refactor: flutter style optional chaining

frontend/app_flowy/packages/flowy_editor/lib/src/document/text_delta.dart

@@ -276,14 +276,13 @@ class Delta extends Iterable<TextOperation> {
 
   Delta([List<TextOperation>? ops]) : _operations = ops ?? <TextOperation>[];
 
-  Delta addAll(Iterable<TextOperation> textOps) {
+  void addAll(Iterable<TextOperation> textOps) {
     textOps.forEach(add);
-    return this;
   }
 
-  Delta add(TextOperation textOp) {
+  void add(TextOperation textOp) {
     if (textOp.isEmpty) {
-      return this;
+      return;
     }
     _rawString = null;
 
@@ -291,12 +290,12 @@ class Delta extends Iterable<TextOperation> {
       final lastOp = _operations.last;
       if (lastOp is TextDelete && textOp is TextDelete) {
         lastOp.length += textOp.length;
-        return this;
+        return;
       }
       if (mapEquals(lastOp.attributes, textOp.attributes)) {
         if (lastOp is TextInsert && textOp is TextInsert) {
           lastOp.content += textOp.content;
-          return this;
+          return;
         }
         // if there is an delete before the insert
         // swap the order
@@ -304,17 +303,16 @@ class Delta extends Iterable<TextOperation> {
           _operations.removeLast();
           _operations.add(textOp);
           _operations.add(lastOp);
-          return this;
+          return;
         }
         if (lastOp is TextRetain && textOp is TextRetain) {
           lastOp.length += textOp.length;
-          return this;
+          return;
         }
       }
     }
 
     _operations.add(textOp);
-    return this;
   }
 
   Delta slice(int start, [int? end]) {
@@ -337,20 +335,13 @@ class Delta extends Iterable<TextOperation> {
     return result;
   }
 
-  Delta insert(String content, [Attributes? attributes]) {
-    final op = TextInsert(content, attributes);
-    return add(op);
-  }
+  void insert(String content, [Attributes? attributes]) =>
+      add(TextInsert(content, attributes));
 
-  Delta retain(int length, [Attributes? attributes]) {
-    final op = TextRetain(length, attributes);
-    return add(op);
-  }
+  void retain(int length, [Attributes? attributes]) =>
+      add(TextRetain(length, attributes));
 
-  Delta delete(int length) {
-    final op = TextDelete(length);
-    return add(op);
-  }
+  void delete(int length) => add(TextDelete(length));
 
   int get length {
     return _operations.fold(
@@ -409,7 +400,7 @@ class Delta extends Iterable<TextOperation> {
           if (!otherIter.hasNext &&
               delta._operations[delta._operations.length - 1] == newOp) {
             final rest = Delta(thisIter.rest());
-            return delta.concat(rest).chop();
+            return (delta + rest)..chop();
           }
         } else if (otherOp is TextDelete && (thisOp is TextRetain)) {
           delta.add(otherOp);
@@ -417,10 +408,10 @@ class Delta extends Iterable<TextOperation> {
       }
     }
 
-    return delta.chop();
+    return delta..chop();
   }
 
-  Delta concat(Delta other) {
+  Delta operator +(Delta other) {
     var ops = [..._operations];
     if (other._operations.isNotEmpty) {
       ops.add(other._operations[0]);
@@ -429,16 +420,15 @@ class Delta extends Iterable<TextOperation> {
     return Delta(ops);
   }
 
-  Delta chop() {
+  void chop() {
     if (_operations.isEmpty) {
-      return this;
+      return;
     }
     _rawString = null;
     final lastOp = _operations.last;
     if (lastOp is TextRetain && (lastOp.attributes?.length ?? 0) == 0) {
       _operations.removeLast();
     }
-    return this;
   }
 
   @override
@@ -477,7 +467,7 @@ class Delta extends Iterable<TextOperation> {
       }
       return previousValue;
     });
-    return inverted.chop();
+    return inverted..chop();
   }
 
   List<dynamic> toJson() {

frontend/app_flowy/packages/flowy_editor/lib/src/operation/transaction_builder.dart

