@ckeditor/ckeditor5-engine
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The editing engine of CKEditor 5 – the best browser-based rich text editor.
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JavaScript
/**
* @license Copyright (c) 2003-2025, CKSource Holding sp. z o.o. All rights reserved.
* For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-licensing-options
*/
/**
* @module engine/model/documentfragment
*/
import { ModelTypeCheckable } from './typecheckable.js';
import { ModelElement } from './element.js';
import { ModelNodeList } from './nodelist.js';
import { ModelText } from './text.js';
import { ModelTextProxy } from './textproxy.js';
import { isIterable } from '@ckeditor/ckeditor5-utils';
// @if CK_DEBUG_ENGINE // const { stringifyMap } = require( '../dev-utils/utils' );
/**
* ModelDocumentFragment represents a part of model which does not have a common root but its top-level nodes
* can be seen as siblings. In other words, it is a detached part of model tree, without a root.
*
* ModelDocumentFragment has own {@link module:engine/model/markercollection~MarkerCollection}. Markers from this collection
* will be set to the {@link module:engine/model/model~Model#markers model markers} by a
* {@link module:engine/model/writer~ModelWriter#insert} function.
*/
export class ModelDocumentFragment extends ModelTypeCheckable {
/**
* ModelDocumentFragment static markers map. This is a list of names and {@link module:engine/model/range~ModelRange ranges}
* which will be set as Markers to {@link module:engine/model/model~Model#markers model markers collection}
* when ModelDocumentFragment will be inserted to the document.
*/
markers = new Map();
/**
* List of nodes contained inside the document fragment.
*/
_children = new ModelNodeList();
/**
* Creates an empty `ModelDocumentFragment`.
*
* **Note:** Constructor of this class shouldn't be used directly in the code.
* Use the {@link module:engine/model/writer~ModelWriter#createDocumentFragment} method instead.
*
* @internal
* @param children Nodes to be contained inside the `ModelDocumentFragment`.
*/
constructor(children) {
super();
if (children) {
this._insertChild(0, children);
}
}
/**
* Returns an iterator that iterates over all nodes contained inside this document fragment.
*/
[Symbol.iterator]() {
return this.getChildren();
}
/**
* Number of this document fragment's children.
*/
get childCount() {
return this._children.length;
}
/**
* Sum of {@link module:engine/model/node~ModelNode#offsetSize offset sizes} of all of this document fragment's children.
*/
get maxOffset() {
return this._children.maxOffset;
}
/**
* Is `true` if there are no nodes inside this document fragment, `false` otherwise.
*/
get isEmpty() {
return this.childCount === 0;
}
/**
* Artificial next sibling. Returns `null`. Added for compatibility reasons.
*/
get nextSibling() {
return null;
}
/**
* Artificial previous sibling. Returns `null`. Added for compatibility reasons.
*/
get previousSibling() {
return null;
}
/**
* Artificial root of `ModelDocumentFragment`. Returns itself. Added for compatibility reasons.
*/
get root() {
return this;
}
/**
* Artificial parent of `ModelDocumentFragment`. Returns `null`. Added for compatibility reasons.
*/
get parent() {
return null;
}
/**
* Artificial owner of `ModelDocumentFragment`. Returns `null`. Added for compatibility reasons.
*/
get document() {
return null;
}
/**
* Returns `false` as `ModelDocumentFragment` by definition is not attached to a document. Added for compatibility reasons.
*/
isAttached() {
return false;
}
/**
* Returns empty array. Added for compatibility reasons.
*/
getAncestors() {
return [];
}
/**
* Gets the child at the given index. Returns `null` if incorrect index was passed.
*
* @param index Index in this document fragment.
* @returns Child node.
*/
getChild(index) {
return this._children.getNode(index);
}
/**
* Gets the child at the given offset. Returns `null` if incorrect index was passed.
*
* @param offset Offset in this document fragment.
* @returns Child node.
*/
getChildAtOffset(offset) {
return this._children.getNodeAtOffset(offset);
}
/**
* Returns an iterator that iterates over all of this document fragment's children.
*/
getChildren() {
return this._children[Symbol.iterator]();
}
/**
* Returns an index of the given child node. Returns `null` if given node is not a child of this document fragment.
*
* @param node Child node to look for.
* @returns Child node's index.
*/
getChildIndex(node) {
return this._children.getNodeIndex(node);
}
/**
* Returns the starting offset of given child. Starting offset is equal to the sum of
* {@link module:engine/model/node~ModelNode#offsetSize offset sizes} of all node's siblings that are before it. Returns `null` if
* given node is not a child of this document fragment.
*
* @param node Child node to look for.
* @returns Child node's starting offset.
*/
getChildStartOffset(node) {
return this._children.getNodeStartOffset(node);
}
/**
* Returns path to a `ModelDocumentFragment`, which is an empty array. Added for compatibility reasons.
*/
getPath() {
return [];
}
/**
* Returns a descendant node by its path relative to this element.
