| // Copyright (c) 2018, 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'Avoid shadowing type parameters.'; |
| |
| const _details = r''' |
| |
| **AVOID** shadowing type parameters. |
| |
| **BAD:** |
| ``` |
| class A<T> { |
| void fn<T>() {} |
| } |
| ``` |
| |
| **GOOD:** |
| ``` |
| class A<T> { |
| void fn<U>() {} |
| } |
| ``` |
| |
| '''; |
| |
| class AvoidShadowingTypeParameters extends LintRule implements NodeLintRule { |
| AvoidShadowingTypeParameters() |
| : super( |
| name: 'avoid_shadowing_type_parameters', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| final visitor = _Visitor(this); |
| registry.addFunctionDeclarationStatement(this, visitor); |
| registry.addGenericTypeAlias(this, visitor); |
| registry.addMethodDeclaration(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitFunctionDeclarationStatement(FunctionDeclarationStatement node) { |
| var functionExpression = node.functionDeclaration.functionExpression; |
| if (functionExpression.typeParameters == null) { |
| return; |
| } |
| _checkAncestorParameters(functionExpression.typeParameters, node); |
| } |
| |
| @override |
| void visitGenericTypeAlias(GenericTypeAlias node) { |
| if (node.functionType?.typeParameters == null) { |
| return; |
| } |
| _checkForShadowing(node.functionType.typeParameters, node.typeParameters); |
| } |
| |
| @override |
| void visitMethodDeclaration(MethodDeclaration node) { |
| if (node.typeParameters == null) { |
| return; |
| } |
| |
| // Static methods have nothing above them to shadow. |
| if (!node.isStatic) { |
| _checkAncestorParameters(node.typeParameters, node); |
| } |
| } |
| |
| // Check the ancestors of [node] for type parameter shadowing. |
| void _checkAncestorParameters( |
| TypeParameterList typeParameters, AstNode node) { |
| var parent = node.parent; |
| |
| while (parent != null) { |
| if (parent is ClassOrMixinDeclaration) { |
| _checkForShadowing(typeParameters, parent.typeParameters); |
| } else if (parent is ExtensionDeclaration) { |
| _checkForShadowing(typeParameters, parent.typeParameters); |
| } else if (parent is MethodDeclaration) { |
| _checkForShadowing(typeParameters, parent.typeParameters); |
| } else if (parent is FunctionDeclaration) { |
| _checkForShadowing( |
| typeParameters, parent.functionExpression.typeParameters); |
| } |
| parent = parent.parent; |
| } |
| } |
| |
| // Check whether any of [typeParameters] shadow [ancestorTypeParameters]. |
| void _checkForShadowing(TypeParameterList typeParameters, |
| TypeParameterList ancestorTypeParameters) { |
| if (ancestorTypeParameters == null) { |
| return; |
| } |
| |
| var typeParameterIds = typeParameters.typeParameters.map((tp) => tp.name); |
| var ancestorTypeParameterNames = |
| ancestorTypeParameters.typeParameters.map((tp) => tp.name.name); |
| var shadowingTypeParameters = typeParameterIds |
| .where((tp) => ancestorTypeParameterNames.contains(tp.name)); |
| |
| shadowingTypeParameters.forEach(rule.reportLint); |
| } |
| } |