PHP function to make slug (URL string)

Question

function gen_slug($str){
    # special accents
    $a = array('À','Á','Â','Ã','Ä','Å','Æ','Ç','È','É','Ê','Ë','Ì','Í','Î','Ï','Ð','Ñ','Ò','Ó','Ô','Õ','Ö','Ø','Ù','Ú','Û','Ü','Ý','ß','à','á','â','ã','ä','å','æ','ç','è','é','ê','ë','ì','í','î','ï','ñ','ò','ó','ô','õ','ö','ø','ù','ú','û','ü','ý','ÿ','A','a','A','a','A','a','C','c','C','c','C','c','C','c','D','d','Ð','d','E','e','E','e','E','e','E','e','E','e','G','g','G','g','G','g','G','g','H','h','H','h','I','i','I','i','I','i','I','i','I','i','?','?','J','j','K','k','L','l','L','l','L','l','?','?','L','l','N','n','N','n','N','n','?','O','o','O','o','O','o','Œ','œ','R','r','R','r','R','r','S','s','S','s','S','s','Š','š','T','t','T','t','T','t','U','u','U','u','U','u','U','u','U','u','U','u','W','w','Y','y','Ÿ','Z','z','Z','z','Ž','ž','?','ƒ','O','o','U','u','A','a','I','i','O','o','U','u','U','u','U','u','U','u','U','u','?','?','?','?','?','?');
    $b = array('A','A','A','A','A','A','AE','C','E','E','E','E','I','I','I','I','D','N','O','O','O','O','O','O','U','U','U','U','Y','s','a','a','a','a','a','a','ae','c','e','e','e','e','i','i','i','i','n','o','o','o','o','o','o','u','u','u','u','y','y','A','a','A','a','A','a','C','c','C','c','C','c','C','c','D','d','D','d','E','e','E','e','E','e','E','e','E','e','G','g','G','g','G','g','G','g','H','h','H','h','I','i','I','i','I','i','I','i','I','i','IJ','ij','J','j','K','k','L','l','L','l','L','l','L','l','l','l','N','n','N','n','N','n','n','O','o','O','o','O','o','OE','oe','R','r','R','r','R','r','S','s','S','s','S','s','S','s','T','t','T','t','T','t','U','u','U','u','U','u','U','u','U','u','U','u','W','w','Y','y','Y','Z','z','Z','z','Z','z','s','f','O','o','U','u','A','a','I','i','O','o','U','u','U','u','U','u','U','u','U','u','A','a','AE','ae','O','o');
    return strtolower(preg_replace(array('/[^a-zA-Z0-9 -]/','/[ -]+/','/^-|-$/'),array('','-',''),str_replace($a,$b,$str)));
}

Works great, but I've found some cases in which it fails:

gen_slug('andrés') returns andras instead of andres

Why? Any ideas on the preg_replace parameters?

Answer 1

Don't use preg_replace for this. There's a php function built just for the task: strtr() http://php.net/manual/en/function.strtr.php

Taken from the comments in the above link (and I tested it myself; it works:

function normalize ($string) {
    $table = array(
        'Š'=>'S', 'š'=>'s', 'Đ'=>'Dj', 'đ'=>'dj', 'Ž'=>'Z', 'ž'=>'z', 'Č'=>'C', 'č'=>'c', 'Ć'=>'C', 'ć'=>'c',
        'À'=>'A', 'Á'=>'A', 'Â'=>'A', 'Ã'=>'A', 'Ä'=>'A', 'Å'=>'A', 'Æ'=>'A', 'Ç'=>'C', 'È'=>'E', 'É'=>'E',
        'Ê'=>'E', 'Ë'=>'E', 'Ì'=>'I', 'Í'=>'I', 'Î'=>'I', 'Ï'=>'I', 'Ñ'=>'N', 'Ò'=>'O', 'Ó'=>'O', 'Ô'=>'O',
        'Õ'=>'O', 'Ö'=>'O', 'Ø'=>'O', 'Ù'=>'U', 'Ú'=>'U', 'Û'=>'U', 'Ü'=>'U', 'Ý'=>'Y', 'Þ'=>'B', 'ß'=>'Ss',
        'à'=>'a', 'á'=>'a', 'â'=>'a', 'ã'=>'a', 'ä'=>'a', 'å'=>'a', 'æ'=>'a', 'ç'=>'c', 'è'=>'e', 'é'=>'e',
        'ê'=>'e', 'ë'=>'e', 'ì'=>'i', 'í'=>'i', 'î'=>'i', 'ï'=>'i', 'ð'=>'o', 'ñ'=>'n', 'ò'=>'o', 'ó'=>'o',
        'ô'=>'o', 'õ'=>'o', 'ö'=>'o', 'ø'=>'o', 'ù'=>'u', 'ú'=>'u', 'û'=>'u', 'ý'=>'y', 'ý'=>'y', 'þ'=>'b',
        'ÿ'=>'y', 'Ŕ'=>'R', 'ŕ'=>'r',
    );

    return strtr($string, $table);
}

Answer 2

Instead of a lengthy replace, try this one:

public static function slugify($text)
{
  // replace non letter or digits by -
  $text = preg_replace('~[^\pL\d]+~u', '-', $text);

