Función PHP para hacer slug (cadena de URL)

Quiero tener una función para crear slugs a partir de cadenas Unicode, por ejemplo, gen_slug('Andrés Cortez')debería volver andres-cortez. ¿Cómo debo hacer eso?

En lugar de un reemplazo prolongado, prueba este:

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;
}

Esto se basó en el tutorial de Jobeet de Symfony.

Actualizar

Como esta respuesta está recibiendo algo de atención, estoy agregando alguna explicación.

La solución provista esencialmente reemplazará todo excepto AZ, az, 0-9, y - (guión) con - (guión). Por lo tanto, no funcionará correctamente con otros caracteres Unicode (que son caracteres válidos para una URL slug / string). Un escenario común es cuando la cadena de entrada contiene caracteres que no están en inglés.

Solo use esta solución si está seguro de que la cadena de entrada no tendrá caracteres Unicode que tal vez quiera formar parte de la salida / babosa.

P.ej. "नारी शक्ति" se convertirá en "----------" (todos los guiones) en lugar de "नारी-शक्ति" (slug de URL válido).

Respuesta original

Qué tal si...

$slug = strtolower(trim(preg_replace('/[^A-Za-z0-9-]+/', '-', $string)));

?

Si usted tiene instalada la extensión intl , puede usar la función Transliterator :: transliterate para crear una babosa fácilmente.

<?php
$string = 'Namnet på bildtävlingen';
$slug = \Transliterator::createFromRules(
    ':: Any-Latin;'
    . ':: NFD;'
    . ':: [:Nonspacing Mark:] Remove;'
    . ':: NFC;'
    . ':: [:Punctuation:] Remove;'
    . ':: Lower();'
    . '[:Separator:] > \'-\''
)
    ->transliterate( $string );
echo $slug; // namnet-pa-bildtavlingen
?>

Nota: ¡He tomado esto de WordPress y funciona!

Úselo así:

echo sanitize('testing this link');

Código

//taken from wordpress
function utf8_uri_encode( $utf8_string, $length = 0 ) {
    $unicode = '';
    $values = array();
    $num_octets = 1;
    $unicode_length = 0;

    $string_length = strlen( $utf8_string );
    for ($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;
}

//taken from wordpress
function seems_utf8($str) {
    $length = strlen($str);
    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;
}

//function sanitize_title_with_dashes taken from wordpress
function sanitize($title) {
    $title = strip_tags($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);
    $title = preg_replace('/[^%a-z0-9 _-]/', '', $title);
    $title = preg_replace('/\s+/', '-', $title);
    $title = preg_replace('|-+|', '-', $title);
    $title = trim($title, '-');

    return $title;
}

Siempre es una buena idea utilizar soluciones existentes que cuentan con el respaldo de muchos desarrolladores de alto nivel. El más popular es https://github.com/cocur/slugify . En primer lugar, admite más de un idioma y se está actualizando.

Si no desea utilizar el paquete completo, puede copiar la parte que necesita.

Aquí hay otro, por ejemplo "Título con caracteres extraños ééé AX Z" se convierte en "título con caracteres extraños-eee-axz".

/**
 * Function used to create a slug associated to an "ugly" string.
 *
 * @param string $string the string to transform.
 *
 * @return string the resulting slug.
 */
public static function createSlug($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', '/' => '-', ' ' => '-'
    );

    // -- Remove duplicated spaces
    $stripped = preg_replace(array('/\s{2,}/', '/[\t\n]/'), ' ', $string);

    // -- Returns the slug
    return strtolower(strtr($string, $table));


}

Una versión actualizada del código @Imran Omar Bukhsh (de la última rama de Wordpress (4.0)):

<?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);

Ver ejemplo en línea .

