ckeditor/ckeditor5-engine

/**
 * @license Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
 * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
 */

/**
 * @module engine/model/rootelement
 */

import Element from './element';

/**
 * Type of {@link module:engine/model/element~Element} that is a root of a model tree.
 * @extends module:engine/model/element~Element
 */
export default class RootElement extends Element {
    /**
     * Creates root element.
     *
     * @param {module:engine/model/document~Document} document Document that is an owner of this root.
     * @param {String} name Node name.
     * @param {String} [rootName='main'] Unique root name used to identify this root
     * element by {@link module:engine/model/document~Document}.
     */
    constructor( document, name, rootName = 'main' ) {
        super( name );

        /**
         * Document that is an owner of this root.
         *
         * @private
         * @member {module:engine/model/document~Document}
         */
        this._document = document;

        /**
         * Unique root name used to identify this root element by {@link module:engine/model/document~Document}.
         *
         * @readonly
         * @member {String}
         */
        this.rootName = rootName;
    }

    /**
     * {@link module:engine/model/document~Document Document} that owns this root element.
     *
     * @readonly
     * @type {module:engine/model/document~Document|null}
     */
    get document() {
        return this._document;
    }

    /**
     * Checks whether this object is of the given.
     *
     *        rootElement.is( 'rootElement' ); // -> true
     *        rootElement.is( 'element' ); // -> true
     *        rootElement.is( 'node' ); // -> true
     *        rootElement.is( 'model:rootElement' ); // -> true
     *        rootElement.is( 'model:element' ); // -> true
     *        rootElement.is( 'model:node' ); // -> true
     *
     *        rootElement.is( 'view:element' ); // -> false
     *        rootElement.is( 'documentFragment' ); // -> false
     *
     * Assuming that the object being checked is an element, you can also check its
     * {@link module:engine/model/element~Element#name name}:
     *
     *        rootElement.is( '$root' ); // -> true if this is a $root element
     *        rootElement.is( 'rootElement', '$root' ); // -> same as above
     *        text.is( '$root' ); -> false
     *
     * {@link module:engine/model/node~Node#is Check the entire list of model objects} which implement the `is()` method.
     *
     * @param {String} type Type to check when `name` parameter is present.
     * Otherwise, it acts like the `name` parameter.
     * @param {String} [name] Element name.
     * @returns {Boolean}
     */
    is( type, name ) {
        if ( !name ) {
            return type === 'rootElement' || type === 'model:rootElement' ||
                // From super.is(). This is highly utilised method and cannot call super. See ckeditor/ckeditor5#6529.
                type === 'element' || type === 'model:element' ||
                type === this.name || type === 'model:' + this.name ||
                type === 'node' || type === 'model:node';
        }

        return name === this.name && (
            type === 'rootElement' || type === 'model:rootElement' ||
            // From super.is(). This is highly utilised method and cannot call super. See ckeditor/ckeditor5#6529.
            type === 'element' || type === 'model:element'
        );
    }

    /**
     * Converts `RootElement` instance to `String` containing it's name.
     *
     * @returns {String} `RootElement` instance converted to `String`.
     */
    toJSON() {
        return this.rootName;
    }

    // @if CK_DEBUG_ENGINE // toString() {
    // @if CK_DEBUG_ENGINE //     return this.rootName;
    // @if CK_DEBUG_ENGINE // }

    // @if CK_DEBUG_ENGINE // log() {
    // @if CK_DEBUG_ENGINE //     console.log( 'ModelRootElement: ' + this );
    // @if CK_DEBUG_ENGINE // }
}