@ckeditor/ckeditor5-list/src/list/indentcommand.js

Ordered and unordered lists feature to CKEditor 5.

/**
 * @license Copyright (c) 2003-2023, CKSource Holding sp. z o.o. All rights reserved.
 * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
 */
import { Command } from 'ckeditor5/src/core';
import { first } from 'ckeditor5/src/utils';
/**
 * The list indent command. It is used by the {@link module:list/list~List list feature}.
 */
export default class IndentCommand extends Command {
    /**
     * Creates an instance of the command.
     *
     * @param editor The editor instance.
     * @param indentDirection The direction of indent. If it is equal to `backward`, the command will outdent a list item.
     */
    constructor(editor, indentDirection) {
        super(editor);
        this._indentBy = indentDirection == 'forward' ? 1 : -1;
    }
    /**
     * @inheritDoc
     */
    refresh() {
        this.isEnabled = this._checkEnabled();
    }
    /**
     * Indents or outdents (depending on the {@link #constructor}'s `indentDirection` parameter) selected list items.
     *
     * @fires execute
     */
    execute() {
        const model = this.editor.model;
        const doc = model.document;
        let itemsToChange = Array.from(doc.selection.getSelectedBlocks());
        model.change(writer => {
            const lastItem = itemsToChange[itemsToChange.length - 1];
            // Indenting a list item should also indent all the items that are already sub-items of indented item.
            let next = lastItem.nextSibling;
            // Check all items after last indented item, as long as their indent is bigger than indent of that item.
            while (next && next.name == 'listItem' &&
                next.getAttribute('listIndent') > lastItem.getAttribute('listIndent')) {
                itemsToChange.push(next);
                next = next.nextSibling;
            }
            // We need to be sure to keep model in correct state after each small change, because converters
            // bases on that state and assumes that model is correct.
            // Because of that, if the command outdents items, we will outdent them starting from the last item, as
            // it is safer.
            if (this._indentBy < 0) {
                itemsToChange = itemsToChange.reverse();
            }
            for (const item of itemsToChange) {
                const indent = item.getAttribute('listIndent') + this._indentBy;
                // If indent is lower than 0, it means that the item got outdented when it was not indented.
                // This means that we need to convert that list item to paragraph.
                if (indent < 0) {
                    // To keep the model as correct as possible, first rename listItem, then remove attributes,
                    // as listItem without attributes is very incorrect and will cause problems in converters.
                    // No need to remove attributes, will be removed by post fixer.
                    writer.rename(item, 'paragraph');
                }
                // If indent is >= 0, change the attribute value.
                else {
                    writer.setAttribute('listIndent', indent, item);
                }
            }
            // It allows to execute an action after executing the `~IndentCommand#execute` method, for example adjusting
            // attributes of changed list items.
            this.fire('_executeCleanup', itemsToChange);
        });
    }
    /**
     * Checks whether the command can be enabled in the current context.
     *
     * @returns Whether the command should be enabled.
     */
    _checkEnabled() {
        // Check whether any of position's ancestor is a list item.
        const listItem = first(this.editor.model.document.selection.getSelectedBlocks());
        // If selection is not in a list item, the command is disabled.
        if (!listItem || !listItem.is('element', 'listItem')) {
            return false;
        }
        if (this._indentBy > 0) {
            // Cannot indent first item in it's list. Check if before `listItem` is a list item that is in same list.
            // To be in the same list, the item has to have same attributes and cannot be "split" by an item with lower indent.
            const indent = listItem.getAttribute('listIndent');
            const type = listItem.getAttribute('listType');
            let prev = listItem.previousSibling;
            while (prev && prev.is('element', 'listItem') && prev.getAttribute('listIndent') >= indent) {
                if (prev.getAttribute('listIndent') == indent) {
                    // The item is on the same level.
                    // If it has same type, it means that we found a preceding sibling from the same list.
                    // If it does not have same type, it means that `listItem` is on different list (this can happen only
                    // on top level lists, though).
                    return prev.getAttribute('listType') == type;
                }
                prev = prev.previousSibling;
            }
            // Could not find similar list item, this means that `listItem` is first in its list.
            return false;
        }
        // If we are outdenting it is enough to be in list item. Every list item can always be outdented.
        return true;
    }
}