| // 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'; |
| import '../util/dart_type_utilities.dart'; |
| |
| const _desc = r'Prefer to use whereType on iterable.'; |
| |
| const _details = r''' |
| |
| **PREFER** `iterable.whereType<T>()` over `iterable.where((e) => e is T)`. |
| |
| **BAD:** |
| ``` |
| iterable.where((e) => e is MyClass) |
| ``` |
| |
| **GOOD:** |
| ``` |
| iterable.whereType<MyClass>() |
| ``` |
| |
| '''; |
| |
| class PreferIterableWhereType extends LintRule implements NodeLintRule { |
| PreferIterableWhereType() |
| : super( |
| name: 'prefer_iterable_whereType', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| final visitor = _Visitor(this); |
| registry.addMethodInvocation(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitMethodInvocation(MethodInvocation node) { |
| if (node.methodName.name != 'where') return; |
| final target = node.realTarget; |
| if (target == null || |
| !DartTypeUtilities.implementsInterface( |
| target.staticType, 'Iterable', 'dart.core')) { |
| return; |
| } |
| |
| final args = node.argumentList?.arguments; |
| if (args == null || args.length != 1) return; |
| |
| final arg = args.first; |
| if (arg is FunctionExpression) { |
| if (arg.parameters.parameters.length != 1) return; |
| |
| final body = arg.body; |
| Expression expression; |
| if (body is BlockFunctionBody) { |
| final statements = body.block.statements; |
| if (statements.length != 1) return; |
| final statement = body.block.statements.first; |
| if (statement is ReturnStatement) { |
| expression = statement.expression; |
| } |
| } else if (body is ExpressionFunctionBody) { |
| expression = body.expression; |
| } |
| expression = expression?.unParenthesized; |
| if (expression is IsExpression && expression.notOperator == null) { |
| final target = expression.expression; |
| if (target is SimpleIdentifier && |
| target.name == arg.parameters.parameters.first.identifier.name) { |
| rule.reportLint(node.methodName); |
| } |
| } |
| } |
| } |
| } |