interface FieldHandlerInterface

interface FieldHandlerInterface extends ViewsHandlerInterface {
    
    /**
     * Adds an ORDER BY clause to the query for click sort columns.
     *
     * @param string $order
     *   The sort order, either 'ASC' or 'DESC'.
     */
    public function clickSort($order);
    
    /**
     * Determines if this field is click sortable.
     *
     * @return bool
     *   The value of 'click sortable' from the plugin definition, this defaults
     *   to TRUE if not set.
     */
    public function clickSortable();
    
    /**
     * Gets this field's label.
     */
    public function label();
    
    /**
     * Returns an HTML element based upon the field's element type.
     *
     * @param bool $none_supported
     *   (optional) Whether or not this HTML element is supported. Defaults to
     *   FALSE.
     * @param bool $default_empty
     *   (optional) Whether or not this HTML element is empty by default. Defaults
     *   to FALSE.
     * @param bool $inline
     *   (optional) Whether or not this HTML element is inline. Defaults to FALSE.
     */
    public function elementType($none_supported = FALSE, $default_empty = FALSE, $inline = FALSE);
    
    /**
     * Returns an HTML element for the label based upon the field's element type.
     *
     * @param bool $none_supported
     *   (optional) Whether or not this HTML element is supported. Defaults to
     *   FALSE.
     * @param bool $default_empty
     *   (optional) Whether or not this HTML element is empty by default. Defaults
     *   to FALSE.
     */
    public function elementLabelType($none_supported = FALSE, $default_empty = FALSE);
    
    /**
     * Returns a wrapper HTML element for the field..
     *
     * @param bool $none_supported
     *   (optional) Whether or not this HTML element is supported. Defaults to
     *   FALSE.
     * @param bool $default_empty
     *   (optional) Whether or not this HTML element is empty by default. Defaults
     *   to FALSE.
     */
    public function elementWrapperType($none_supported = FALSE, $default_empty = FALSE);
    
    /**
     * Provides a list of elements valid for field HTML.
     *
     * This function can be overridden by fields that want more or fewer elements
     * available, though this seems like it would be an incredibly rare
     * occurrence.
     */
    public function getElements();
    
    /**
     * Returns the class of the field.
     *
     * @param int|null $row_index
     *   (optional) Index of the row element. If NULL the last row is used.
     *   Defaults to NULL.
     */
    public function elementClasses($row_index = NULL);
    
    /**
     * Replaces a value with tokens from the last field.
     *
     * This function actually figures out which field was last and uses its
     * tokens so they will all be available.
     *
     * @param string $value
     *   The raw string.
     * @param int|null $row_index
     *   (optional) Index of the row element. If NULL the last row is used.
     *   Defaults to NULL.
     */
    public function tokenizeValue($value, $row_index = NULL);
    
    /**
     * Returns the class of the field's label.
     *
     * @param int|null $row_index
     *   (optional) Index of the row element. If NULL the last row is used.
     *   Defaults to NULL.
     */
    public function elementLabelClasses($row_index = NULL);
    
    /**
     * Returns the class of the field's wrapper.
     *
     * @param int|null $row_index
     *   (optional) Index of the row element. If NULL the last row is used.
     *   Defaults to NULL.
     */
    public function elementWrapperClasses($row_index = NULL);
    
    /**
     * Gets the entity matching the current row and relationship.
     *
     * @param \Drupal\views\ResultRow $values
     *   An object containing all retrieved values.
     *
     * @return \Drupal\Core\Entity\EntityInterface|null
     *   Returns the entity matching the values or NULL if there is no matching
     *   entity.
     */
    public function getEntity(ResultRow $values);
    
    /**
     * Gets the value that's supposed to be rendered.
     *
     * This api exists so that other modules can easy set the values of the field
     * without having the need to change the render method as well.
     *
     * @param \Drupal\views\ResultRow $values
     *   An object containing all retrieved values.
     * @param string|null $field
     *   (optional) Index of the row element. If NULL the last row is used.
     *   Defaults to NULL.
     *
     * @return mixed
     *   The value to be rendered.
     */
    public function getValue(ResultRow $values, $field = NULL);
    
