| // Copyright (c) 2017, 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'Start the name of the method with to/_to or as/_as if applicable.'; |
| |
| const _details = r''' |
| |
| From the [design guide](https://www.dartlang.org/guides/language/effective-dart/design): |
| |
| **PREFER** naming a method to___() if it copies the object's state to a new object. |
| |
| **PREFER** naming a method as___() if it returns a different representation backed by the original object. |
| |
| **BAD:** |
| ``` |
| class Bar { |
| Foo myMethod() { |
| return Foo.from(this); |
| } |
| } |
| ``` |
| |
| **GOOD:** |
| ``` |
| class Bar { |
| Foo toFoo() { |
| return Foo.from(this); |
| } |
| } |
| ``` |
| |
| **GOOD:** |
| ``` |
| class Bar { |
| Foo asFoo() { |
| return Foo.from(this); |
| } |
| } |
| ``` |
| |
| '''; |
| |
| bool _beginsWithAsOrTo(String name) { |
| final regExp = RegExp(r'(to|as|_to|_as)[A-Z]', caseSensitive: true); |
| return regExp.matchAsPrefix(name) != null; |
| } |
| |
| bool _isVoid(TypeAnnotation returnType) => |
| returnType is TypeName && returnType.name.name == 'void'; |
| |
| class UseToAndAsIfApplicable extends LintRule implements NodeLintRule { |
| UseToAndAsIfApplicable() |
| : super( |
| name: 'use_to_and_as_if_applicable', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| final visitor = _Visitor(this); |
| registry.addMethodDeclaration(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitMethodDeclaration(MethodDeclaration node) { |
| if (!node.isGetter && |
| node.parameters.parameters.isEmpty && |
| !_isVoid(node.returnType) && |
| !_beginsWithAsOrTo(node.name.name) && |
| !DartTypeUtilities.hasInheritedMethod(node) && |
| _checkBody(node.body)) { |
| rule.reportLint(node.name); |
| } |
| } |
| |
| bool _checkBody(FunctionBody body) { |
| if (body is ExpressionFunctionBody) { |
| return _checkExpression(body.expression); |
| } else if (body is BlockFunctionBody && body.block.statements.length == 1) { |
| final statement = body.block.statements.first; |
| if (statement is ReturnStatement) { |
| return _checkExpression(statement.expression); |
| } |
| } |
| return false; |
| } |
| |
| bool _checkExpression(Expression rawExpression) { |
| final expression = rawExpression?.unParenthesized; |
| return expression is InstanceCreationExpression && |
| expression.argumentList.arguments.length == 1 && |
| expression.argumentList.arguments.first is ThisExpression; |
| } |
| } |