interface ThemeManagerInterface

interface ThemeManagerInterface {
    
    /**
     * Generates themed output.
     *
     * See the @link themeable Default theme implementations topic @endlink for
     * details.
     *
     * @param string $hook
     *   The name of the theme hook to call.
     * @param array $variables
     *   An associative array of theme variables.
     *
     * @return string|\Drupal\Component\Render\MarkupInterface
     *   The rendered output, or a Markup object.
     */
    public function render($hook, array $variables);
    
    /**
     * Returns the active theme object.
     *
     * @param \Drupal\Core\Routing\RouteMatchInterface|null $route_match
     *   The route match.
     *
     * @return \Drupal\Core\Theme\ActiveTheme
     */
    public function getActiveTheme(RouteMatchInterface $route_match = NULL);
    
    /**
     * Determines whether there is an active theme.
     *
     * @return bool
     */
    public function hasActiveTheme();
    
    /**
     * Resets the current active theme.
     *
     * Note: This method should not be used in common cases, just in special cases
     * like tests.
     *
     * @return $this
     */
    public function resetActiveTheme();
    
    /**
     * Sets the current active theme manually.
     *
     * Note: This method should not be used in common cases, just in special cases
     * like tests.
     *
     * @param \Drupal\Core\Theme\ActiveTheme $active_theme
     *   The new active theme.
     *
     * @return $this
     */
    public function setActiveTheme(ActiveTheme $active_theme);
    
    /**
     * Passes alterable variables to specific $theme_TYPE_alter() implementations.
     *
     * Executes an alter hook on the current theme. It also invokes alter hooks
     * for all base themes.
     *
     * $theme specifies the theme name of the active theme and all its base
     * themes.
     *
     * This dispatch function hands off the passed-in variables to type-specific
     * $theme_TYPE_alter() implementations in the active theme. It ensures a
     * consistent interface for all altering operations.
     *
     * A maximum of 2 alterable arguments is supported. In case more arguments
     * need to be passed and alterable, modules provide additional variables
     * assigned by reference in the last $context argument:
     * @code
     *   $context = array(
     *     'alterable' => &$alterable,
     *     'unalterable' => $unalterable,
     *     'foo' => 'bar',
     *   );
     *   $this->alter('mymodule_data', $alterable1, $alterable2, $context);
     * @endcode
     *
     * Note that objects are always passed by reference. If it is absolutely
     * required that no implementation alters a passed object in $context, then an
     * object needs to be cloned:
     * @code
     *   $context = array(
     *     'unalterable_object' => clone $object,
     *   );
     *   $this->alter('mymodule_data', $data, $context);
     * @endcode
     *
     * @param string|array $type
     *   A string describing the type of the alterable $data. 'form', 'links',
     *   'node_content', and so on are several examples. Alternatively can be an
     *   array, in which case $theme_TYPE_alter() is invoked for each value in the
     *   array. When Form API is using $this->alter() to
     *   execute both $theme_form_alter() and $theme_form_FORM_ID_alter()
     *   implementations, it passes array('form', 'form_' . $form_id) for $type.
     * @param mixed $data
     *   The variable that will be passed to $theme_TYPE_alter() implementations
     *   to be altered. The type of this variable depends on the value of the
     *   $type argument. For example, when altering a 'form', $data will be a
     *   structured array. When altering a 'profile', $data will be an object.
     * @param mixed $context1
     *   (optional) An additional variable that is passed by reference.
     * @param mixed $context2
     *   (optional) An additional variable that is passed by reference. If more
     *   context needs to be provided to implementations, then this should be an
     *   associative array as described above.
     *
     * @see \Drupal\Core\Extension\ModuleHandlerInterface
     */
    public function alter($type, &$data, &$context1 = NULL, &$context2 = NULL);
    
    /**
     * Provides an alter hook for a specific theme.
     *
     * Similar to ::alter, it also invokes the alter hooks for the base themes.
     *
     * @param \Drupal\Core\Theme\ActiveTheme $theme
     *   A manually specified theme.
     * @param string|array $type
     *   A string describing the type of the alterable $data.
     * @param mixed $data
     *   The variable that will be passed to $theme_TYPE_alter() implementations
     * @param mixed $context1
     *   (optional) An additional variable that is passed by reference.
     * @param mixed $context2
     *   (optional) An additional variable that is passed by reference.
     *
     * @see ::alter
     */
    public function alterForTheme(ActiveTheme $theme, $type, &$data, &$context1 = NULL, &$context2 = NULL);

}