public static function slugify ($text) {

    $replace = [
        '<' => '', '>' => '', ''' => '', '&' => '',
        '"' => '', 'À' => 'A', 'Á' => 'A', 'Â' => 'A', 'Ã' => 'A', 'Ä'=> 'Ae',
        'Ä' => 'A', 'Å' => 'A', 'Ā' => 'A', 'Ą' => 'A', 'Ă' => 'A', 'Æ' => 'Ae',
        'Ç' => 'C', 'Ć' => 'C', 'Č' => 'C', 'Ĉ' => 'C', 'Ċ' => 'C', 'Ď' => 'D', 'Đ' => 'D',
        'Ð' => 'D', 'È' => 'E', 'É' => 'E', 'Ê' => 'E', 'Ë' => 'E', 'Ē' => 'E',
        'Ę' => 'E', 'Ě' => 'E', 'Ĕ' => 'E', 'Ė' => 'E', 'Ĝ' => 'G', 'Ğ' => 'G',
        'Ġ' => 'G', 'Ģ' => 'G', 'Ĥ' => 'H', 'Ħ' => 'H', 'Ì' => 'I', 'Í' => 'I',
        'Î' => 'I', 'Ï' => 'I', 'Ī' => 'I', 'Ĩ' => 'I', 'Ĭ' => 'I', 'Į' => 'I',
        'İ' => 'I', 'IJ' => 'IJ', 'Ĵ' => 'J', 'Ķ' => 'K', 'Ł' => 'K', 'Ľ' => 'K',
        'Ĺ' => 'K', 'Ļ' => 'K', 'Ŀ' => 'K', 'Ñ' => 'N', 'Ń' => 'N', 'Ň' => 'N',
        'Ņ' => 'N', 'Ŋ' => 'N', 'Ò' => 'O', 'Ó' => 'O', 'Ô' => 'O', 'Õ' => 'O',
        'Ö' => 'Oe', 'Ö' => 'Oe', 'Ø' => 'O', 'Ō' => 'O', 'Ő' => 'O', 'Ŏ' => 'O',
        'Œ' => 'OE', 'Ŕ' => 'R', 'Ř' => 'R', 'Ŗ' => 'R', 'Ś' => 'S', 'Š' => 'S',
        'Ş' => 'S', 'Ŝ' => 'S', 'Ș' => 'S', 'Ť' => 'T', 'Ţ' => 'T', 'Ŧ' => 'T',
        'Ț' => 'T', 'Ù' => 'U', 'Ú' => 'U', 'Û' => 'U', 'Ü' => 'Ue', 'Ū' => 'U',
        'Ü' => 'Ue', 'Ů' => 'U', 'Ű' => 'U', 'Ŭ' => 'U', 'Ũ' => 'U', 'Ų' => 'U',
        'Ŵ' => 'W', 'Ý' => 'Y', 'Ŷ' => 'Y', 'Ÿ' => 'Y', 'Ź' => 'Z', 'Ž' => 'Z',
        'Ż' => 'Z', 'Þ' => 'T', 'à' => 'a', 'á' => 'a', 'â' => 'a', 'ã' => 'a',
        'ä' => 'ae', 'ä' => 'ae', 'å' => 'a', 'ā' => 'a', 'ą' => 'a', 'ă' => 'a',
        'æ' => 'ae', 'ç' => 'c', 'ć' => 'c', 'č' => 'c', 'ĉ' => 'c', 'ċ' => 'c',
        'ď' => 'd', 'đ' => 'd', 'ð' => 'd', 'è' => 'e', 'é' => 'e', 'ê' => 'e',
        'ë' => 'e', 'ē' => 'e', 'ę' => 'e', 'ě' => 'e', 'ĕ' => 'e', 'ė' => 'e',
