Custom undo/redo implementation (#97)

lib/src/code_field/actions/redo.dart

@@ -0,0 +1,17 @@
+import 'package:flutter/widgets.dart';
+
+import '../code_controller.dart';
+
+class RedoAction extends Action<RedoTextIntent> {
+  final CodeController controller;
+
+  RedoAction({
+    required this.controller,
+  });
+
+  @override
+  Object? invoke(RedoTextIntent intent) {
+    controller.historyController.redo();
+    return null;
+  }
+}

lib/src/code_field/actions/undo.dart

@@ -0,0 +1,17 @@
+import 'package:flutter/widgets.dart';
+
+import '../code_controller.dart';
+
+class UndoAction extends Action<UndoTextIntent> {
+  final CodeController controller;
+
+  UndoAction({
+    required this.controller,
+  });
+
+  @override
+  Object? invoke(UndoTextIntent intent) {
+    controller.historyController.undo();
+    return null;
+  }
+}

lib/src/code_field/code_controller.dart

@@ -17,9 +17,13 @@ import '../code_modifiers/indent_code_modifier.dart';
 import '../code_modifiers/tab_code_modifier.dart';
 import '../code_theme/code_theme.dart';
 import '../code_theme/code_theme_data.dart';
+import '../history/code_history_controller.dart';
+import '../history/code_history_record.dart';
 import '../named_sections/parsers/abstract.dart';
 import '../wip/autocomplete/popup_controller.dart';
 import 'actions/copy.dart';
+import 'actions/redo.dart';
+import 'actions/undo.dart';
 import 'editor_params.dart';
 import 'span_builder.dart';
 
@@ -102,9 +106,12 @@ class CodeController extends TextEditingController {
   RegExp? styleRegExp;
   late PopupController popupController;
   final autocompleter = Autocompleter();
+  late final historyController = CodeHistoryController(codeController: this);
 
-  late final actions = {
+  late final actions = <Type, Action<Intent>>{
     CopySelectionTextIntent: CopyAction(controller: this),
+    RedoTextIntent: RedoAction(controller: this),
+    UndoTextIntent: UndoAction(controller: this),
   };
 
   CodeController({
@@ -301,7 +308,14 @@ class CodeController extends TextEditingController {
 
   @override
   set value(TextEditingValue newValue) {
-    if (newValue.text != super.value.text) {
+    final hasTextChanged = newValue.text != super.value.text;
+    final hasSelectionChanged = newValue.selection != super.value.selection;
+
+    if (!hasTextChanged && !hasSelectionChanged) {
+      return;
+    }
+
+    if (hasTextChanged) {
       final loc = _insertedLoc(text, newValue.text);
 
       if (loc != null) {
@@ -339,9 +353,6 @@ class CodeController extends TextEditingController {
       //print('\n\n${_code.text}');
     }
 
-    bool hasTextChanged = newValue.text != super.value.text;
-    bool hasSelectionChanged = newValue.selection != super.value.selection;
-
     //Because of this part of code ctrl + z dont't work. But maybe it's important, so please don't delete.
     // Now fix the textfield for web
     // if (_webSpaceFix) {
@@ -352,7 +363,9 @@ class CodeController extends TextEditingController {
       _webSpaceFix ? _middleDotsToSpaces(newValue.text) : newValue.text,
     );
 
+    historyController.beforeChanged(_code, newValue.selection);
     super.value = newValue;
+
     if (hasTextChanged) {
       autocompleter.blacklist = [newValue.wordAtCursor ?? ''];
       autocompleter.setText(this, text);
@@ -362,6 +375,15 @@ class CodeController extends TextEditingController {
     }
   }
 
+  void applyHistoryRecord(CodeHistoryRecord record) {
+    _code = record.code;
+
+    super.value = TextEditingValue(
+      text: code.visibleText,
+      selection: record.selection,
+    );
+  }
+
   Code get code => _code;
 