@@ -113,22 +113,32 @@ class TransactionBuilder {
     }
     textEdit(
       node,
-      () => Delta().retain(index).insert(
-            content,
-            newAttributes,
-          ),
+      () => Delta()
+        ..retain(index)
+        ..insert(
+          content,
+          newAttributes,
+        ),
     );
     afterSelection = Selection.collapsed(
         Position(path: node.path, offset: index + content.length));
   }
 
   formatText(TextNode node, int index, int length, Attributes attributes) {
-    textEdit(node, () => Delta().retain(index).retain(length, attributes));
+    textEdit(
+        node,
+        () => Delta()
+          ..retain(index)
+          ..retain(length, attributes));
     afterSelection = beforeSelection;
   }
 
   deleteText(TextNode node, int index, int length) {
-    textEdit(node, () => Delta().retain(index).delete(length));
+    textEdit(
+        node,
+        () => Delta()
+          ..retain(index)
+          ..delete(length));
     afterSelection =
         Selection.collapsed(Position(path: node.path, offset: index));
   }
@@ -144,7 +154,10 @@ class TransactionBuilder {
     }
     textEdit(
       node,
-      () => Delta().retain(index).delete(length).insert(content, newAttributes),
+      () => Delta()
+        ..retain(index)
+        ..delete(length)
+        ..insert(content, newAttributes),
     );
     afterSelection = Selection.collapsed(
       Position(

frontend/app_flowy/packages/flowy_editor/lib/src/service/internal_key_event_handlers/copy_paste_handler.dart

@@ -67,7 +67,7 @@ _pasteHTML(EditorState editorState, String html) {
       final textNodeAtPath = nodeAtPath as TextNode;
       final firstTextNode = firstNode as TextNode;
       tb.textEdit(textNodeAtPath,
-          () => Delta().retain(startOffset).concat(firstTextNode.delta));
+          () => (Delta()..retain(startOffset)) + firstTextNode.delta);
       tb.setAfterSelection(Selection.collapsed(Position(
           path: path, offset: startOffset + firstTextNode.delta.length)));
       tb.commit();
@@ -93,17 +93,18 @@ _pasteMultipleLinesInText(
 
     tb.textEdit(
         textNodeAtPath,
-        () => Delta()
-            .retain(offset)
-            .delete(remain.length)
-            .concat(firstTextNode.delta));
+        () =>
+            (Delta()
+              ..retain(offset)
+              ..delete(remain.length)) +
+            firstTextNode.delta);
 
     final tailNodes = nodes.sublist(1);
     path[path.length - 1]++;
     if (tailNodes.isNotEmpty) {
       if (tailNodes.last.type == "text") {
         final tailTextNode = tailNodes.last as TextNode;
-        tailTextNode.delta = tailTextNode.delta.concat(remain);
+        tailTextNode.delta = tailTextNode.delta + remain;
       } else if (remain.length > 0) {
         tailNodes.add(TextNode(type: "text", delta: remain));
       }
@@ -151,7 +152,11 @@ _handlePastePlainText(EditorState editorState, String plainText) {
         editorState.document.nodeAtPath(selection.end.path)! as TextNode;
     final beginOffset = selection.end.offset;
     TransactionBuilder(editorState)
-      ..textEdit(node, () => Delta().retain(beginOffset).insert(lines[0]))
+      ..textEdit(
+          node,
+          () => Delta()
+            ..retain(beginOffset)
+            ..insert(lines[0]))
       ..setAfterSelection(Selection.collapsed(Position(
           path: selection.end.path, offset: beginOffset + lines[0].length)))
       ..commit();
@@ -175,17 +180,20 @@ _handlePastePlainText(EditorState editorState, String plainText) {
     final nodes = remains.map((e) {
       if (index++ == remains.length - 1) {
         return TextNode(
-            type: "text", delta: Delta().insert(e).addAll(insertedLineSuffix));
+            type: "text",
+            delta: Delta()
+              ..insert(e)
+              ..addAll(insertedLineSuffix));
       }
-      return TextNode(type: "text", delta: Delta().insert(e));
+      return TextNode(type: "text", delta: Delta()..insert(e));
     }).toList();
     // insert first line
     tb.textEdit(
         node,
         () => Delta()
-            .retain(beginOffset)
-            .insert(firstLine)
-            .delete(node.delta.length - beginOffset));
+          ..retain(beginOffset)
+          ..insert(firstLine)
+          ..delete(node.delta.length - beginOffset));
     // insert remains
     tb.insertNodes(path, nodes);
     tb.commit();
@@ -226,7 +234,10 @@ _deleteSelectedContent(EditorState editorState) {
     final tb = TransactionBuilder(editorState);
     final len = selection.end.offset - selection.start.offset;
     tb.textEdit(
-        textItem, () => Delta().retain(selection.start.offset).delete(len));
+        textItem,
+        () => Delta()
+          ..retain(selection.start.offset)
+          ..delete(len));
     tb.setAfterSelection(Selection.collapsed(selection.start));
     tb.commit();
     return;
@@ -240,8 +251,9 @@ _deleteSelectedContent(EditorState editorState) {
       final textItem = item as TextNode;
       final deleteLen = textItem.delta.length - selection.start.offset;
       tb.textEdit(textItem, () {
-        final delta = Delta();
-        delta.retain(selection.start.offset).delete(deleteLen);
+        final delta = Delta()
+          ..retain(selection.start.offset)
+          ..delete(deleteLen);
 
