feat: custom slice function

example/lib/pages/editor.dart

@@ -31,6 +31,13 @@ class _EditorState extends State<Editor> {
   EditorState? editorState;
   WordCountService? wordCountService;
 
+  @override
+  void initState() {
+    super.initState();
+
+    appflowyEditorSliceAttributes = sliceAttributes;
+  }
+
   @override
   void didUpdateWidget(covariant Editor oldWidget) {
     if (oldWidget.jsonString != widget.jsonString) {
@@ -156,4 +163,60 @@ class _EditorState extends State<Editor> {
       ],
     );
   }
+
+  Attributes? sliceAttributes(Delta delta, int index) {
+    if (index < 0) {
+      return null;
+    }
+
+    // if the index == 0, slice the attributes from the next position.
+    if (index == 0 && delta.isNotEmpty) {
+      final attributes = delta.slice(index, index + 1).firstOrNull?.attributes;
+      if (attributes == null) {
+        return null;
+      }
+
+      if (!isSupportSliced(attributes)) {
+        return null;
+      }
+
+      return attributes;
+    }
+
+    // if the index is not 0, slice the attributes from the previous position.
+    final prevAttributes =
+        delta.slice(index - 1, index).firstOrNull?.attributes;
+    if (prevAttributes == null) {
+      return null;
+    }
+    // if the prevAttributes doesn't include the code, return it.
+    // Otherwise, check if the nextAttributes includes the code.
+    if (!prevAttributes.keys.any(
+      (element) => element == AppFlowyRichTextKeys.code,
+    )) {
+      return prevAttributes;
+    }
+
+    // check if the nextAttributes includes the code.
+    final nextAttributes =
+        delta.slice(index, index + 1).firstOrNull?.attributes;
+    if (nextAttributes == null) {
+      return prevAttributes..remove(AppFlowyRichTextKeys.code);
+    }
+
+    // if the nextAttributes doesn't include the code, exclude the code format.
+    if (!nextAttributes.keys.any(
+      (element) => element == AppFlowyRichTextKeys.code,
+    )) {
+      return prevAttributes..remove(AppFlowyRichTextKeys.code);
+    }
+
+    return prevAttributes;
+  }
+
+  bool isSupportSliced(Attributes attributes) {
+    return attributes.keys.every(
+      (element) => AppFlowyRichTextKeys.supportSliced.contains(element),
+    );
+  }
 }

lib/src/core/document/text_delta.dart

@@ -6,6 +6,57 @@ import 'package:diff_match_patch/diff_match_patch.dart' as diff_match_patch;
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 
+typedef AppFlowyEditorSliceAttributes = Attributes? Function(
+  Delta delta,
+  int index,
+);
+
+AppFlowyEditorSliceAttributes? defaultAppFlowyEditorSliceAttributes = (
+  delta,
+  index,
+) {
+  if (index < 0) {
+    return null;
+  }
+
+  Attributes? attributes;
+
+  // if the index == 0, slice the attributes from the next position.
+  if (index == 0 && delta.isNotEmpty) {
+    attributes = delta.slice(index, index + 1).firstOrNull?.attributes;
+  } else {
+    attributes = delta.slice(index - 1, index).firstOrNull?.attributes;
+  }
+
+  if (attributes == null) {
+    return null;
+  }
+
+  if (!attributes.keys.every(
+    (element) => AppFlowyRichTextKeys.supportSliced.contains(element),
+  )) {
+    AppFlowyEditorLog.editor.info(
+      'The attributes: $attributes is not supported in sliceAttributes.',
+    );
+    return null;
+  }
+
+  return attributes;
+};
+
+/// Default slice attributes function.
+///
+/// You can override the default slice attributes function by customizing
+/// different slice rules, and fallback to the default one if not specified.
+///
+/// Rules
+/// 1. If the index is less than 0, return null.
+/// 2. If the index is 0, slice the attributes from the next position.
+/// 3. If the index is greater than 0, slice the attributes from the previous position.
+/// 4. If the attributes is not supported, return null.
+AppFlowyEditorSliceAttributes? appflowyEditorSliceAttributes =
+    defaultAppFlowyEditorSliceAttributes;
+
 // constant number: 2^53 - 1
 const int _maxInt = 9007199254740991;
 
@@ -515,33 +566,7 @@ class Delta extends Iterable<TextOperation> {
   }
 
   Attributes? sliceAttributes(int index) {
-    if (index < 0) {
-      return null;
-    }
-
-    Attributes? attributes;
-
-    // if the index == 0, slice the attributes from the next position.
-    if (index == 0 && length >= 1) {
-      attributes = slice(index, index + 1).firstOrNull?.attributes;
-    } else {
-      attributes = slice(index - 1, index).firstOrNull?.attributes;
-    }
-
-    if (attributes == null) {
-      return null;
-    }
-
-    if (!attributes.keys.every(
-      (element) => AppFlowyRichTextKeys.supportSliced.contains(element),
-    )) {
-      AppFlowyEditorLog.editor.info(
-        'The attributes: $attributes is not supported in sliceAttributes.',
-      );
-      return null;
-    }
-
-    return attributes;
+    return appflowyEditorSliceAttributes?.call(this, index);
   }
 }
 

lib/src/editor/editor_component/service/ime/delta_input_on_non_text_update_impl.dart

@@ -140,6 +140,8 @@ Future<bool> _checkIfBacktickPressed(
     AppFlowyEditorLog.input.debug('format failed');
     // revert the transaction
     editorState.undoManager.undo();
+  } else {
+    editorState.sliceUpcomingAttributes = false;
   }
 
   return true;

lib/src/editor_state.dart

@@ -190,7 +190,15 @@ class EditorState {
   ///
   /// If the value is true, the upcoming attributes will be sliced.
   /// If the value is false, the upcoming attributes will be skipped.
-  bool sliceUpcomingAttributes = true;
+  bool _sliceUpcomingAttributes = true;
+  bool get sliceUpcomingAttributes => _sliceUpcomingAttributes;
+  set sliceUpcomingAttributes(bool value) {
+    if (value == _sliceUpcomingAttributes) {
+      return;
+    }
+    AppFlowyEditorLog.input.debug('sliceUpcomingAttributes: $value');
+    _sliceUpcomingAttributes = value;
+  }
 
   final UndoManager undoManager = UndoManager();