interface TransliterationInterface

interface TransliterationInterface {
    
    /**
     * Removes diacritics (accents) from certain letters.
     *
     * This only applies to certain letters: Accented Latin characters like
     * a-with-acute-accent, in the UTF-8 character range of 0xE0 to 0xE6 and
     * 01CD to 024F. Replacements that would result in the string changing length
     * are excluded, as well as characters that are not accented US-ASCII letters.
     *
     * @param string $string
     *   The string holding diacritics.
     *
     * @return string
     *   $string with accented letters replaced by their unaccented equivalents.
     */
    public function removeDiacritics($string);
    
    /**
     * Transliterates text from Unicode to US-ASCII.
     *
     * @param string $string
     *   The string to transliterate.
     * @param string $langcode
     *   (optional) The language code of the language the string is in. Defaults
     *   to 'en' if not provided. Warning: this can be unfiltered user input.
     * @param string $unknown_character
     *   (optional) The character to substitute for characters in $string without
     *   transliterated equivalents. Defaults to '?'.
     * @param int $max_length
     *   (optional) If provided, return at most this many characters, ensuring
     *   that the transliteration does not split in the middle of an input
     *   character's transliteration.
     *
     * @return string
     *   $string with non-US-ASCII characters transliterated to US-ASCII
     *   characters, and unknown characters replaced with $unknown_character.
     */
    public function transliterate($string, $langcode = 'en', $unknown_character = '?', $max_length = NULL);

}