feat: support selection counters

example/lib/pages/editor.dart

@@ -44,6 +44,9 @@ class _EditorState extends State<Editor> {
   int wordCount = 0;
   int charCount = 0;
 
+  int selectedWordCount = 0;
+  int selectedCharCount = 0;
+
   void registerWordCounter() {
     wordCountService?.removeListener(onWordCountUpdate);
     wordCountService?.dispose();
@@ -58,8 +61,10 @@ class _EditorState extends State<Editor> {
 
   void onWordCountUpdate() {
     setState(() {
-      wordCount = wordCountService!.wordCount;
-      charCount = wordCountService!.charCount;
+      wordCount = wordCountService!.documentCounters.wordCount;
+      charCount = wordCountService!.documentCounters.charCount;
+      selectedWordCount = wordCountService!.selectionCounters.wordCount;
+      selectedCharCount = wordCountService!.selectionCounters.charCount;
     });
   }
 
@@ -132,9 +137,18 @@ class _EditorState extends State<Editor> {
                     : Radius.zero,
               ),
             ),
-            child: Text(
-              'Word Count: $wordCount  |  Character Count: $charCount',
-              style: const TextStyle(fontSize: 11),
+            child: Column(
+              children: [
+                Text(
+                  'Word Count: $wordCount  |  Character Count: $charCount',
+                  style: const TextStyle(fontSize: 11),
+                ),
+                if (!(editorState?.selection?.isCollapsed ?? true))
+                  Text(
+                    '(In-selection) Word Count: $selectedWordCount  |  Character Count: $selectedCharCount',
+                    style: const TextStyle(fontSize: 11),
+                  ),
+              ],
             ),
           ),
         ),

lib/src/plugins/word_count/word_counter_service.dart

@@ -4,8 +4,36 @@
 
 import 'package:appflowy_editor/appflowy_editor.dart';
 
+const _emptyCounters = Counters();
 final _wordRegex = RegExp(r"\w+(\'\w+)?");
 
+/// Used by the [WordCountService] to contain
+/// count statistics in eg. a [Document] or in
+/// the current [Selection].
+///
+class Counters {
+  const Counters({
+    int wordCount = 0,
+    int charCount = 0,
+  })  : _wordCount = wordCount,
+        _charCount = charCount;
+
+  final int _wordCount;
+  int get wordCount => _wordCount;
+
+  final int _charCount;
+  int get charCount => _charCount;
+
+  @override
+  bool operator ==(other) =>
+      other is Counters &&
+      other.wordCount == wordCount &&
+      other.charCount == charCount;
+
+  @override
+  int get hashCode => Object.hash(wordCount, charCount);
+}
+
 /// A Word Counter service that runs based on the
 /// changes and updates to an [EditorState].
 ///
@@ -24,17 +52,15 @@
 
   final EditorState editorState;
 
-  int _wordCount = 0;
-
-  /// Number of words in the [Document].
+  /// Number of words and characters in the [Document].
   ///
-  int get wordCount => _wordCount;
-
-  int _charCount = 0;
+  Counters get documentCounters => _documentCounters;
+  Counters _documentCounters = const Counters();
 
-  /// Number of characters with spaces in the [Document].
+  /// Number of words and characters in the [Selection].
   ///
-  int get charCount => _charCount;
+  Counters get selectionCounters => _selectionCounters;
+  Counters _selectionCounters = const Counters();
 
   /// Signifies whether the service is currently running
   /// or not. The service can be stopped/started as needed
@@ -53,15 +79,19 @@
     }
 
     isRunning = true;
+    _documentCounters = _countersFromNode(editorState.document.root);
+    if (editorState.selection?.isCollapsed ?? false) {
+      _recountOnSelectionUpdate();
+    }
 
-    final counters = _countersFromNode(editorState.document.root);
-    _wordCount = counters.$1;
-    _charCount = counters.$2;
-
-    notifyListeners();
+    if (documentCounters != _emptyCounters ||
+        selectionCounters != _emptyCounters) {
+      notifyListeners();
+    }
 
     _streamSubscription =
         editorState.transactionStream.listen(_recountOnTransactionUpdate);
+    editorState.selectionNotifier.addListener(_recountOnSelectionUpdate);
   }
 
   /// Stops the Word Counter and resets the counts.
@@ -72,19 +102,53 @@
     }
 
     _streamSubscription?.cancel();
-    _wordCount = 0;
-    _charCount = 0;
+    _documentCounters = const Counters();
+    _selectionCounters = const Counters();
     isRunning = false;
 
     notifyListeners();
   }
 
   @override
   void dispose() {
+    editorState.selectionNotifier.removeListener(_recountOnSelectionUpdate);
     _streamSubscription?.cancel();
     super.dispose();
   }
 
