/** * @license Copyright (c) 2003-2017, CKSource - Frederico Knabben. All rights reserved. * For licensing, see LICENSE.md. */ /** * @module typing/changebuffer */ import count from '@ckeditor/ckeditor5-utils/src/count'; /** * Change buffer allows to group atomic changes (like characters that have been typed) into * {@link module:engine/model/batch~Batch batches}. * * Batches represent single undo steps, hence changes added to one single batch are undone together. * * The buffer has a configurable limit of atomic changes that it can accommodate. After the limit was * exceeded (see {@link ~ChangeBuffer#input}), a new batch is created in {@link ~ChangeBuffer#batch}. * * To use the change buffer you need to let it know about the number of changes that were added to the batch: * * const buffer = new ChangeBuffer( document, LIMIT ); * * // Later on in your feature: * buffer.batch.insert( pos, insertedCharacters ); * buffer.input( insertedCharacters.length ); * */ export default class ChangeBuffer { /** * Creates a new instance of the change buffer. * * @param {module:engine/model/document~Document} document * @param {Number} [limit=20] The maximum number of atomic changes which can be contained in one batch. */ constructor( doc, limit = 20 ) { /** * The document instance. * * @readonly * @member {module:engine/model/document~Document} #document */ this.document = doc; /** * The number of atomic changes in the buffer. Once it exceeds the {@link #limit}, * the {@link #batch batch} is set to a new one. * * @readonly * @member {Number} #size */ this.size = 0; /** * The maximum number of atomic changes which can be contained in one batch. * * @readonly * @member {Number} #limit */ this.limit = limit; /** * Whether the buffer is locked. The locked buffer cannot be reset unless it gets unlocked. * * @readonly * @member {Boolean} #isLocked */ this.isLocked = false; this._changeCallback = ( evt, type, changes, batch ) => { this._onBatch( batch ); }; this._selectionChangeCallback = () => { this._reset(); }; doc.on( 'change', this._changeCallback ); doc.selection.on( 'change:range', this._selectionChangeCallback ); doc.selection.on( 'change:attribute', this._selectionChangeCallback ); /** * The current batch instance. * * @private * @member #_batch */ /** * The callback to document the change event which later needs to be removed. * * @private * @member #_changeCallback */ /** * The callback to document selection change:attribute and change:range events which resets the buffer. * * @private * @member #_selectionChangeCallback */ } /** * The current batch to which a feature should add its deltas. Once the {@link #size} * is reached or exceeds the {@link #limit}, the batch is set to a new instance and the size is reset. * * @type {module:engine/model/batch~Batch} */ get batch() { if ( !this._batch ) { this._batch = this.document.batch(); } return this._batch; } /** * The input number of changes into the buffer. Once the {@link #size} is * reached or exceeds the {@link #limit}, the batch is set to a new instance and the size is reset. * * @param {Number} changeCount The number of atomic changes to input. */ input( changeCount ) { this.size += changeCount; if ( this.size >= this.limit ) { this._reset( true ); } } /** * Locks the buffer. */ lock() { this.isLocked = true; } /** * Unlocks the buffer. */ unlock() { this.isLocked = false; } /** * Destroys the buffer. */ destroy() { this.document.off( 'change', this._changeCallback ); this.document.selection.off( 'change:range', this._selectionChangeCallback ); this.document.selection.off( 'change:attribute', this._selectionChangeCallback ); } /** * The method to be called in order to notify the buffer about batches which appeared in the document. * The method will check whether it is a new batch and in that case the buffer will be flushed. * * The reason why the buffer needs to be flushed whenever a new batch appears is that the changes added afterwards * should be added to a new batch. For instance, when the user types, then inserts an image, and then types again, * the characters typed after inserting the image should be added to a different batch than the characters typed before. * * @private * @param {module:engine/model/batch~Batch} batch The batch which appears in the document. */ _onBatch( batch ) { // One operation means a newly created batch. if ( batch.type != 'transparent' && batch !== this._batch && count( batch.getOperations() ) <= 1 ) { this._reset( true ); } } /** * Resets the change buffer. * * @private * @param {Boolean} [ignoreLock] Whether internal lock {@link #isLocked} should be ignored. */ _reset( ignoreLock ) { if ( !this.isLocked || ignoreLock ) { this._batch = null; this.size = 0; } } }