src/model/node.js
/**
* @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/node
*/
import toMap from '@ckeditor/ckeditor5-utils/src/tomap';
import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';
import compareArrays from '@ckeditor/ckeditor5-utils/src/comparearrays';
// To check if component is loaded more than once.
import '@ckeditor/ckeditor5-utils/src/version';
/**
* Model node. Most basic structure of model tree.
*
* This is an abstract class that is a base for other classes representing different nodes in model.
*
* **Note:** If a node is detached from the model tree, you can manipulate it using it's API.
* However, it is **very important** that nodes already attached to model tree should be only changed through
* {@link module:engine/model/writer~Writer Writer API}.
*
* Changes done by `Node` methods, like {@link module:engine/model/element~Element#_insertChild _insertChild} or
* {@link module:engine/model/node~Node#_setAttribute _setAttribute}
* do not generate {@link module:engine/model/operation/operation~Operation operations}
* which are essential for correct editor work if you modify nodes in {@link module:engine/model/document~Document document} root.
*
* The flow of working on `Node` (and classes that inherits from it) is as such:
* 1. You can create a `Node` instance, modify it using it's API.
* 2. Add `Node` to the model using `Batch` API.
* 3. Change `Node` that was already added to the model using `Batch` API.
*
* Similarly, you cannot use `Batch` API on a node that has not been added to the model tree, with the exception
* of {@link module:engine/model/writer~Writer#insert inserting} that node to the model tree.
*
* Be aware that using {@link module:engine/model/writer~Writer#remove remove from Batch API} does not allow to use `Node` API because
* the information about `Node` is still kept in model document.
*
* In case of {@link module:engine/model/element~Element element node}, adding and removing children also counts as changing a node and
* follows same rules.
*/
export default class Node {
/**
* Creates a model node.
*
* This is an abstract class, so this constructor should not be used directly.
*
* @abstract
* @param {Object} [attrs] Node's attributes. See {@link module:utils/tomap~toMap} for a list of accepted values.
*/
constructor( attrs ) {
/**
* Parent of this node. It could be {@link module:engine/model/element~Element}
* or {@link module:engine/model/documentfragment~DocumentFragment}.
* Equals to `null` if the node has no parent.
*
* @readonly
* @member {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment|null}
*/
this.parent = null;
/**
* Attributes set on this node.
*
* @private
* @member {Map} module:engine/model/node~Node#_attrs
*/
this._attrs = toMap( attrs );
}
/**
* Index of this node in it's parent or `null` if the node has no parent.
*
* Accessing this property throws an error if this node's parent element does not contain it.
* This means that model tree got broken.
*
* @readonly
* @type {Number|null}
*/
get index() {
let pos;
if ( !this.parent ) {
return null;
}
if ( ( pos = this.parent.getChildIndex( this ) ) === null ) {
throw new CKEditorError( 'model-node-not-found-in-parent: The node\'s parent does not contain this node.', this );
}
return pos;
}
/**
* Offset at which this node starts in it's parent. It is equal to the sum of {@link #offsetSize offsetSize}
* of all it's previous siblings. Equals to `null` if node has no parent.
*
* Accessing this property throws an error if this node's parent element does not contain it.
* This means that model tree got broken.
*
* @readonly
* @type {Number|null}
*/
get startOffset() {
let pos;
if ( !this.parent ) {
return null;
}
if ( ( pos = this.parent.getChildStartOffset( this ) ) === null ) {
throw new CKEditorError( 'model-node-not-found-in-parent: The node\'s parent does not contain this node.', this );
}
return pos;
}
/**
* Offset size of this node. Represents how much "offset space" is occupied by the node in it's parent.
* It is important for {@link module:engine/model/position~Position position}. When node has `offsetSize` greater than `1`, position
* can be placed between that node start and end. `offsetSize` greater than `1` is for nodes that represents more
* than one entity, i.e. {@link module:engine/model/text~Text text node}.
*
* @readonly
* @type {Number}
*/
get offsetSize() {
return 1;
}
/**
* Offset at which this node ends in it's parent. It is equal to the sum of this node's
* {@link module:engine/model/node~Node#startOffset start offset} and {@link #offsetSize offset size}.
* Equals to `null` if the node has no parent.
*
* @readonly
* @type {Number|null}
*/
get endOffset() {
if ( !this.parent ) {
return null;
}
return this.startOffset + this.offsetSize;
}
/**
* Node's next sibling or `null` if the node is a last child of it's parent or if the node has no parent.
*
* @readonly
* @type {module:engine/model/node~Node|null}
*/
get nextSibling() {
const index = this.index;
return ( index !== null && this.parent.getChild( index + 1 ) ) || null;
}
/**
* Node's previous sibling or `null` if the node is a first child of it's parent or if the node has no parent.