   CodeEditResult? _getEditResultNotBreakingReadOnly(TextEditingValue newValue) {

lib/src/code_field/code_field.dart

@@ -32,14 +32,36 @@ final _shortcuts = {
     LogicalKeyboardKey.control,
     LogicalKeyboardKey.keyX,
   ): const CopySelectionTextIntent.cut(SelectionChangedCause.keyboard),
-    LogicalKeySet(
+  LogicalKeySet(
     LogicalKeyboardKey.meta,
     LogicalKeyboardKey.keyX,
   ): const CopySelectionTextIntent.cut(SelectionChangedCause.keyboard),
   LogicalKeySet(
     LogicalKeyboardKey.shift,
     LogicalKeyboardKey.delete,
   ): const CopySelectionTextIntent.cut(SelectionChangedCause.keyboard),
+
+  // Undo
+  LogicalKeySet(
+    LogicalKeyboardKey.control,
+    LogicalKeyboardKey.keyZ,
+  ): const UndoTextIntent(SelectionChangedCause.keyboard),
+  LogicalKeySet(
+    LogicalKeyboardKey.meta,
+    LogicalKeyboardKey.keyZ,
+  ): const UndoTextIntent(SelectionChangedCause.keyboard),
+
+  // Redo
+  LogicalKeySet(
+    LogicalKeyboardKey.shift,
+    LogicalKeyboardKey.control,
+    LogicalKeyboardKey.keyZ,
+  ): const RedoTextIntent(SelectionChangedCause.keyboard),
+  LogicalKeySet(
+    LogicalKeyboardKey.shift,
+    LogicalKeyboardKey.meta,
+    LogicalKeyboardKey.keyZ,
+  ): const RedoTextIntent(SelectionChangedCause.keyboard),
 };
 
 class CodeField extends StatefulWidget {

lib/src/code_field/text_editing_value.dart

@@ -74,10 +74,6 @@ extension TextEditingValueExtension on TextEditingValue {
     return replaced(selection, '');
   }
 
-  TextEditingValue replacedSelection(String value) {
-    return replaced(selection, value);
-  }
-
   TextEditingValue replacedText(String newText) {
     if (newText == text) {
       return this;

lib/src/code_field/text_selection.dart

@@ -13,4 +13,12 @@ extension TextSelectionExtension on TextSelection {
   bool get isSelectionNormalized {
     return baseOffset <= extentOffset;
   }
+
+  bool hasMovedOneCharacterRight(TextSelection old) {
+    if (!old.isCollapsed || !isCollapsed) {
+      return false;
+    }
+
+    return start == old.start + 1;
+  }
 }

