| // 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 'dart:collection'; |
| |
| import 'package:analyzer/dart/ast/ast.dart'; |
| import 'package:analyzer/dart/ast/visitor.dart'; |
| import 'package:analyzer/dart/element/type.dart'; |
| import 'package:linter/src/analyzer.dart'; |
| import 'package:linter/src/util/dart_type_utilities.dart'; |
| |
| const _desc = |
| r'Only throw instances of classes extending either Exception or Error.'; |
| |
| const _details = r''' |
| |
| **DO** throw only instances of classes that extend `dart.core.Error` or |
| `dart.core.Exception`. |
| |
| Throwing instances that do not extend `Error` or `Exception` is a bad practice; |
| doing this is usually a hack for something that should be implemented more |
| thoroughly. |
| |
| **BAD:** |
| ``` |
| void throwString() { |
| throw 'hello world!'; // LINT |
| } |
| ``` |
| |
| **GOOD:** |
| ``` |
| void throwArgumentError() { |
| Error error = new ArgumentError('oh!'); |
| throw error; // OK |
| } |
| ``` |
| |
| '''; |
| |
| const _errorClassName = 'Error'; |
| |
| const _exceptionClassName = 'Exception'; |
| |
| const _library = 'dart.core'; |
| final LinkedHashSet<InterfaceTypeDefinition> _interfaceDefinitions = |
| new LinkedHashSet<InterfaceTypeDefinition>.from([ |
| new InterfaceTypeDefinition(_exceptionClassName, _library), |
| new InterfaceTypeDefinition(_errorClassName, _library) |
| ]); |
| bool _isThrowable(DartType type) => |
| type == null || |
| type.isDynamic || |
| DartTypeUtilities.implementsAnyInterface(type, _interfaceDefinitions); |
| |
| class OnlyThrowErrors extends LintRule implements NodeLintRule { |
| OnlyThrowErrors() |
| : super( |
| name: 'only_throw_errors', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors(NodeLintRegistry registry, |
| [LinterContext context]) { |
| final visitor = new _Visitor(this); |
| registry.addThrowExpression(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitThrowExpression(ThrowExpression node) { |
| if (node.expression is Literal) { |
| rule.reportLint(node.expression); |
| return; |
| } |
| |
| if (!_isThrowable(node.expression.staticType)) { |
| rule.reportLint(node.expression); |
| } |
| } |
| } |