Add undo point for automatic list creation

If you do `*` then space or `1. ` then space at the beginning of a line,
we automatically create a list. Now you can use undo to undo just the
automatic list creation, reverting to the plain text you typed.

source/Editor.ts

@@ -839,33 +839,39 @@ class Squire {
      * Leaves bookmark.
      */
     _recordUndoState(range: Range, replace?: boolean): Squire {
-        // Don't record if we're already in an undo state
-        if (!this._isInUndoState || replace) {
+        const isInUndoState = this._isInUndoState;
+        if (!isInUndoState || replace) {
             // Advance pointer to new position
-            let undoIndex = this._undoIndex;
+            let undoIndex = this._undoIndex + 1;
             const undoStack = this._undoStack;
             const undoConfig = this._config.undo;
             const undoThreshold = undoConfig.documentSizeThreshold;
             const undoLimit = undoConfig.undoLimit;
 
-            if (!replace) {
-                undoIndex += 1;
-            }
-
             // Truncate stack if longer (i.e. if has been previously undone)
             if (undoIndex < this._undoStackLength) {
                 undoStack.length = this._undoStackLength = undoIndex;
             }
 
-            // Get data
+            // Add bookmark
             if (range) {
                 this._saveRangeToBookmark(range);
             }
+
+            // Don't record if we're already in an undo state
+            if (isInUndoState) {
+                return this;
+            }
+
+            // Get data
             const html = this._getRawHTML();
 
             // If this document is above the configured size threshold,
             // limit the number of saved undo states.
             // Threshold is in bytes, JS uses 2 bytes per character
+            if (replace) {
+                undoIndex -= 1;
+            }
             if (undoThreshold > -1 && html.length * 2 > undoThreshold) {
                 if (undoLimit > -1 && undoIndex > undoLimit) {
                     undoStack.splice(0, undoIndex - undoLimit);

source/keyboard/Space.ts

@@ -1,4 +1,4 @@
-import { getLength } from '../node/Node';
+import { detach, getLength } from '../node/Node';
 import { moveRangeBoundariesDownTree } from '../range/Boundaries';
 import { deleteContentsOfRange } from '../range/InsertDelete';
 
@@ -9,7 +9,7 @@ import {
     rangeDoesEndAtBlockBoundary,
 } from '../range/Block';
 import { SHOW_TEXT, TreeIterator } from '../node/TreeIterator';
-import { ZWS, cantFocusEmptyTextNodes } from '../Constants';
+import { ZWS } from '../Constants';
 
 // ---
 
@@ -31,10 +31,13 @@ const Space = (self: Squire, event: KeyboardEvent, range: Range): void => {
             const text = block.textContent?.trimEnd().replace(ZWS, '');
             if (text === '*' || text === '1.') {
                 event.preventDefault();
+                self.insertPlainText(' ', false);
+                self._docWasChanged();
+                self.saveUndoState(range);
                 const walker = new TreeIterator<Text>(block, SHOW_TEXT);
                 let textNode: Text | null;
                 while ((textNode = walker.nextNode())) {
-                    textNode.data = cantFocusEmptyTextNodes ? ZWS : '';
+                    detach(textNode);
                 }
                 if (text === '*') {
                     self.makeUnorderedList();