interface EntityViewBuilderInterface

interface EntityViewBuilderInterface {
    
    /**
     * Builds the component fields and properties of a set of entities.
     *
     * @param &$build
     *   The renderable array representing the entity content.
     * @param \Drupal\Core\Entity\EntityInterface[] $entities
     *   The entities whose content is being built.
     * @param \Drupal\Core\Entity\Display\EntityViewDisplayInterface[] $displays
     *   The array of entity view displays holding the display options
     *   configured for the entity components, keyed by bundle name.
     * @param string $view_mode
     *   The view mode in which the entity is being viewed.
     */
    public function buildComponents(array &$build, array $entities, array $displays, $view_mode);
    
    /**
     * Builds the render array for the provided entity.
     *
     * @param \Drupal\Core\Entity\EntityInterface $entity
     *   The entity to render.
     * @param string $view_mode
     *   (optional) The view mode that should be used to render the entity.
     * @param string $langcode
     *   (optional) For which language the entity should be rendered, defaults to
     *   the current content language.
     *
     * @return array
     *   A render array for the entity.
     *
     * @throws \InvalidArgumentException
     *   Can be thrown when the set of parameters is inconsistent, like when
     *   trying to view a Comment and passing a Node which is not the one the
     *   comment belongs to, or not passing one, and having the comment node not
     *   be available for loading.
     */
    public function view(EntityInterface $entity, $view_mode = 'full', $langcode = NULL);
    
    /**
     * Builds the render array for the provided entities.
     *
     * @param array $entities
     *   An array of entities implementing EntityInterface to view.
     * @param string $view_mode
     *   (optional) The view mode that should be used to render the entity.
     * @param string $langcode
     *   (optional) For which language the entity should be rendered, defaults to
     *   the current content language.
     *
     * @return
     *   A render array for the entities, indexed by the same keys as the
     *   entities array passed in $entities.
     *
     * @throws \InvalidArgumentException
     *   Can be thrown when the set of parameters is inconsistent, like when
     *   trying to view Comments and passing a Node which is not the one the
     *   comments belongs to, or not passing one, and having the comments node not
     *   be available for loading.
     */
    public function viewMultiple(array $entities = [], $view_mode = 'full', $langcode = NULL);
    
    /**
     * Resets the entity render cache.
     *
     * @param \Drupal\Core\Entity\EntityInterface[] $entities
     *   (optional) If specified, the cache is reset for the given entities only.
     */
    public function resetCache(array $entities = NULL);
    
    /**
     * Builds a renderable array for the value of a single field in an entity.
     *
     * The resulting output is a fully themed field with label and multiple
     * values.
     *
     * This function can be used by third-party modules that need to output an
     * isolated field.
     * - Do not use inside node (or any other entity) templates; use
     *   render($content[FIELD_NAME]) instead.
     * - The FieldItemInterface::view() method can be used to output a single
     *   formatted field value, without label or wrapping field markup.
     *
     * The function takes care of invoking the prepare_view steps. It also
     * respects field access permissions.
     *
     * @param \Drupal\Core\Field\FieldItemListInterface $items
     *   FieldItemList containing the values to be displayed.
     * @param string|array $display_options
     *   Can be either:
     *   - The name of a view mode. The field will be displayed according to the
     *     display settings specified for this view mode in the $field
     *     definition for the field in the entity's bundle. If no display settings
     *     are found for the view mode, the settings for the 'default' view mode
     *     will be used.
     *   - An array of display options. The following key/value pairs are allowed:
     *     - label: (string) Position of the label. The default 'field' theme
     *       implementation supports the values 'inline', 'above' and 'hidden'.
     *       Defaults to 'above'.
     *     - type: (string) The formatter to use. Defaults to the
     *       'default_formatter' for the field type. The default formatter will
     *       also be used if the requested formatter is not available.
     *     - settings: (array) Settings specific to the formatter. Defaults to the
     *       formatter's default settings.
     *     - weight: (float) The weight to assign to the renderable element.
     *       Defaults to 0.
     *
     * @return array
     *   A renderable array for the field values.
     *
     * @see \Drupal\Core\Entity\EntityViewBuilderInterface::viewFieldItem()
     */
    public function viewField(FieldItemListInterface $items, $display_options = []);
    
    /**
     * Builds a renderable array for a single field item.
     *
     * @param \Drupal\Core\Field\FieldItemInterface $item
     *   FieldItem to be displayed.
     * @param string|array $display_options
     *   Can be either the name of a view mode, or an array of display settings.
     *   See EntityViewBuilderInterface::viewField() for more information.
     *
     * @return array
     *   A renderable array for the field item.
     *
     * @see \Drupal\Core\Entity\EntityViewBuilderInterface::viewField()
     */
    public function viewFieldItem(FieldItemInterface $item, $display_options = []);
    
    /**
     * The cache tag associated with this entity view builder.
     *
     * An entity view builder is instantiated on a per-entity type basis, so the
     * cache tags are also per-entity type.
     *
     * @return array
     *   An array of cache tags.
     */
    public function getCacheTags();

}