interface SectionListInterface

interface SectionListInterface extends \Countable {
    
    /**
     * Gets the layout sections.
     *
     * @return \Drupal\layout_builder\Section[]
     *   A sequentially and numerically keyed array of section objects.
     */
    public function getSections();
    
    /**
     * Gets a domain object for the layout section.
     *
     * @param int $delta
     *   The delta of the section.
     *
     * @return \Drupal\layout_builder\Section
     *   The layout section.
     */
    public function getSection($delta);
    
    /**
     * Appends a new section to the end of the list.
     *
     * @param \Drupal\layout_builder\Section $section
     *   The section to append.
     *
     * @return $this
     */
    public function appendSection(Section $section);
    
    /**
     * Inserts a new section at a given delta.
     *
     * If a section exists at the given index, the section at that position and
     * others after it are shifted backward.
     *
     * @param int $delta
     *   The delta of the section.
     * @param \Drupal\layout_builder\Section $section
     *   The section to insert.
     *
     * @return $this
     */
    public function insertSection($delta, Section $section);
    
    /**
     * Removes the section at the given delta.
     *
     * As sections are stored sequentially and numerically this will re-key every
     * subsequent section, shifting them forward.
     *
     * @param int $delta
     *   The delta of the section.
     *
     * @return $this
     */
    public function removeSection($delta);
    
    /**
     * Removes all of the sections.
     *
     * @param bool $set_blank
     *   (optional) The default implementation of section lists differentiates
     *   between a list that has never contained any sections and a list that has
     *   purposefully had all sections removed in order to remain blank. Passing
     *   TRUE will mirror ::removeSection() by tracking this as a blank list.
     *   Passing FALSE will reset the list as though it had never contained any
     *   sections at all. Defaults to FALSE.
     *
     * @return $this
     */
    public function removeAllSections($set_blank = FALSE);

}