lib/src/history/code_history_controller.dart

@@ -0,0 +1,137 @@
+import 'dart:async';
+
+import 'package:flutter/services.dart';
+import 'package:meta/meta.dart';
+
+import '../code/code.dart';
+import '../code_field/code_controller.dart';
+import '../code_field/text_selection.dart';
+import 'code_history_record.dart';
+import 'limit_stack.dart';
+
+/// A custom undo/redo implementation for [CodeController].
+///
+/// This is needed because the built-in implementation listens to the
+/// visible text changes in [TextEditingController] and sets that on undo/redo.
+/// This would delete hidden ranges and folded blocks.
+///
+/// With this controller, new records are created:
+/// - If the line count has changed.
+/// - After the [idle] duration if the text has changed since the last record.
+/// - On any selection change other than that of inserting a single
+///   character, if the text has changed since the last record.
+class CodeHistoryController {
+  final CodeController codeController;
+  Code lastCode;
+  TextSelection lastSelection;
+  int _currentRecordIndex = 0;
+  bool _isTextChanged = false;
+  Timer? _debounceTimer;
+
+  @visibleForTesting
+  final stack = LimitStack<CodeHistoryRecord>(maxLength: limit);
+
+  static const idle = Duration(seconds: 5);
+  static const limit = 100;
+
+  CodeHistoryController({
+    required this.codeController,
+  })  : lastCode = codeController.code,
+        lastSelection = codeController.value.selection {
+    _push();
+  }
+
+  void beforeChanged(Code code, TextSelection selection) {
+    _dropRedoIfNeed();
+    bool shouldSave = false;
+
+    if (_isTextChanged) {
+      shouldSave = code.lines.lines.length != lastCode.lines.lines.length;
+    }
+
+    if (!shouldSave) {
+      if (lastCode.text != code.text) {
+        _isTextChanged = true;
+      }
+
+      if (_isTextChanged) {
+        final isText1CharLonger = code.text.length == lastCode.text.length + 1;
+        final isTypingContinuous = isText1CharLonger &&
+            selection.hasMovedOneCharacterRight(lastSelection);
+
+        if (isTypingContinuous) {
+          _setTimer();
+        } else {
+          shouldSave = true;
+        }
+      }
+    }
+
+    if (shouldSave) {
+      _push();
+    }
+
+    lastCode = code;
+    lastSelection = selection;
+  }
+
+  void _dropRedoIfNeed() {
+    stack.removeAfter(_currentRecordIndex + 1);
+  }
+
+  void undo() {
+    if (_isTextChanged) {
+      _push();
+    }
+
+    if (_currentRecordIndex == 0) {
+      return;
+    }
+
+    _applyHistoryRecord(stack[--_currentRecordIndex]);
+  }
+
+  void redo() {
+    if (_currentRecordIndex == stack.length - 1) {
+      return;
+    }
+
+    _applyHistoryRecord(stack[++_currentRecordIndex]);
+  }
+
+  void _applyHistoryRecord(CodeHistoryRecord record) {
+    lastCode = record.code;
+    lastSelection = record.selection;
+
+    codeController.applyHistoryRecord(record);
+  }
+
+  void _push() {
+    _debounceTimer?.cancel();
+    _pushRecord(_createRecord());
+    _isTextChanged = false;
+  }
+
+  void _setTimer() {
+    _debounceTimer?.cancel();
+    _debounceTimer = Timer(idle, _push);
+  }
+
+  CodeHistoryRecord _createRecord() {
+    return CodeHistoryRecord(
+      code: lastCode,
+      selection: lastSelection,
+    );
+  }
+
+  void _pushRecord(CodeHistoryRecord record) {
+    stack.push(record);
+    _currentRecordIndex = stack.length - 1;
+  }
+
+  void deleteHistory() {
+    stack.clear();
+    _push();
+    _currentRecordIndex = 0;
+  }
+}

lib/src/history/code_history_record.dart

@@ -0,0 +1,20 @@
+import 'package:equatable/equatable.dart';
+import 'package:flutter/services.dart';
+
+import '../code/code.dart';
+
+class CodeHistoryRecord with EquatableMixin {
+  final Code code;
+  final TextSelection selection;
+
+  const CodeHistoryRecord({
+    required this.code,
+    required this.selection,
+  });
+
+  @override
+  List<Object> get props => [
+        code,
+        selection,
+      ];
+}

lib/src/history/limit_stack.dart

@@ -0,0 +1,34 @@
+class LimitStack<T> extends Iterable<T> {
+  final int maxLength;
+  final _items = <T>[];
+
+  LimitStack({
+    required this.maxLength,
+  });
+
+  @override
+  int get length => _items.length;
+
+  void push(T value) {
+    _items.add(value);
+
+    if (_items.length > maxLength) {
+      _items.removeRange(0, _items.length - maxLength);
+    }
+  }
+
+  void removeAfter(int n) {
+    _items.removeRange(n, _items.length);
+  }
+
+  void clear() {
+    _items.clear();
+  }
+
+  T operator [](int n) {
+    return _items[n];
+  }
+
+  @override
+  Iterator<T> get iterator => _items.iterator;
+}

pubspec.yaml

@@ -22,6 +22,7 @@ dependencies:
   tuple: ^2.0.1
 
 dev_dependencies:
+  fake_async: ^1.3.1
   flutter_test: { sdk: flutter }
   total_lints: ^2.18.0
 

test/src/code_field/code_controller_folding_test.dart

@@ -1,8 +1,8 @@
 import 'package:flutter/widgets.dart';
-import 'package:flutter_code_editor/src/code_field/text_editing_value.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 import '../common/create_app.dart';
+import '../common/text_editing_value.dart';
 import '../common/widget_tester.dart';
 
 const _code = '''

test/src/code_field/code_controller_hidden_ranges_test.dart

@@ -5,6 +5,7 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:highlight/languages/java.dart';
 
 import '../common/create_app.dart';
+import '../common/text_editing_value.dart';
 
 const _text = '''
 // [START section2]