         if (endNode is TextNode) {
           final remain = endNode.delta.slice(selection.end.offset);

frontend/app_flowy/packages/flowy_editor/test/delta_test.dart

@@ -14,9 +14,12 @@ void main() {
         })
       ]);
 
-      final death = Delta().retain(12).insert("White", {
-        'color': '#fff',
-      }).delete(4);
+      final death = Delta()
+        ..retain(12)
+        ..insert("White", {
+          'color': '#fff',
+        })
+        ..delete(4);
 
       final restores = delta.compose(death);
       expect(restores.toList(), <TextOperation>[
@@ -26,164 +29,203 @@ void main() {
       ]);
     });
     test('compose()', () {
-      final a = Delta().insert('A');
-      final b = Delta().insert('B');
-      final expected = Delta().insert('B').insert('A');
+      final a = Delta()..insert('A');
+      final b = Delta()..insert('B');
+      final expected = Delta()
+        ..insert('B')
+        ..insert('A');
       expect(a.compose(b), expected);
     });
     test('insert + retain', () {
-      final a = Delta().insert('A');
-      final b = Delta().retain(1, {
-        'bold': true,
-        'color': 'red',
-      });
-      final expected = Delta().insert('A', {
-        'bold': true,
-        'color': 'red',
-      });
+      final a = Delta()..insert('A');
+      final b = Delta()
+        ..retain(1, {
+          'bold': true,
+          'color': 'red',
+        });
+      final expected = Delta()
+        ..insert('A', {
+          'bold': true,
+          'color': 'red',
+        });
       expect(a.compose(b), expected);
     });
     test('insert + delete', () {
-      final a = Delta().insert('A');
-      final b = Delta().delete(1);
+      final a = Delta()..insert('A');
+      final b = Delta()..delete(1);
       final expected = Delta();
       expect(a.compose(b), expected);
     });
     test('delete + insert', () {
-      final a = Delta().delete(1);
-      final b = Delta().insert('B');
-      final expected = Delta().insert('B').delete(1);
+      final a = Delta()..delete(1);
+      final b = Delta()..insert('B');
+      final expected = Delta()
+        ..insert('B')
+        ..delete(1);
       expect(a.compose(b), expected);
     });
     test('delete + retain', () {
-      final a = Delta().delete(1);
-      final b = Delta().retain(1, {
-        'bold': true,
-        'color': 'red',
-      });
-      final expected = Delta().delete(1).retain(1, {
-        'bold': true,
-        'color': 'red',
-      });
+      final a = Delta()..delete(1);
+      final b = Delta()
+        ..retain(1, {
+          'bold': true,
+          'color': 'red',
+        });
+      final expected = Delta()
+        ..delete(1)
+        ..retain(1, {
+          'bold': true,
+          'color': 'red',
+        });
       expect(a.compose(b), expected);
     });
     test('delete + delete', () {
-      final a = Delta().delete(1);
-      final b = Delta().delete(1);
-      final expected = Delta().delete(2);
+      final a = Delta()..delete(1);
+      final b = Delta()..delete(1);
+      final expected = Delta()..delete(2);
       expect(a.compose(b), expected);
     });
     test('retain + insert', () {
-      final a = Delta().retain(1, {'color': 'blue'});
-      final b = Delta().insert('B');
-      final expected = Delta().insert('B').retain(1, {
-        'color': 'blue',
-      });
+      final a = Delta()..retain(1, {'color': 'blue'});
+      final b = Delta()..insert('B');
+      final expected = Delta()
+        ..insert('B')
+        ..retain(1, {
+          'color': 'blue',
+        });
       expect(a.compose(b), expected);
     });