        'ƒ' => 'f', 'ĝ' => 'g', 'ğ' => 'g', 'ġ' => 'g', 'ģ' => 'g', 'ĥ' => 'h',
        'ħ' => 'h', 'ì' => 'i', 'í' => 'i', 'î' => 'i', 'ï' => 'i', 'ī' => 'i',
        'ĩ' => 'i', 'ĭ' => 'i', 'į' => 'i', 'ı' => 'i', 'ij' => 'ij', 'ĵ' => 'j',
        'ķ' => 'k', 'ĸ' => 'k', 'ł' => 'l', 'ľ' => 'l', 'ĺ' => 'l', 'ļ' => 'l',
        'ŀ' => 'l', 'ñ' => 'n', 'ń' => 'n', 'ň' => 'n', 'ņ' => 'n', 'ʼn' => 'n',
        'ŋ' => 'n', 'ò' => 'o', 'ó' => 'o', 'ô' => 'o', 'õ' => 'o', 'ö' => 'oe',
        'ö' => 'oe', 'ø' => 'o', 'ō' => 'o', 'ő' => 'o', 'ŏ' => 'o', 'œ' => 'oe',
        'ŕ' => 'r', 'ř' => 'r', 'ŗ' => 'r', 'š' => 's', 'ù' => 'u', 'ú' => 'u',
        'û' => 'u', 'ü' => 'ue', 'ū' => 'u', 'ü' => 'ue', 'ů' => 'u', 'ű' => 'u',
        'ŭ' => 'u', 'ũ' => 'u', 'ų' => 'u', 'ŵ' => 'w', 'ý' => 'y', 'ÿ' => 'y',
        'ŷ' => 'y', 'ž' => 'z', 'ż' => 'z', 'ź' => 'z', 'þ' => 't', 'ß' => 'ss',
        'ſ' => 'ss', 'ый' => 'iy', 'А' => 'A', 'Б' => 'B', 'В' => 'V', 'Г' => 'G',
        'Д' => 'D', 'Е' => 'E', 'Ё' => 'YO', 'Ж' => 'ZH', 'З' => 'Z', 'И' => 'I',
        'Й' => 'Y', 'К' => 'K', 'Л' => 'L', 'М' => 'M', 'Н' => 'N', 'О' => 'O',
        'П' => 'P', 'Р' => 'R', 'С' => 'S', 'Т' => 'T', 'У' => 'U', 'Ф' => 'F',
        'Х' => 'H', 'Ц' => 'C', 'Ч' => 'CH', 'Ш' => 'SH', 'Щ' => 'SCH', 'Ъ' => '',
        'Ы' => 'Y', 'Ь' => '', 'Э' => 'E', 'Ю' => 'YU', 'Я' => 'YA', 'а' => 'a',
        'б' => 'b', 'в' => 'v', 'г' => 'g', 'д' => 'd', 'е' => 'e', 'ё' => 'yo',
        'ж' => 'zh', 'з' => 'z', 'и' => 'i', 'й' => 'y', 'к' => 'k', 'л' => 'l',
        'м' => 'm', 'н' => 'n', 'о' => 'o', 'п' => 'p', 'р' => 'r', 'с' => 's',
        'т' => 't', 'у' => 'u', 'ф' => 'f', 'х' => 'h', 'ц' => 'c', 'ч' => 'ch',
        'ш' => 'sh', 'щ' => 'sch', 'ъ' => '', 'ы' => 'y', 'ь' => '', 'э' => 'e',
        'ю' => 'yu', 'я' => 'ya'
    ];