*
* @readonly
* @type {module:engine/model/node~Node|null}
*/
get previousSibling() {
const index = this.index;
return ( index !== null && this.parent.getChild( index - 1 ) ) || null;
}
/**
* The top-most ancestor of the node. If node has no parent it is the root itself. If the node is a part
* of {@link module:engine/model/documentfragment~DocumentFragment}, it's `root` is equal to that `DocumentFragment`.
*
* @readonly
* @type {module:engine/model/node~Node|module:engine/model/documentfragment~DocumentFragment}
*/
get root() {
let root = this; // eslint-disable-line consistent-this
while ( root.parent ) {
root = root.parent;
}
return root;
}
/**
* Returns true if the node is in a tree rooted in the document (is a descendant of one of its roots).
*
* @returns {Boolean}
*/
isAttached() {
return this.root.is( 'rootElement' );
}
/**
* Gets path to the node. The path is an array containing starting offsets of consecutive ancestors of this node,
* beginning from {@link module:engine/model/node~Node#root root}, down to this node's starting offset. The path can be used to
* create {@link module:engine/model/position~Position Position} instance.
*
* const abc = new Text( 'abc' );
* const foo = new Text( 'foo' );
* const h1 = new Element( 'h1', null, new Text( 'header' ) );
* const p = new Element( 'p', null, [ abc, foo ] );
* const div = new Element( 'div', null, [ h1, p ] );
* foo.getPath(); // Returns [ 1, 3 ]. `foo` is in `p` which is in `div`. `p` starts at offset 1, while `foo` at 3.
* h1.getPath(); // Returns [ 0 ].
* div.getPath(); // Returns [].
*
* @returns {Array.<Number>} The path.
*/
getPath() {
const path = [];
let node = this; // eslint-disable-line consistent-this
while ( node.parent ) {
path.unshift( node.startOffset );
node = node.parent;
}
return path;
}
/**
* Returns ancestors array of this node.
*
* @param {Object} options Options object.
* @param {Boolean} [options.includeSelf=false] When set to `true` this node will be also included in parent's array.
* @param {Boolean} [options.parentFirst=false] When set to `true`, array will be sorted from node's parent to root element,
* otherwise root element will be the first item in the array.
* @returns {Array} Array with ancestors.
*/
getAncestors( options = { includeSelf: false, parentFirst: false } ) {
const ancestors = [];
let parent = options.includeSelf ? this : this.parent;
while ( parent ) {
ancestors[ options.parentFirst ? 'push' : 'unshift' ]( parent );
parent = parent.parent;
}
return ancestors;
}
/**
* Returns a {@link module:engine/model/element~Element} or {@link module:engine/model/documentfragment~DocumentFragment}
* which is a common ancestor of both nodes.
*
* @param {module:engine/model/node~Node} node The second node.
* @param {Object} options Options object.
* @param {Boolean} [options.includeSelf=false] When set to `true` both nodes will be considered "ancestors" too.
* Which means that if e.g. node A is inside B, then their common ancestor will be B.
* @returns {module:engine/model/element~Element|module:engine/model/documentfragment~DocumentFragment|null}
*/
getCommonAncestor( node, options = {} ) {
const ancestorsA = this.getAncestors( options );
const ancestorsB = node.getAncestors( options );
let i = 0;
while ( ancestorsA[ i ] == ancestorsB[ i ] && ancestorsA[ i ] ) {
i++;
}
return i === 0 ? null : ancestorsA[ i - 1 ];
}
/**
* Returns whether this node is before given node. `false` is returned if nodes are in different trees (for example,
* in different {@link module:engine/model/documentfragment~DocumentFragment}s).
*
* @param {module:engine/model/node~Node} node Node to compare with.
* @returns {Boolean}
*/
isBefore( node ) {
// Given node is not before this node if they are same.
if ( this == node ) {
return false;
}
// Return `false` if it is impossible to compare nodes.
if ( this.root !== node.root ) {
return false;
}
const thisPath = this.getPath();
const nodePath = node.getPath();
const result = compareArrays( thisPath, nodePath );
switch ( result ) {
case 'prefix':
return true;
case 'extension':
return false;
default:
return thisPath[ result ] < nodePath[ result ];
}
}
/**
* Returns whether this node is after given node. `false` is returned if nodes are in different trees (for example,
* in different {@link module:engine/model/documentfragment~DocumentFragment}s).
*
* @param {module:engine/model/node~Node} node Node to compare with.
* @returns {Boolean}
*/
isAfter( node ) {
// Given node is not before this node if they are same.
if ( this == node ) {
return false;
}
// Return `false` if it is impossible to compare nodes.
if ( this.root !== node.root ) {
return false;
}
// In other cases, just check if the `node` is before, and return the opposite.
return !this.isBefore( node );
}
/**
* Checks if the node has an attribute with given key.
*
* @param {String} key Key of attribute to check.
* @returns {Boolean} `true` if attribute with given key is set on node, `false` otherwise.
*/
hasAttribute( key ) {
return this._attrs.has( key );
}
/**
* Gets an attribute value for given key or `undefined` if that attribute is not set on node.
*
* @param {String} key Key of attribute to look for.
