Add "block aware" transposeChars command

src/editor/block/transpose-chars.js

@@ -0,0 +1,30 @@
+import { EditorSelection, findClusterBreak} from "@codemirror/state";
+
+import { getNoteBlockFromPos } from "./block"
+
+/**
+Flip the characters before and after the cursor(s).
+*/
+export const transposeChars = ({ state, dispatch }) => {
+    if (state.readOnly)
+        return false;
+    let changes = state.changeByRange(range => {
+        // prevent transposing characters if we're at the start or end of a block, since it'll break the block syntax
+        const block = getNoteBlockFromPos(state, range.from)
+        if (range.from === block.content.from || range.from === block.content.to) {
+            return { range }
+        }
+
+        if (!range.empty || range.from == 0 || range.from == state.doc.length)
+            return { range };
+        let pos = range.from, line = state.doc.lineAt(pos);
+        let from = pos == line.from ? pos - 1 : findClusterBreak(line.text, pos - line.from, false) + line.from;
+        let to = pos == line.to ? pos + 1 : findClusterBreak(line.text, pos - line.from, true) + line.from;
+        return { changes: { from, to, insert: state.doc.slice(pos, to).append(state.doc.slice(from, pos)) },
+            range: EditorSelection.cursor(to) };
+    });
+    if (changes.changes.empty)
+        return false;
+    dispatch(state.update(changes, { scrollIntoView: true, userEvent: "move.character" }));
+    return true;
+};