| // 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. |
| |
| library linter.src.rules.prefer_constructors_instead_of_static_methods; |
| |
| 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'Prefer defining constructors instead of static methods to create instances.'; |
| |
| const _details = r''' |
| |
| **PREFER** defining constructors instead of static methods to create instances. |
| |
| **BAD:** |
| ``` |
| class Point { |
| num x, y; |
| Point(this.x, this.y); |
| static Point polar(num theta, num radius) { |
| return new Point(radius * math.cos(theta), |
| radius * math.sin(theta)); |
| } |
| } |
| ``` |
| |
| **GOOD:** |
| ``` |
| class Point { |
| num x, y; |
| Point(this.x, this.y); |
| Point.polar(num theta, num radius) |
| : x = radius * math.cos(theta), |
| y = radius * math.sin(theta); |
| } |
| ``` |
| |
| '''; |
| |
| bool _hasNewInvocation(DartType returnType, FunctionBody body) { |
| bool _isInstanceCreationExpression(AstNode node) { |
| return node is InstanceCreationExpression && node.bestType == returnType; |
| } |
| |
| return DartTypeUtilities |
| .traverseNodesInDFS(body) |
| .any(_isInstanceCreationExpression); |
| } |
| |
| class PreferConstructorsInsteadOfStaticMethods extends LintRule { |
| _Visitor _visitor; |
| PreferConstructorsInsteadOfStaticMethods() |
| : super( |
| name: 'prefer_constructors_instead_of_static_methods', |
| description: _desc, |
| details: _details, |
| group: Group.style) { |
| _visitor = new _Visitor(this); |
| } |
| |
| @override |
| AstVisitor getVisitor() => _visitor; |
| } |
| |
| class _Visitor extends SimpleAstVisitor { |
| final LintRule rule; |
| _Visitor(this.rule); |
| |
| @override |
| visitMethodDeclaration(MethodDeclaration node) { |
| final returnType = node.returnType?.type; |
| if (node.isStatic && |
| returnType == (node.parent as ClassDeclaration).element.type && |
| _hasNewInvocation(returnType, node.body)) { |
| rule.reportLint(node.name); |
| } |
| } |
| } |