PHP slug function

slug.php

<?php

// Extracted from the Laravel Framework (http://laravel.com)

function toSlug($title, $separator = '-', $to_lower = true) {
  // Convert all dashes/underscores into separator
  $flip = $separator == '-' ? '_' : '-';

  $title = preg_replace('!['.preg_quote($flip).']+!u', $separator, $title);

  if ($to_lower) {
    $title = mb_strtolower($title);
  }

  // Remove all characters that are not the separator, letters, numbers, or whitespace.
  $title = preg_replace('![^'.preg_quote($separator).'\pL\pN\s]+!u', '', $title);

  // Replace all separator characters and whitespace by a single separator
  $title = preg_replace('!['.preg_quote($separator).'\s]+!u', $separator, $title);

  return trim($title, $separator);
}