| // Copyright (c) 2019, 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'; |
| |
| const _desc = r'Prefer if elements to conditional expressions where possible.'; |
| |
| const _details = r''' |
| When building collections, it is preferable to use `if` elements rather than |
| conditionals. |
| |
| **BAD:** |
| ``` |
| Widget build(BuildContext context) { |
| return Row( |
| children: [ |
| IconButton(icon: Icon(Icons.menu)), |
| Expanded(child: title), |
| isAndroid ? IconButton(icon: Icon(Icons.search)) : null, |
| ].where((child) => child != null).toList(), |
| ); |
| } |
| ``` |
| |
| **GOOD:** |
| ``` |
| Widget build(BuildContext context) { |
| return Row( |
| children: [ |
| IconButton(icon: Icon(Icons.menu)), |
| Expanded(child: title), |
| if (isAndroid) IconButton(icon: Icon(Icons.search)), |
| ] |
| ); |
| } |
| '''; |
| |
| class PreferIfElementsToConditionalExpressions extends LintRule |
| implements NodeLintRule { |
| PreferIfElementsToConditionalExpressions() |
| : super( |
| name: 'prefer_if_elements_to_conditional_expressions', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| final visitor = _Visitor(this); |
| registry.addConditionalExpression(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitConditionalExpression(ConditionalExpression node) { |
| AstNode nodeToReplace = node; |
| var parent = node.parent; |
| while (parent is ParenthesizedExpression) { |
| nodeToReplace = parent; |
| parent = parent.parent; |
| } |
| if (parent is ListLiteral || (parent is SetOrMapLiteral && parent.isSet)) { |
| rule.reportLint(nodeToReplace); |
| } |
| } |
| } |