@ckeditor/ckeditor5-undo/src/undocommand.js

Undo feature for CKEditor 5.

/**
 * @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 undo/undocommand
 */
import BaseCommand from './basecommand.js';
/**
 * The undo command stores {@link module:engine/model/batch~Batch batches} applied to the
 * {@link module:engine/model/document~Document document} and is able to undo a batch by reversing it and transforming by
 * batches from {@link module:engine/model/document~Document#history history} that happened after the reversed batch.
 *
 * The undo command also takes care of restoring the {@link module:engine/model/document~Document#selection document selection}.
 */
export default class UndoCommand extends BaseCommand {
    /**
     * Executes the command. This method reverts a {@link module:engine/model/batch~Batch batch} added to the command's stack, transforms
     * and applies the reverted version on the {@link module:engine/model/document~Document document} and removes the batch from the stack.
     * Then, it restores the {@link module:engine/model/document~Document#selection document selection}.
     *
     * @fires execute
     * @fires revert
     * @param batch A batch that should be undone. If not set, the last added batch will be undone.
     */
    execute(batch = null) {
        // If batch is not given, set `batchIndex` to the last index in command stack.
        const batchIndex = batch ? this._stack.findIndex(a => a.batch == batch) : this._stack.length - 1;
        const item = this._stack.splice(batchIndex, 1)[0];
        const undoingBatch = this.editor.model.createBatch({ isUndo: true });
        // All changes have to be done in one `enqueueChange` callback so other listeners will not
        // step between consecutive operations, or won't do changes to the document before selection is properly restored.
        this.editor.model.enqueueChange(undoingBatch, () => {
            this._undo(item.batch, undoingBatch);
            const operations = this.editor.model.document.history.getOperations(item.batch.baseVersion);
            this._restoreSelection(item.selection.ranges, item.selection.isBackward, operations);
        });
        // Firing `revert` event after the change block to make sure that it includes all changes from post-fixers
        // and make sure that the selection is "stabilized" (the selection range is saved after undo is executed and then
        // restored on redo, so it is important that the selection range is saved after post-fixers are done).
        this.fire('revert', item.batch, undoingBatch);
        this.refresh();
    }
}