    // make a human readable string
    $text = strtr($text, $replace);

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

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

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

    $text = strtolower($text);

    return $text;
}

No use preg_replace para esto. Hay una función php creada solo para la tarea: strtr () http://php.net/manual/en/function.strtr.php

Tomado de los comentarios en el enlace anterior (y lo probé yo mismo; funciona:

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);
}

Estoy usando:

function slugify($text)
{ 
    $text = iconv('utf-8', 'us-ascii//TRANSLIT', $text);
    return strtolower(preg_replace('/[^A-Za-z0-9-]+/', '-', $text));
}

El único inconveniente es que los caracteres cirílicos no se convertirán, y ahora estoy buscando una solución que no sea larga para reemplazar cada carácter cirílico.

No sabía cuál usar, así que hice un banco rápido en phptester.net

<?php

// First test
// https://stackoverflow.com/a/42740874/10232729
function slugify(STRING $string, STRING $separator = '-'){
    
    $accents_regex = '~&([a-z]{1,2})(?:acute|cedil|circ|grave|lig|orn|ring|slash|th|tilde|uml);~i';
    $special_cases = [ '&' => 'and', "'" => ''];
    $string = mb_strtolower( trim( $string ), 'UTF-8' );
    $string = str_replace( array_keys($special_cases), array_values( $special_cases), $string );
    $string = preg_replace( $accents_regex, '$1', htmlentities( $string, ENT_QUOTES, 'UTF-8' ) );
    $string = preg_replace('/[^a-z0-9]/u', $separator, $string);
    
    return preg_replace('/['.$separator.']+/u', $separator, $string);
}

// Second test
// https://stackoverflow.com/a/13331948/10232729
function slug(STRING $string, STRING $separator = '-'){
    
    $string = transliterator_transliterate('Any-Latin; NFD; [:Nonspacing Mark:] Remove; NFC; [:Punctuation:] Remove; Lower();', $string);
        
    return str_replace(' ', $separator, $string);;
}

// Third test - My choice
// https://stackoverflow.com/a/38066136/10232729
function slugbis($text){