  // transliterate
  $text = iconv('utf-8', 'us-ascii//TRANSLIT', $text);

  // remove unwanted characters
  $text = preg_replace('~[^-\w]+~', '', $text);

  // trim
  $text = trim($text, '-');

  // remove duplicate -
  $text = preg_replace('~-+~', '-', $text);

  // lowercase
  $text = strtolower($text);

  if (empty($text)) {
    return 'n-a';
  }

  return $text;
}

This was based off the one in Symfony's Jobeet tutorial.

Answer 3

You could have a look at Normalizer::normalize(), see here. It just needs to load the intl module for PHP

Answer 4

An updated version of @Imran Omar Bukhsh code (from the latest Wordpress (4.0) branch):

<?php

// Add methods to slugify taken from Wordpress:
// - https://github.com/WordPress/WordPress/blob/master/wp-includes/formatting.php 
// - https://github.com/WordPress/WordPress/blob/master/wp-includes/functions.php

/**
 * Set the mbstring internal encoding to a binary safe encoding when func_overload
 * is enabled.
 *
 * When mbstring.func_overload is in use for multi-byte encodings, the results from
 * strlen() and similar functions respect the utf8 characters, causing binary data
 * to return incorrect lengths.
 *
 * This function overrides the mbstring encoding to a binary-safe encoding, and
 * resets it to the users expected encoding afterwards through the
 * `reset_mbstring_encoding` function.
 *
 * It is safe to recursively call this function, however each
 * `mbstring_binary_safe_encoding()` call must be followed up with an equal number
 * of `reset_mbstring_encoding()` calls.
 *
 * @since 3.7.0
 *
 * @see reset_mbstring_encoding()
 *
 * @param bool $reset Optional. Whether to reset the encoding back to a previously-set encoding.
 *                    Default false.
 */
function mbstring_binary_safe_encoding( $reset = false ) {
  static $encodings = array();
  static $overloaded = null;

  if ( is_null( $overloaded ) )
    $overloaded = function_exists( 'mb_internal_encoding' ) && ( ini_get( 'mbstring.func_overload' ) & 2 );

  if ( false === $overloaded )
    return;

  if ( ! $reset ) {
    $encoding = mb_internal_encoding();
    array_push( $encodings, $encoding );
    mb_internal_encoding( 'ISO-8859-1' );
  }

  if ( $reset && $encodings ) {
    $encoding = array_pop( $encodings );
    mb_internal_encoding( $encoding );
  }
}

/**
 * Reset the mbstring internal encoding to a users previously set encoding.
 *
 * @see mbstring_binary_safe_encoding()
 *
 * @since 3.7.0
 */
function reset_mbstring_encoding() {
  mbstring_binary_safe_encoding( true );
}


/**
 * Checks to see if a string is utf8 encoded.
 *
 * NOTE: This function checks for 5-Byte sequences, UTF8
 *       has Bytes Sequences with a maximum length of 4.
 *
 * @author bmorel at ssi dot fr (modified)
 * @since 1.2.1
 *
 * @param string $str The string to be checked
 * @return bool True if $str fits a UTF-8 model, false otherwise.
 */
function seems_utf8($str) {
  mbstring_binary_safe_encoding();
  $length = strlen($str);
  reset_mbstring_encoding();
  for ($i=0; $i < $length; $i++) {
    $c = ord($str[$i]);
    if ($c < 0x80) $n = 0; # 0bbbbbbb
    elseif (($c & 0xE0) == 0xC0) $n=1; # 110bbbbb
    elseif (($c & 0xF0) == 0xE0) $n=2; # 1110bbbb
    elseif (($c & 0xF8) == 0xF0) $n=3; # 11110bbb
    elseif (($c & 0xFC) == 0xF8) $n=4; # 111110bb
    elseif (($c & 0xFE) == 0xFC) $n=5; # 1111110b
    else return false; # Does not match any model
    for ($j=0; $j<$n; $j++) { # n bytes matching 10bbbbbb follow ?
      if ((++$i == $length) || ((ord($str[$i]) & 0xC0) != 0x80))
        return false;
    }
  }
  return true;
}


