interface TranslationInterface

interface TranslationInterface {
    
    /**
     * Translates a string to the current language or to a given language.
     *
     * Never call this translate() method directly. In order for strings to be
     * localized, make them available in one of the ways supported by the
     * @link https://www.drupal.org/node/322729 Localization API @endlink. When
     * possible, use the \Drupal\Core\StringTranslation\StringTranslationTrait
     * $this->t(). Otherwise create a new
     * \Drupal\Core\StringTranslation\TranslatableMarkup object.
     *
     * @param string $string
     *   A string containing the English text to translate.
     * @param array $args
     *   (optional) An associative array of replacements to make after
     *   translation. Based on the first character of the key, the value is
     *   escaped and/or themed. See
     *   \Drupal\Component\Render\FormattableMarkup::placeholderFormat() for
     *   details.
     * @param array $options
     *   (optional) An associative array of additional options, with the following
     *   elements:
     *   - 'langcode' (defaults to the current language): A language code, to
     *     translate to a language other than what is used to display the page.
     *   - 'context' (defaults to the empty context): The context the source
     *     string belongs to. See the
     *     @link i18n Internationalization topic @endlink for more information
     *     about string contexts.
     *
     * @return \Drupal\Core\StringTranslation\TranslatableMarkup
     *   An object that, when cast to a string, returns the translated string.
     *
     * @see \Drupal\Component\Render\FormattableMarkup::placeholderFormat()
     * @see \Drupal\Core\StringTranslation\TranslatableMarkup::__construct()
     *
     * @ingroup sanitization
     */
    public function translate($string, array $args = [], array $options = []);
    
    /**
     * Translates a TranslatableMarkup object to a string.
     *
     * @param \Drupal\Core\StringTranslation\TranslatableMarkup $translated_string
     *   A TranslatableMarkup object.
     *
     * @return string
     *   The translated string.
     */
    public function translateString(TranslatableMarkup $translated_string);
    
    /**
     * Formats a string containing a count of items.
     *
     * This function ensures that the string is pluralized correctly. Since
     * TranslationInterface::translate() is called by this function, make sure not
     * to pass already-localized strings to it. See
     * PluralTranslatableMarkup::createFromTranslatedString() for that.
     *
     * For example:
     * @code
     *   $output = $string_translation->formatPlural($node->comment_count, '1 comment', '@count comments');
     * @endcode
     *
     * Example with additional replacements:
     * @code
     *   $output = $string_translation->formatPlural($update_count,
     *     'Changed the content type of 1 post from %old-type to %new-type.',
     *     'Changed the content type of @count posts from %old-type to %new-type.',
     *     ['%old-type' => $info->old_type, '%new-type' => $info->new_type)];
     * @endcode
     *
     * @param int $count
     *   The item count to display.
     * @param string $singular
     *   The string for the singular case. Make sure it is clear this is singular,
     *   to ease translation (e.g. use "1 new comment" instead of "1 new"). Do not
     *   use @count in the singular string.
     * @param string $plural
     *   The string for the plural case. Make sure it is clear this is plural, to
     *   ease translation. Use @count in place of the item count, as in
     *   "@count new comments".
     * @param array $args
     *   An associative array of replacements to make after translation. Instances
     *   of any key in this array are replaced with the corresponding value.
     *   Based on the first character of the key, the value is escaped and/or
     *   themed. See \Drupal\Component\Render\FormattableMarkup. Note that you do
     *   not need to include @count in this array; this replacement is done
     *   automatically for the plural cases.
     * @param array $options
     *   An associative array of additional options. See t() for allowed keys.
     *
     * @return \Drupal\Core\StringTranslation\PluralTranslatableMarkup
     *   A translated string.
     *
     * @see \Drupal\Core\StringTranslation\TranslationInterface::translate()
     * @see t()
     * @see \Drupal\Component\Render\FormattableMarkup
     * @see \Drupal\Core\StringTranslation\PluralTranslatableMarkup::createFromTranslatedString()
     */
    public function formatPlural($count, $singular, $plural, array $args = [], array $options = []);

}