    /**
     * Determines if this field can be grouped in the results.
     *
     * @return bool
     *   TRUE if this field handler is groupable, otherwise FALSE.
     */
    public function useStringGroupBy();
    
    /**
     * Runs before any fields are rendered.
     *
     * This gives the handlers some time to set up before any handler has been
     * rendered.
     *
     * @param \Drupal\views\ResultRow[] $values
     *   An array of all ResultRow objects returned from the query.
     */
    public function preRender(&$values);
    
    /**
     * Renders the field.
     *
     * @param \Drupal\views\ResultRow $values
     *   The values retrieved from a single row of a view's query result.
     *
     * @return string|\Drupal\Component\Render\MarkupInterface
     *   The rendered output. If the output is safe it will be wrapped in an
     *   object that implements MarkupInterface. If it is empty or unsafe it
     *   will be a string.
     */
    public function render(ResultRow $values);
    
    /**
     * Runs after every field has been rendered.
     *
     * This is meant to be used mainly to deal with field handlers whose output
     * cannot be cached at row level but can be cached at display level. The
     * typical example is the row counter. For completely uncacheable field output
     * placeholders should be used.
     *
     * @param \Drupal\views\ResultRow $row
     *   An array of all ResultRow objects returned from the query.
     * @param $output
     *   The field rendered output.
     *
     * @return string[]
     *   An associative array of post-render token values keyed by placeholder.
     *
     * @see \Drupal\views\Plugin\views\field\UncacheableFieldHandlerTrait
     */
    public function postRender(ResultRow $row, $output);
    
    /**
     * Renders a field using advanced settings.
     *
     * This renders a field normally, then decides if render-as-link and
     * text-replacement rendering is necessary.
     *
     * @param \Drupal\views\ResultRow $values
     *   The values retrieved from a single row of a view's query result.
     *
     * @return \Drupal\Component\Render\MarkupInterface|string
     *   The advanced rendered output. If the output is safe, it will be wrapped
     *   in an object that implements MarkupInterface. If it is empty or unsafe,
     *   it will be a string.
     */
    public function advancedRender(ResultRow $values);
    
    /**
     * Checks if a field value is empty.
     *
     * @param $value
     *   The field value.
     * @param bool $empty_zero
     *   Whether or not this field is configured to consider 0 as empty.
     * @param bool $no_skip_empty
     *   (optional) Whether or not to use empty() to check the value. Defaults to
     *   TRUE.
     *
     * @return bool
     *   TRUE if the value is considered empty, FALSE otherwise.
     */
    public function isValueEmpty($value, $empty_zero, $no_skip_empty = TRUE);
    
    /**
     * Performs an advanced text render for the item.
     *
     * This is separated out as some fields may render lists, and this allows each
     * item to be handled individually.
     *
     * @param array $alter
     *   The alter array of options to use:
     *   - max_length: Maximum length of a string, the rest gets truncated.
     *   - word_boundary: Trim only on a word boundary.
     *   - ellipsis: Show an ellipsis at the end of the trimmed string.
     *   - html: Make sure that the HTML is correct.
     *
     * @return \Drupal\Component\Render\MarkupInterface|string
     *   The rendered output. If the output is safe it will be wrapped in an
     *   object that implements MarkupInterface. If it is empty or unsafe it will
     *   be a string.
     */
    public function renderText($alter);
    
    /**
     * Gets the 'render' tokens to use for advanced rendering.
     *
     * This runs through all of the fields and arguments that are available and
     * gets their values. This will then be used in one giant str_replace().
     *
     * @param mixed $item
     *   The item to render.
     *
     * @return array
     *   An array of available tokens
     */
    public function getRenderTokens($item);
    
    /**
     * Renders row values using $this->themeFunctions() as #theme.
     *
     * @param \Drupal\views\ResultRow $values
     *   Holds single row of a view's result set.
     *
     * @return \Drupal\Component\Render\MarkupInterface|string
     *   Returns rendered output of the given theme implementation. If the output
     *   is safe, it will be wrapped in an object that implements MarkupInterface.
     *   If it is empty or unsafe, it will be a string.
     */
    public function theme(ResultRow $values);

}