/**
 * Encode the Unicode values to be used in the URI.
 *
 * @since 1.5.0
 *
 * @param string $utf8_string
 * @param int $length Max length of the string
 * @return string String with Unicode encoded for URI.
 */
function utf8_uri_encode( $utf8_string, $length = 0 ) {
  $unicode = '';
  $values = array();
  $num_octets = 1;
  $unicode_length = 0;

  mbstring_binary_safe_encoding();
  $string_length = strlen( $utf8_string );
  reset_mbstring_encoding();

  for ($i = 0; $i < $string_length; $i++ ) {

    $value = ord( $utf8_string[ $i ] );

    if ( $value < 128 ) {
      if ( $length && ( $unicode_length >= $length ) )
        break;
      $unicode .= chr($value);
      $unicode_length++;
    } else {
      if ( count( $values ) == 0 ) $num_octets = ( $value < 224 ) ? 2 : 3;

      $values[] = $value;

      if ( $length && ( $unicode_length + ($num_octets * 3) ) > $length )
        break;
      if ( count( $values ) == $num_octets ) {
        if ($num_octets == 3) {
          $unicode .= '%' . dechex($values[0]) . '%' . dechex($values[1]) . '%' . dechex($values[2]);
          $unicode_length += 9;
        } else {
          $unicode .= '%' . dechex($values[0]) . '%' . dechex($values[1]);
          $unicode_length += 6;
        }

        $values = array();
        $num_octets = 1;
      }
    }
  }

  return $unicode;
}


/**
 * Sanitizes a title, replacing whitespace and a few other characters with dashes.
 *
 * Limits the output to alphanumeric characters, underscore (_) and dash (-).
 * Whitespace becomes a dash.
 *
 * @since 1.2.0
 *
 * @param string $title The title to be sanitized.
 * @param string $raw_title Optional. Not used.
 * @param string $context Optional. The operation for which the string is sanitized.
 * @return string The sanitized title.
 */
function sanitize_title_with_dashes( $title, $raw_title = '', $context = 'display' ) {
  $title = strip_tags($title);
  // Preserve escaped octets.
  $title = preg_replace('|%([a-fA-F0-9][a-fA-F0-9])|', '---$1---', $title);
  // Remove percent signs that are not part of an octet.
  $title = str_replace('%', '', $title);
  // Restore octets.
  $title = preg_replace('|---([a-fA-F0-9][a-fA-F0-9])---|', '%$1', $title);

  if (seems_utf8($title)) {
    if (function_exists('mb_strtolower')) {
      $title = mb_strtolower($title, 'UTF-8');
    }
    $title = utf8_uri_encode($title, 200);
  }

  $title = strtolower($title);
  $title = preg_replace('/&.+?;/', '', $title); // kill entities
  $title = str_replace('.', '-', $title);

  if ( 'save' == $context ) {
    // Convert nbsp, ndash and mdash to hyphens
    $title = str_replace( array( '%c2%a0', '%e2%80%93', '%e2%80%94' ), '-', $title );

    // Strip these characters entirely
    $title = str_replace( array(
      // iexcl and iquest
      '%c2%a1', '%c2%bf',
      // angle quotes
      '%c2%ab', '%c2%bb', '%e2%80%b9', '%e2%80%ba',
      // curly quotes
      '%e2%80%98', '%e2%80%99', '%e2%80%9c', '%e2%80%9d',
      '%e2%80%9a', '%e2%80%9b', '%e2%80%9e', '%e2%80%9f',
      // copy, reg, deg, hellip and trade
      '%c2%a9', '%c2%ae', '%c2%b0', '%e2%80%a6', '%e2%84%a2',
      // acute accents
      '%c2%b4', '%cb%8a', '%cc%81', '%cd%81',
      // grave accent, macron, caron
      '%cc%80', '%cc%84', '%cc%8c',
    ), '', $title );

    // Convert times to x
    $title = str_replace( '%c3%97', 'x', $title );
  }

  $title = preg_replace('/[^%a-z0-9 _-]/', '', $title);
  $title = preg_replace('/\s+/', '-', $title);
  $title = preg_replace('|-+|', '-', $title);
  $title = trim($title, '-');

  return $title;
}

$title = '#PFW Alexander McQueen Spring/Summer 2015';
echo "title -> slug: \n". $title ." -> ". sanitize_title_with_dashes($title);
echo "\n\n";
$title = '«GQ»: Elyas M\'Barek gehört zu Männern des Jahres';
echo "title -> slug: \n". $title ." -> ". sanitize_title_with_dashes($title);

View online example.

Answer 5

The most elegant way I think is using a Behat\Transliterator\Transliterator.

I need to extends this class by your class because it is an Abstract, some like this:

<?php
use Behat\Transliterator\Transliterator;

class Urlizer extends Transliterator
{
}

And then, just use it:

$text = "Master Ápiu";
$urlizer = new Urlizer();
$slug = $urlizer->transliterate($slug, "-");
echo $slug; // master-apiu

Of course you should put this things in your composer as well.

composer require behat/transliterator

More info here https://github.com/Behat/Transliterator

Answer 6

it is always good idea to use existing solutions that are being supported by a lot of high level developers. The most popular one is https://github.com/cocur/slugify . First of all it supports more than one language and it is being updated.

If you do not want to use whole package you can just copy the part that you need.