| // Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| import 'package:analyzer/dart/ast/ast.dart'; |
| import 'package:analyzer/dart/ast/visitor.dart'; |
| |
| import '../analyzer.dart'; |
| import '../util/flutter_utils.dart'; |
| |
| const _desc = r'SizedBox for whitespace.'; |
| |
| const _details = r'''Use SizedBox to add whitespace to a layout. |
| |
| A `Container` is a heavier Widget than a `SizedBox`, and as bonus, `SizedBox` |
| has a `const` constructor. |
| |
| **BAD:** |
| ```dart |
| Widget buildRow() { |
| return Row( |
| children: <Widget>[ |
| const MyLogo(), |
| Container(width: 4), |
| const Expanded( |
| child: Text('...'), |
| ), |
| ], |
| ); |
| } |
| ``` |
| |
| **GOOD:** |
| ```dart |
| Widget buildRow() { |
| return Row( |
| children: const <Widget>[ |
| MyLogo(), |
| SizedBox(width: 4), |
| Expanded( |
| child: Text('...'), |
| ), |
| ], |
| ); |
| } |
| ``` |
| '''; |
| |
| class SizedBoxForWhitespace extends LintRule implements NodeLintRule { |
| SizedBoxForWhitespace() |
| : super( |
| name: 'sized_box_for_whitespace', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| final visitor = _Visitor(this); |
| |
| registry.addInstanceCreationExpression(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitInstanceCreationExpression(InstanceCreationExpression node) { |
| if (!isExactWidgetTypeContainer(node.staticType)) { |
| return; |
| } |
| |
| final visitor = _WidthOrHeightArgumentVisitor(); |
| node.visitChildren(visitor); |
| if (visitor.seenIncompatibleParams) { |
| return; |
| } |
| if (visitor.seenChild && (visitor.seenWidth || visitor.seenHeight) || |
| visitor.seenWidth && visitor.seenHeight) { |
| rule.reportLint(node.constructorName); |
| } |
| } |
| } |
| |
| class _WidthOrHeightArgumentVisitor extends SimpleAstVisitor<void> { |
| var seenWidth = false; |
| var seenHeight = false; |
| var seenChild = false; |
| var seenIncompatibleParams = false; |
| |
| @override |
| void visitArgumentList(ArgumentList node) { |
| for (final name in node.arguments |
| .cast<NamedExpression>() |
| .map((arg) => arg.name.label.name)) { |
| if (name == 'width') { |
| seenWidth = true; |
| } else if (name == 'height') { |
| seenHeight = true; |
| } else if (name == 'child') { |
| seenChild = true; |
| } else if (name == 'key') { |
| // key doesn't matter (both SiezdBox and Container have it) |
| } else { |
| seenIncompatibleParams = true; |
| } |
| } |
| } |
| } |