    $replace = [
        '<' => '', '>' => '', '-' => ' ', '&' => '',
        '"' => '', 'À' => 'A', 'Á' => 'A', 'Â' => 'A', 'Ã' => 'A', 'Ä'=> 'Ae',
        'Ä' => 'A', 'Å' => 'A', 'Ā' => 'A', 'Ą' => 'A', 'Ă' => 'A', 'Æ' => 'Ae',
        'Ç' => 'C', 'Ć' => 'C', 'Č' => 'C', 'Ĉ' => 'C', 'Ċ' => 'C', 'Ď' => 'D', 'Đ' => 'D',
        'Ð' => 'D', 'È' => 'E', 'É' => 'E', 'Ê' => 'E', 'Ë' => 'E', 'Ē' => 'E',
        'Ę' => 'E', 'Ě' => 'E', 'Ĕ' => 'E', 'Ė' => 'E', 'Ĝ' => 'G', 'Ğ' => 'G',
        'Ġ' => 'G', 'Ģ' => 'G', 'Ĥ' => 'H', 'Ħ' => 'H', 'Ì' => 'I', 'Í' => 'I',
        'Î' => 'I', 'Ï' => 'I', 'Ī' => 'I', 'Ĩ' => 'I', 'Ĭ' => 'I', 'Į' => 'I',
        'İ' => 'I', 'IJ' => 'IJ', 'Ĵ' => 'J', 'Ķ' => 'K', 'Ł' => 'K', 'Ľ' => 'K',
        'Ĺ' => 'K', 'Ļ' => 'K', 'Ŀ' => 'K', 'Ñ' => 'N', 'Ń' => 'N', 'Ň' => 'N',
        'Ņ' => 'N', 'Ŋ' => 'N', 'Ò' => 'O', 'Ó' => 'O', 'Ô' => 'O', 'Õ' => 'O',
        'Ö' => 'Oe', 'Ö' => 'Oe', 'Ø' => 'O', 'Ō' => 'O', 'Ő' => 'O', 'Ŏ' => 'O',
        'Œ' => 'OE', 'Ŕ' => 'R', 'Ř' => 'R', 'Ŗ' => 'R', 'Ś' => 'S', 'Š' => 'S',
        'Ş' => 'S', 'Ŝ' => 'S', 'Ș' => 'S', 'Ť' => 'T', 'Ţ' => 'T', 'Ŧ' => 'T',
        'Ț' => 'T', 'Ù' => 'U', 'Ú' => 'U', 'Û' => 'U', 'Ü' => 'Ue', 'Ū' => 'U',
        'Ü' => 'Ue', 'Ů' => 'U', 'Ű' => 'U', 'Ŭ' => 'U', 'Ũ' => 'U', 'Ų' => 'U',
        'Ŵ' => 'W', 'Ý' => 'Y', 'Ŷ' => 'Y', 'Ÿ' => 'Y', 'Ź' => 'Z', 'Ž' => 'Z',
        'Ż' => 'Z', 'Þ' => 'T', 'à' => 'a', 'á' => 'a', 'â' => 'a', 'ã' => 'a',
        'ä' => 'ae', 'ä' => 'ae', 'å' => 'a', 'ā' => 'a', 'ą' => 'a', 'ă' => 'a',
        'æ' => 'ae', 'ç' => 'c', 'ć' => 'c', 'č' => 'c', 'ĉ' => 'c', 'ċ' => 'c',
        'ď' => 'd', 'đ' => 'd', 'ð' => 'd', 'è' => 'e', 'é' => 'e', 'ê' => 'e',
        'ë' => 'e', 'ē' => 'e', 'ę' => 'e', 'ě' => 'e', 'ĕ' => 'e', 'ė' => 'e',
        'ƒ' => 'f', 'ĝ' => 'g', 'ğ' => 'g', 'ġ' => 'g', 'ģ' => 'g', 'ĥ' => 'h',
        'ħ' => 'h', 'ì' => 'i', 'í' => 'i', 'î' => 'i', 'ï' => 'i', 'ī' => 'i',
        'ĩ' => 'i', 'ĭ' => 'i', 'į' => 'i', 'ı' => 'i', 'ij' => 'ij', 'ĵ' => 'j',
        'ķ' => 'k', 'ĸ' => 'k', 'ł' => 'l', 'ľ' => 'l', 'ĺ' => 'l', 'ļ' => 'l',
        'ŀ' => 'l', 'ñ' => 'n', 'ń' => 'n', 'ň' => 'n', 'ņ' => 'n', 'ʼn' => 'n',
        'ŋ' => 'n', 'ò' => 'o', 'ó' => 'o', 'ô' => 'o', 'õ' => 'o', 'ö' => 'oe',
        'ö' => 'oe', 'ø' => 'o', 'ō' => 'o', 'ő' => 'o', 'ŏ' => 'o', 'œ' => 'oe',
        'ŕ' => 'r', 'ř' => 'r', 'ŗ' => 'r', 'š' => 's', 'ù' => 'u', 'ú' => 'u',
        'û' => 'u', 'ü' => 'ue', 'ū' => 'u', 'ü' => 'ue', 'ů' => 'u', 'ű' => 'u',
        'ŭ' => 'u', 'ũ' => 'u', 'ų' => 'u', 'ŵ' => 'w', 'ý' => 'y', 'ÿ' => 'y',
        'ŷ' => 'y', 'ž' => 'z', 'ż' => 'z', 'ź' => 'z', 'þ' => 't', 'ß' => 'ss',
        'ſ' => 'ss', 'ый' => 'iy', 'А' => 'A', 'Б' => 'B', 'В' => 'V', 'Г' => 'G',
        'Д' => 'D', 'Е' => 'E', 'Ё' => 'YO', 'Ж' => 'ZH', 'З' => 'Z', 'И' => 'I',
        'Й' => 'Y', 'К' => 'K', 'Л' => 'L', 'М' => 'M', 'Н' => 'N', 'О' => 'O',
        'П' => 'P', 'Р' => 'R', 'С' => 'S', 'Т' => 'T', 'У' => 'U', 'Ф' => 'F',
        'Х' => 'H', 'Ц' => 'C', 'Ч' => 'CH', 'Ш' => 'SH', 'Щ' => 'SCH', 'Ъ' => '',
        'Ы' => 'Y', 'Ь' => '', 'Э' => 'E', 'Ю' => 'YU', 'Я' => 'YA', 'а' => 'a',
        'б' => 'b', 'в' => 'v', 'г' => 'g', 'д' => 'd', 'е' => 'e', 'ё' => 'yo',
        'ж' => 'zh', 'з' => 'z', 'и' => 'i', 'й' => 'y', 'к' => 'k', 'л' => 'l',
        'м' => 'm', 'н' => 'n', 'о' => 'o', 'п' => 'p', 'р' => 'r', 'с' => 's',
        'т' => 't', 'у' => 'u', 'ф' => 'f', 'х' => 'h', 'ц' => 'c', 'ч' => 'ch',
        'ш' => 'sh', 'щ' => 'sch', 'ъ' => '', 'ы' => 'y', 'ь' => '', 'э' => 'e',
        'ю' => 'yu', 'я' => 'ya'
    ];

