| // Copyright (c) 2016, 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 '../utils.dart'; |
| |
| const _desc = r'Avoid empty catch blocks.'; |
| |
| const _details = r''' |
| |
| **AVOID** empty catch blocks. |
| |
| In general, empty catch blocks should be avoided. In cases where they are |
| intended, a comment should be provided to explain why exceptions are being |
| caught and suppressed. Alternatively, the exception identifier can be named with |
| underscores (e.g., `_`) to indicate that we intend to skip it. |
| |
| **BAD:** |
| ``` |
| try { |
| ... |
| } catch(exception) { } |
| ``` |
| |
| **GOOD:** |
| ``` |
| try { |
| ... |
| } catch(e) { |
| // ignored, really. |
| } |
| |
| // Alternatively: |
| try { |
| ... |
| } catch(_) { } |
| |
| // Better still: |
| try { |
| ... |
| } catch(e) { |
| doSomething(e); |
| } |
| ``` |
| |
| '''; |
| |
| class EmptyCatches extends LintRule implements NodeLintRule { |
| EmptyCatches() |
| : super( |
| name: 'empty_catches', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| final visitor = _Visitor(this); |
| registry.addCatchClause(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitCatchClause(CatchClause node) { |
| // Skip exceptions named with underscores. |
| final exceptionParameter = node.exceptionParameter; |
| if (exceptionParameter != null && |
| isJustUnderscores(exceptionParameter.name)) { |
| return; |
| } |
| |
| final body = node.body; |
| if (node.body.statements.isEmpty && |
| body.rightBracket?.precedingComments == null) { |
| rule.reportLint(body); |
| } |
| } |
| } |