*
* ```ts
* // <this>a<b>c</b></this>
* this.getNodeByPath( [ 0 ] ); // -> "a"
* this.getNodeByPath( [ 1 ] ); // -> <b>
* this.getNodeByPath( [ 1, 0 ] ); // -> "c"
* ```
*
* @param relativePath Path of the node to find, relative to this element.
*/
getNodeByPath(relativePath) {
// eslint-disable-next-line @typescript-eslint/no-this-alias, consistent-this
let node = this;
for (const offset of relativePath) {
node = node.getChildAtOffset(offset);
}
return node;
}
/**
* Converts offset "position" to index "position".
*
* Returns index of a node that occupies given offset. If given offset is too low, returns `0`. If given offset is
* too high, returns index after last child.
*
* ```ts
* const textNode = new Text( 'foo' );
* const pElement = new Element( 'p' );
* const docFrag = new ModelDocumentFragment( [ textNode, pElement ] );
* docFrag.offsetToIndex( -1 ); // Returns 0, because offset is too low.
* docFrag.offsetToIndex( 0 ); // Returns 0, because offset 0 is taken by `textNode` which is at index 0.
* docFrag.offsetToIndex( 1 ); // Returns 0, because `textNode` has `offsetSize` equal to 3, so it occupies offset 1 too.
* docFrag.offsetToIndex( 2 ); // Returns 0.
* docFrag.offsetToIndex( 3 ); // Returns 1.
* docFrag.offsetToIndex( 4 ); // Returns 2. There are no nodes at offset 4, so last available index is returned.
* ```
*
* @param offset Offset to look for.
* @returns Index of a node that occupies given offset.
*/
offsetToIndex(offset) {
return this._children.offsetToIndex(offset);
}
/**
* Converts `ModelDocumentFragment` instance to plain object and returns it.
* Takes care of converting all of this document fragment's children.
*
* @returns `ModelDocumentFragment` instance converted to plain object.
*/
toJSON() {
const json = [];
for (const node of this._children) {
json.push(node.toJSON());
}
return json;
}
/**
* Creates a `ModelDocumentFragment` instance from given plain object (i.e. parsed JSON string).
* Converts `ModelDocumentFragment` children to proper nodes.
*
* @param json Plain object to be converted to `ModelDocumentFragment`.
* @returns `ModelDocumentFragment` instance created using given plain object.
*/
static fromJSON(json) {
const children = [];
for (const child of json) {
if (child.name) {
// If child has name property, it is an Element.
children.push(ModelElement.fromJSON(child));
}
else {
// Otherwise, it is a Text node.
children.push(ModelText.fromJSON(child));
}
}
return new ModelDocumentFragment(children);
}
/**
* {@link #_insertChild Inserts} one or more nodes at the end of this document fragment.
*
* @internal
* @param items Items to be inserted.
*/
_appendChild(items) {
this._insertChild(this.childCount, items);
}
/**
* Inserts one or more nodes at the given index and sets {@link module:engine/model/node~ModelNode#parent parent} of these nodes
* to this document fragment.
*
* @internal
* @param index Index at which nodes should be inserted.
* @param items Items to be inserted.
*/
_insertChild(index, items) {
const nodes = normalize(items);
for (const node of nodes) {
// If node that is being added to this element is already inside another element, first remove it from the old parent.
if (node.parent !== null) {
node._remove();
}
node.parent = this;
}
this._children._insertNodes(index, nodes);
}
/**
* Removes one or more nodes starting at the given index
* and sets {@link module:engine/model/node~ModelNode#parent parent} of these nodes to `null`.
*
* @internal
* @param index Index of the first node to remove.
* @param howMany Number of nodes to remove.
* @returns Array containing removed nodes.
*/
_removeChildren(index, howMany = 1) {
const nodes = this._children._removeNodes(index, howMany);
for (const node of nodes) {
node.parent = null;
}
return nodes;
}
/**
* Removes children nodes provided as an array and sets
* the {@link module:engine/model/node~ModelNode#parent parent} of these nodes to `null`.
*
* These nodes do not need to be direct siblings.
*
* This method is faster than removing nodes one by one, as it recalculates offsets only once.
*
* @internal
* @param nodes Array of nodes.
*/
_removeChildrenArray(nodes) {
this._children._removeNodesArray(nodes);
for (const node of nodes) {
node.parent = null;
}
}
}
// The magic of type inference using `is` method is centralized in `TypeCheckable` class.
// Proper overload would interfere with that.
ModelDocumentFragment.prototype.is = function (type) {
return type === 'documentFragment' || type === 'model:documentFragment';
};
/**
* Converts strings to Text and non-iterables to arrays.
*/
function normalize(nodes) {
// Separate condition because string is iterable.
if (typeof nodes == 'string') {
return [new ModelText(nodes)];
}
if (!isIterable(nodes)) {
nodes = [nodes];
}
// Array.from to enable .map() on non-arrays.
return Array.from(nodes)
.map(node => {
if (typeof node == 'string') {
return new ModelText(node);
}
if (node instanceof ModelTextProxy) {
return new ModelText(node.data, node.getAttributes());
}
return node;
});
}