     test('retain + retain', () {
-      final a = Delta().retain(1, {
-        'color': 'blue',
-      });
-      final b = Delta().retain(1, {
-        'bold': true,
-        'color': 'red',
-      });
-      final expected = Delta().retain(1, {
-        'bold': true,
-        'color': 'red',
-      });
+      final a = Delta()
+        ..retain(1, {
+          'color': 'blue',
+        });
+      final b = Delta()
+        ..retain(1, {
+          'bold': true,
+          'color': 'red',
+        });
+      final expected = Delta()
+        ..retain(1, {
+          'bold': true,
+          'color': 'red',
+        });
       expect(a.compose(b), expected);
     });
     test('retain + delete', () {
-      final a = Delta().retain(1, {
-        'color': 'blue',
-      });
-      final b = Delta().delete(1);
-      final expected = Delta().delete(1);
+      final a = Delta()
+        ..retain(1, {
+          'color': 'blue',
+        });
+      final b = Delta()..delete(1);
+      final expected = Delta()..delete(1);
       expect(a.compose(b), expected);
     });
     test('insert in middle of text', () {
-      final a = Delta().insert('Hello');
-      final b = Delta().retain(3).insert('X');
-      final expected = Delta().insert('HelXlo');
+      final a = Delta()..insert('Hello');
+      final b = Delta()
+        ..retain(3)
+        ..insert('X');
+      final expected = Delta()..insert('HelXlo');
       expect(a.compose(b), expected);
     });
     test('insert and delete ordering', () {
-      final a = Delta().insert('Hello');
-      final b = Delta().insert('Hello');
-      final insertFirst = Delta().retain(3).insert('X').delete(1);
-      final deleteFirst = Delta().retain(3).delete(1).insert('X');
-      final expected = Delta().insert('HelXo');
+      final a = Delta()..insert('Hello');
+      final b = Delta()..insert('Hello');
+      final insertFirst = Delta()
+        ..retain(3)
+        ..insert('X')
+        ..delete(1);
+      final deleteFirst = Delta()
+        ..retain(3)
+        ..delete(1)
+        ..insert('X');
+      final expected = Delta()..insert('HelXo');
       expect(a.compose(insertFirst), expected);
       expect(b.compose(deleteFirst), expected);
     });
     test('delete entire text', () {
-      final a = Delta().retain(4).insert('Hello');
-      final b = Delta().delete(9);
-      final expected = Delta().delete(4);
+      final a = Delta()
+        ..retain(4)
+        ..insert('Hello');
+      final b = Delta()..delete(9);
+      final expected = Delta()..delete(4);
       expect(a.compose(b), expected);
     });
     test('retain more than length of text', () {
-      final a = Delta().insert('Hello');
-      final b = Delta().retain(10);
-      final expected = Delta().insert('Hello');
+      final a = Delta()..insert('Hello');
+      final b = Delta()..retain(10);
+      final expected = Delta()..insert('Hello');
       expect(a.compose(b), expected);
     });
     test('retain start optimization', () {
       final a = Delta()
-          .insert('A', {'bold': true})
-          .insert('B')
-          .insert('C', {'bold': true})
-          .delete(1);
-      final b = Delta().retain(3).insert('D');
+        ..insert('A', {'bold': true})
+        ..insert('B')
+        ..insert('C', {'bold': true})
+        ..delete(1);
+      final b = Delta()
+        ..retain(3)
+        ..insert('D');
       final expected = Delta()
-          .insert('A', {'bold': true})
-          .insert('B')
-          .insert('C', {'bold': true})
-          .insert('D')
-          .delete(1);
+        ..insert('A', {'bold': true})
+        ..insert('B')