    // make a human readable string
    $text = strtr($text, $replace);

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

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

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

    return strtolower($text);
}

// Fourth test
// https://stackoverflow.com/a/2955521/10232729
function slugagain($string){
    
    $table = [
        '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);
}

// Fifth test
// https://stackoverflow.com/a/27396804/10232729
function slugifybis($url){
    $url = trim($url);

    $url = str_replace(' ', '-', $url);
    $url = str_replace('/', '-slash-', $url);
    
    return rawurlencode($url);
}

// Sixth and last test
// https://stackoverflow.com/a/39442034/10232729
setlocale( LC_ALL, "en_US.UTF8" );  
function slugifyagain($string){
    
    $string = iconv('utf-8', 'us-ascii//translit//ignore', $string); // transliterate
    $string = str_replace("'", '', $string);
    $string = preg_replace('~[^\pL\d]+~u', '-', $string); // replace non letter or non digits by "-"
    $string = preg_replace('~[^-\w]+~', '', $string); // remove unwanted characters
    $string = preg_replace('~-+~', '-', $string); // remove duplicate "-"
    $string = trim($string, '-'); // trim "-"
    $string = trim($string); // trim
    $string = mb_strtolower($string, 'utf-8'); // lowercase
    
    return urlencode($string); // safe;
};

$string = $newString = "¿ Àñdréß l'affreux ğarçon & nøël en forêt !";

$max = 10000;

echo '<pre>';
echo 'Beginning :';
echo '<br />';
echo '<br />';    
echo '> Slugging '.$max.' iterations of following :';
echo '<br />';
echo '>> ' . $string;
echo '<br />';  
echo '<br />';
echo 'Output results :';
echo '<br />';
echo '<br />';  

$start = microtime(true);

for($i = 0 ; $i < $max ; $i++){
    
    $newString = slugify($string);
}

$time = (microtime(true) - $start) * 1000;

echo '> First test passed in **' . round($time, 2) . 'ms**';
echo '<br />';  
echo '>> Result : ' . $newString;
echo '<br />';
echo '<br />';

$start = microtime(true);

for($i = 0 ; $i < $max ; $i++){
    
    $newString = slug($string);
}

$time = (microtime(true) - $start) * 1000;

echo '> Second test passed in **' . round($time, 2) . 'ms**';
echo '<br />';
echo '>> Result : ' . $newString;
echo '<br />';
echo '<br />';

$start = microtime(true);

for($i = 0 ; $i < $max ; $i++){
    
    $newString = slugbis($string);
}

$time = (microtime(true) - $start) * 1000;

echo '> Third test passed in **' . round($time, 2) . 'ms**';
echo '<br />';
echo '>> Result : ' . $newString;
echo '<br />';
echo '<br />';

$start = microtime(true);

for($i = 0 ; $i < $max ; $i++){
    
    $newString = slugagain($string);
}

$time = (microtime(true) - $start) * 1000;

echo '> Fourth test passed in **' . round($time, 2) . 'ms**';
echo '<br />';
echo '>> Result : ' . $newString;
echo '<br />';
echo '<br />';

$start = microtime(true);

for($i = 0 ; $i < $max ; $i++){
    
    $newString = slugifybis($string);
}

$time = (microtime(true) - $start) * 1000;

echo '> Fifth test passed in **' . round($time, 2) . 'ms**';
echo '<br />';
echo '>> Result : ' . $newString;
echo '<br />';
echo '<br />';

$start = microtime(true);

for($i = 0 ; $i < $max ; $i++){
    
    $newString = slugifyagain($string);
}

$time = (microtime(true) - $start) * 1000;

echo '> Sixth test passed in **' . round($time, 2) . 'ms**';
echo '<br />';
echo '>> Result : ' . $newString;
echo '</pre>';