Undo Feature initial commit.

src/undocommand.js

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+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+'use strict';
+
+import Command from '../command/command.js';
+
+/**
+ * Undo command stores batches in itself and is able to and apply reverted versions of them on the document.
+ *
+ * undo.UndoCommand
+ */
+export default class UndoCommand extends Command {
+	/**
+	 * @see core.command.Command
+	 * @param {core.Editor} editor
+	 */
+	constructor( editor ) {
+		super( editor );
+
+		/**
+		 * Batches which are saved by the command. They can be reversed.
+		 *
+		 * @private
+		 * @member {Array.<core.treeModel.Batch>} core.command.UndoCommand#_batchStack
+		 */
+		this._batchStack = [];
+	}
+
+	/**
+	 * Stores a batch in the command. Stored batches can be then reverted.
+	 *
+	 * @param {core.teeModel.Batch} batch Batch to add.
+	 */
+	addBatch( batch ) {
+		this._batchStack.push( batch );
+	}
+
+	/**
+	 * Removes all batches from the stack.
+	 */
+	clearStack() {
+		this._batchStack = [];
+	}
+
+	/**
+	 * Checks whether this command should be enabled. Command is enabled when it has any batches in its stack.
+	 *
+	 * @private
+	 * @returns {Boolean}
+	 */
+	_checkEnabled() {
+		return this._batchStack.length > 0;
+	}
+
+	/**
+	 * Executes the command: reverts a {@link core.treeModel.Batch batch} added to the command's stack,
+	 * applies it on the document and removes the batch from the stack.
+	 *
+	 * Fires `undo` event with reverted batch as a parameter.
+	 *
+	 * @private
+	 * @param {Number} [batchIndex] If set, batch under the given index on the stack will be reverted and removed.
+	 * If not set, or invalid, the last added batch will be reverted and removed.
+	 */
+	_doExecute( batchIndex ) {
+		batchIndex = this._batchStack[ batchIndex ] ? batchIndex : this._batchStack.length - 1;
+
+		const undoBatch = this._batchStack.splice( batchIndex, 1 )[ 0 ];
+		const undoDeltas = undoBatch.deltas.slice();
+
+		undoDeltas.reverse();
+
+		for ( let undoDelta of undoDeltas ) {
+			const undoDeltaReversed = undoDelta.getReversed();
+			const updatedDeltas = this.editor.document.history.updateDelta( undoDeltaReversed );
+
+			for ( let delta of updatedDeltas ) {
+				for ( let operation of delta.operations ) {
+					this.editor.document.applyOperation( operation );
+				}
+			}
+		}
+
+		this.fire( 'undo', undoBatch );
+	}
+}

src/undofeature.js

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+/**
+ * @license Copyright (c) 2003-2016, CKSource - Frederico Knabben. All rights reserved.
+ * For licensing, see LICENSE.md.
+ */
+
+'use strict';
+
+import Feature from '../feature.js';
+import UndoCommand from './undocommand.js';
+
+/**
+ * Undo feature.
+ *
+ * Undo features brings in possibility to undo and re-do changes done in Tree Model by deltas through Batch API.
+ */
+export default class UndoFeature extends Feature {
+	constructor( editor ) {
+		super( editor );
+
+		/**
+		 * Undo command which manages undo {@link core.treeModel.Batch batches} stack (history).
+		 * Created and registered during {@link undo.UndoFeature#init feature initialization}.
+		 *
+		 * @private
+		 * @member {undo.UndoCommand} undo.UndoFeature#_undoCommand
+		 */
+		this._undoCommand = null;
+
+		/**
+		 * Undo command which manages redo {@link core.treeModel.Batch batches} stack (history).
+		 * Created and registered during {@link undo.UndoFeature#init feature initialization}.
+		 *
+		 * @private
+		 * @member {undo.UndoCommand} undo.UndoFeature#_redoCommand
+		 */
+		this._redoCommand = null;
+	}
+
+	/**
+	 * Initializes undo feature.
+	 */
+	init() {
+		// Create commands.
+		this._redoCommand = new UndoCommand( this.editor );
+		this._undoCommand = new UndoCommand( this.editor );
+
+		// Register command to the editor.
+		this.editor.commands.set( 'redo', this._redoCommand );
+		this.editor.commands.set( 'undo', this._undoCommand );
+
+		// Whenever new batch is created add it to undo history and clear redo history.
+		this.listenTo( this.editor.document, 'batch', ( evt, batch ) => {
+			this._undoCommand.addBatch( batch );
+			this._redoCommand.clearStack();
+		} );
+
+		// Whenever batch is reverted by undo command, add it to redo history.
+		this._undoCommand.listenTo( this._redoCommand, 'undo', ( evt, batch ) => {
+			this._undoCommand.addBatch( batch );
+		} );
+
+		// Whenever batch is reverted by redo command, add it to undo history.
+		this._redoCommand.listenTo( this._undoCommand, 'undo', ( evt, batch ) => {
+			this._redoCommand.addBatch( batch );
+		} );
+	}
+
+	destroy() {
+		this.stopListening();
+	}
+}