ckeditor5-image-upload-base64
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The development environment of CKEditor 5 – the best browser-based rich text editor.
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JavaScript
/**
* @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/history
*/
/**
* `History` keeps the track of all the operations applied to the {@link module:engine/model/document~Document document}.
*/
export default class History {
/**
* Creates an empty History instance.
*/
constructor() {
/**
* Operations added to the history.
*
* @protected
* @member {Array.<module:engine/model/operation/operation~Operation>} module:engine/model/history~History#_operations
*/
this._operations = [];
/**
* Holds an information which {@link module:engine/model/operation/operation~Operation operation} undoes which
* {@link module:engine/model/operation/operation~Operation operation}.
*
* Keys of the map are "undoing operations", that is operations that undone some other operations. For each key, the
* value is an operation that has been undone by the "undoing operation".
*
* @private
* @member {Map} module:engine/model/history~History#_undoPairs
*/
this._undoPairs = new Map();
/**
* Holds all undone operations.
*
* @private
* @member {Set.<module:engine/model/operation/operation~Operation>} module:engine/model/history~History#_undoneOperations
*/
this._undoneOperations = new Set();
}
/**
* Adds an operation to the history.
*
* @param {module:engine/model/operation/operation~Operation} operation Operation to add.
*/
addOperation( operation ) {
if ( this._operations.includes( operation ) ) {
return;
}
this._operations.push( operation );
}
/**
* Returns operations added to the history.
*
* @param {Number} [from=0] Base version from which operations should be returned (inclusive). Defaults to `0`, which means
* that operations from the first one will be returned.
* @param {Number} [to=Number.POSITIVE_INFINITY] Base version up to which operations should be returned (exclusive).
* Defaults to `Number.POSITIVE_INFINITY` which means that operations up to the last one will be returned.
* @returns {Iterable.<module:engine/model/operation/operation~Operation>} Operations added to the history.
*/
getOperations( from = 0, to = Number.POSITIVE_INFINITY ) {
if ( from < 0 ) {
return [];
}
return this._operations.slice( from, to );
}
/**
* Returns operation from the history that bases on given `baseVersion`.
*
* @param {Number} baseVersion Base version of the operation to get.
* @returns {module:engine/model/operation/operation~Operation|null} Operation with given base version or `null` if
* there is no such operation in history.
*/
getOperation( baseVersion ) {
return this._operations[ baseVersion ];
}
/**
* Marks in history that one operation is an operation that is undoing the other operation. By marking operation this way,
* history is keeping more context information about operations, which helps in operational transformation.
*
* @param {module:engine/model/operation/operation~Operation} undoneOperation Operation which is undone by `undoingOperation`.
* @param {module:engine/model/operation/operation~Operation} undoingOperation Operation which undoes `undoneOperation`.
*/
setOperationAsUndone( undoneOperation, undoingOperation ) {
this._undoPairs.set( undoingOperation, undoneOperation );
this._undoneOperations.add( undoneOperation );
}
/**
* Checks whether given `operation` is undoing any other operation.
*
* @param {module:engine/model/operation/operation~Operation} operation Operation to check.
* @returns {Boolean} `true` if given `operation` is undoing any other operation, `false` otherwise.
*/
isUndoingOperation( operation ) {
return this._undoPairs.has( operation );
}
/**
* Checks whether given `operation` has been undone by any other operation.
*
* @param {module:engine/model/operation/operation~Operation} operation Operation to check.
* @returns {Boolean} `true` if given `operation` has been undone any other operation, `false` otherwise.
*/
isUndoneOperation( operation ) {
return this._undoneOperations.has( operation );
}
/**
* For given `undoingOperation`, returns the operation which has been undone by it.
*
* @param {module:engine/model/operation/operation~Operation} undoingOperation
* @returns {module:engine/model/operation/operation~Operation|undefined} Operation that has been undone by given
* `undoingOperation` or `undefined` if given `undoingOperation` is not undoing any other operation.
*/
getUndoneOperation( undoingOperation ) {
return this._undoPairs.get( undoingOperation );
}
}