+  void _recountOnSelectionUpdate() {
+    // If collapsed or null, reset count
+    if (editorState.selection?.isCollapsed ?? true) {
+      if (_selectionCounters == _emptyCounters) {
+        return;
+      }
+
+      _selectionCounters = const Counters();
+
+      return notifyListeners();
+    }
+
+    int wordCount = 0;
+    int charCount = 0;
+
+    final nodes = editorState.getSelectedNodes();
+    for (final node in nodes) {
+      final counters = _countersFromNode(node);
+      wordCount += counters.wordCount;
+      charCount += counters.charCount;
+    }
+
+    final newCounters = Counters(
+      wordCount: wordCount,
+      charCount: charCount,
+    );
+
+    if (newCounters != selectionCounters) {
+      _selectionCounters = newCounters;
+      notifyListeners();
+    }
+  }
+
   void _recountOnTransactionUpdate(
     (TransactionTime time, Transaction t) event,
   ) {
@@ -95,15 +159,16 @@
     final counters = _countersFromNode(editorState.document.root);
 
     // If there is no update, no need to notify listeners
-    if (counters.$1 != wordCount || counters.$2 != charCount) {
-      _wordCount = counters.$1;
-      _charCount = counters.$2;
-
-      notifyListeners();
+    if (counters.wordCount != documentCounters.wordCount ||
+        counters.charCount != documentCounters.charCount) {
+      if (counters != documentCounters) {
+        _documentCounters = counters;
+        notifyListeners();
+      }
     }
   }
 
-  (int, int) _countersFromNode(Node node) {
+  Counters _countersFromNode(Node node) {
     int wCount = 0;
     int cCount = 0;
 
@@ -112,12 +177,12 @@
     cCount += plain.runes.length;
 
     for (final child in node.children) {
-      final values = _countersFromNode(child);
-      wCount += values.$1;
-      cCount += values.$2;
+      final counters = _countersFromNode(child);
+      wCount += counters.wordCount;
+      cCount += counters.charCount;
     }
 
-    return (wCount, cCount);
+    return Counters(wordCount: wCount, charCount: cCount);
   }
 
   int _wordsInString(String delta) => _wordRegex.allMatches(delta).length;

test/plugins/word_count/word_counter_test.dart

@@ -4,13 +4,13 @@ import 'package:flutter_test/flutter_test.dart';
 import '../../new/infra/testable_editor.dart';
 
 void main() async {
-  late final WordCountService service;
+  late WordCountService service;
 
   setUpAll(() {
     TestWidgetsFlutterBinding.ensureInitialized();
   });
 
-  tearDown(() {
+  tearDownAll(() {
     service.dispose();
   });
 
@@ -24,15 +24,15 @@ void main() async {
 
         service = WordCountService(editorState: editor.editorState)..register();
 
-        expect(service.wordCount, 3 * 3); // 9 Words
-        expect(service.charCount, text.length * 3);
+        expect(service.documentCounters.wordCount, 3 * 3); // 9 Words
+        expect(service.documentCounters.charCount, text.length * 3);
 
         int wordCount = 0;
         int charCount = 0;
 
         void setCounters() {
-          wordCount = service.wordCount;
-          charCount = service.charCount;
+          wordCount = service.documentCounters.wordCount;
+          charCount = service.documentCounters.charCount;
         }
 
         service.addListener(setCounters);
@@ -48,15 +48,61 @@ void main() async {
 
         await tester.pumpAndSettle();
 
-        expect(service.wordCount, 3 * 4);
-        expect(service.charCount, text.length * 4);
+        expect(service.documentCounters.wordCount, 3 * 4);
+        expect(service.documentCounters.charCount, text.length * 4);
         expect(wordCount, 3 * 4);
         expect(charCount, text.length * 4);
 
         service.stop();
 
-        expect(service.wordCount, 0);
-        expect(service.charCount, 0);
+        expect(service.documentCounters.wordCount, 0);
+        expect(service.documentCounters.charCount, 0);
+        expect(wordCount, 0);
+        expect(charCount, 0);
+
+        service.removeListener(setCounters);
+      },
+    );
+
+    testWidgets(
+      'Selection Word and Character count updates',
+      (tester) async {
+        const text = 'Welcome to Appflowy!';
+        final editor = tester.editor..addParagraphs(3, initialText: text);
+        await editor.startTesting();
+
+        service = WordCountService(editorState: editor.editorState)..register();
+
+        expect(service.selectionCounters.wordCount, 0);
+        expect(service.selectionCounters.charCount, 0);
+
+        int wordCount = 0;
+        int charCount = 0;
+
+        void setCounters() {
+          wordCount = service.selectionCounters.wordCount;
+          charCount = service.selectionCounters.charCount;
+        }
+
+        service.addListener(setCounters);
+
+        await editor.updateSelection(
+          Selection(
+            start: Position(path: [0]),
+            end: Position(path: [0], offset: text.length),
+          ),
+        );
+        await tester.pumpAndSettle();
+
+        expect(service.selectionCounters.wordCount, 3);
+        expect(service.selectionCounters.charCount, text.length);
+        expect(wordCount, 3);
+        expect(charCount, text.length);
+
+        service.stop();
+
+        expect(service.selectionCounters.wordCount, 0);
+        expect(service.selectionCounters.charCount, 0);
         expect(wordCount, 0);
         expect(charCount, 0);