* @returns {*} Attribute value or `undefined`.
*/
getAttribute( key ) {
return this._attrs.get( key );
}
/**
* Returns iterator that iterates over this node's attributes.
*
* Attributes are returned as arrays containing two items. First one is attribute key and second is attribute value.
* This format is accepted by native `Map` object and also can be passed in `Node` constructor.
*
* @returns {Iterable.<*>}
*/
getAttributes() {
return this._attrs.entries();
}
/**
* Returns iterator that iterates over this node's attribute keys.
*
* @returns {Iterable.<String>}
*/
getAttributeKeys() {
return this._attrs.keys();
}
/**
* Converts `Node` to plain object and returns it.
*
* @returns {Object} `Node` converted to plain object.
*/
toJSON() {
const json = {};
// Serializes attributes to the object.
// attributes = { a: 'foo', b: 1, c: true }.
if ( this._attrs.size ) {
json.attributes = Array.from( this._attrs ).reduce( ( result, attr ) => {
result[ attr[ 0 ] ] = attr[ 1 ];
return result;
}, {} );
}
return json;
}
/**
* Checks whether this object is of the given type.
*
* This method is useful when processing model objects that are of unknown type. For example, a function
* may return a {@link module:engine/model/documentfragment~DocumentFragment} or a {@link module:engine/model/node~Node}
* that can be either a text node or an element. This method can be used to check what kind of object is returned.
*
* someObject.is( 'element' ); // -> true if this is an element
* someObject.is( 'node' ); // -> true if this is a node (a text node or an element)
* someObject.is( 'documentFragment' ); // -> true if this is a document fragment
*
* Since this method is also available on a range of view objects, you can prefix the type of the object with
* `model:` or `view:` to check, for example, if this is the model's or view's element:
*
* modelElement.is( 'model:element' ); // -> true
* modelElement.is( 'view:element' ); // -> false
*
* By using this method it is also possible to check a name of an element:
*
* imageElement.is( 'image' ); // -> true
* imageElement.is( 'element', 'image' ); // -> same as above
* imageElement.is( 'model:element', 'image' ); // -> same as above, but more precise
*
* The list of model objects which implement the `is()` method:
*
* * {@link module:engine/model/node~Node#is `Node#is()`}
* * {@link module:engine/model/text~Text#is `Text#is()`}
* * {@link module:engine/model/element~Element#is `Element#is()`}
* * {@link module:engine/model/rootelement~RootElement#is `RootElement#is()`}
* * {@link module:engine/model/position~Position#is `Position#is()`}
* * {@link module:engine/model/liveposition~LivePosition#is `LivePosition#is()`}
* * {@link module:engine/model/range~Range#is `Range#is()`}
* * {@link module:engine/model/liverange~LiveRange#is `LiveRange#is()`}
* * {@link module:engine/model/documentfragment~DocumentFragment#is `DocumentFragment#is()`}
* * {@link module:engine/model/selection~Selection#is `Selection#is()`}
* * {@link module:engine/model/documentselection~DocumentSelection#is `DocumentSelection#is()`}
* * {@link module:engine/model/markercollection~Marker#is `Marker#is()`}
* * {@link module:engine/model/textproxy~TextProxy#is `TextProxy#is()`}
*
* @method #is
* @param {String} type
* @returns {Boolean}
*/
is( type ) {
return type === 'node' || type === 'model:node';
}
/**
* Creates a copy of this node, that is a node with exactly same attributes, and returns it.
*
* @protected
* @returns {module:engine/model/node~Node} Node with same attributes as this node.
*/
_clone() {
return new Node( this._attrs );
}
/**
* Removes this node from it's parent.
*
* @see module:engine/model/writer~Writer#remove
* @protected
*/
_remove() {
this.parent._removeChildren( this.index );
}
/**
* Sets attribute on the node. If attribute with the same key already is set, it's value is overwritten.
*
* @see module:engine/model/writer~Writer#setAttribute
* @protected
* @param {String} key Key of attribute to set.
* @param {*} value Attribute value.
*/
_setAttribute( key, value ) {
this._attrs.set( key, value );
}
/**
* Removes all attributes from the node and sets given attributes.
*
* @see module:engine/model/writer~Writer#setAttributes
* @protected
* @param {Object} [attrs] Attributes to set. See {@link module:utils/tomap~toMap} for a list of accepted values.
*/
_setAttributesTo( attrs ) {
this._attrs = toMap( attrs );
}
/**
* Removes an attribute with given key from the node.
*
* @see module:engine/model/writer~Writer#removeAttribute
* @protected
* @param {String} key Key of attribute to remove.
* @returns {Boolean} `true` if the attribute was set on the element, `false` otherwise.
*/
_removeAttribute( key ) {
return this._attrs.delete( key );
}
/**
* Removes all attributes from the node.
*
* @see module:engine/model/writer~Writer#clearAttributes
* @protected
*/
_clearAttributes() {
this._attrs.clear();
}
}