+        ..insert('C', {'bold': true})
+        ..insert('D')
+        ..delete(1);
       expect(a.compose(b), expected);
     });
     test('retain end optimization', () {
       final a = Delta()
-          .insert('A', {'bold': true})
-          .insert('B')
-          .insert('C', {'bold': true});
-      final b = Delta().delete(1);
-      final expected = Delta().insert('B').insert('C', {'bold': true});
+        ..insert('A', {'bold': true})
+        ..insert('B')
+        ..insert('C', {'bold': true});
+      final b = Delta()..delete(1);
+      final expected = Delta()
+        ..insert('B')
+        ..insert('C', {'bold': true});
       expect(a.compose(b), expected);
     });
     test('retain end optimization join', () {
       final a = Delta()
-          .insert('A', {'bold': true})
-          .insert('B')
-          .insert('C', {'bold': true})
-          .insert('D')
-          .insert('E', {'bold': true})
-          .insert('F');
-      final b = Delta().retain(1).delete(1);
+        ..insert('A', {'bold': true})
+        ..insert('B')
+        ..insert('C', {'bold': true})
+        ..insert('D')
+        ..insert('E', {'bold': true})
+        ..insert('F');
+      final b = Delta()
+        ..retain(1)
+        ..delete(1);
       final expected = Delta()
-          .insert('AC', {'bold': true})
-          .insert('D')
-          .insert('E', {'bold': true})
-          .insert('F');
+        ..insert('AC', {'bold': true})
+        ..insert('D')
+        ..insert('E', {'bold': true})
+        ..insert('F');
       expect(a.compose(b), expected);
     });
   });
   group('invert', () {
     test('insert', () {
-      final delta = Delta().retain(2).insert('A');
-      final base = Delta().insert('12346');
-      final expected = Delta().retain(2).delete(1);
+      final delta = Delta()
+        ..retain(2)
+        ..insert('A');
+      final base = Delta()..insert('12346');
+      final expected = Delta()
+        ..retain(2)
+        ..delete(1);
       final inverted = delta.invert(base);
       expect(expected, inverted);
       expect(base.compose(delta).compose(inverted), base);
     });
     test('delete', () {
-      final delta = Delta().retain(2).delete(3);
-      final base = Delta().insert('123456');
-      final expected = Delta().retain(2).insert('345');
+      final delta = Delta()
+        ..retain(2)
+        ..delete(3);
+      final base = Delta()..insert('123456');
+      final expected = Delta()
+        ..retain(2)
+        ..insert('345');
       final inverted = delta.invert(base);
       expect(expected, inverted);
       expect(base.compose(delta).compose(inverted), base);
@@ -199,7 +241,10 @@ void main() {
   });
   group('json', () {
     test('toJson()', () {
-      final delta = Delta().retain(2).insert('A').delete(3);
+      final delta = Delta()
+        ..retain(2)
+        ..insert('A')
+        ..delete(3);
       expect(delta.toJson(), [
         {'retain': 2},
         {'insert': 'A'},
@@ -207,8 +252,9 @@ void main() {
       ]);
     });
     test('attributes', () {
-      final delta =
-          Delta().retain(2, {'bold': true}).insert('A', {'italic': true});
+      final delta = Delta()
+        ..retain(2, {'bold': true})
+        ..insert('A', {'italic': true});
       expect(delta.toJson(), [
         {
           'retain': 2,
@@ -226,7 +272,10 @@ void main() {
         {'insert': 'A'},
         {'delete': 3},
       ]);
-      final expected = Delta().retain(2).insert('A').delete(3);
+      final expected = Delta()
+        ..retain(2)
+        ..insert('A')
+        ..delete(3);
       expect(delta, expected);
     });
   });