$str);
    $str = htmlentities($str, ENT_NOQUOTES, $charset);
    $str = preg_replace( "`&([a-z])(acute|uml|circ|grave|ring|cedil|slash|tilde|caron|lig);`i","\\1", $str );
    $str = preg_replace( array("`[^a-z0-9]`i","`[-]+`") , "-", $str);
    $str = ( $str == "" ) ? $type : strtolower(trim($str, '-'));
    $str = strtolower($str);

    return $str;
}