| // 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 'package:analyzer/dart/element/element.dart'; |
| import 'package:linter/src/analyzer.dart'; |
| |
| const _desc = r'Put @required named parameters first.'; |
| |
| const _details = r''' |
| |
| **DO** specify `@required` on named parameter before other named parameters. |
| |
| **GOOD:** |
| ``` |
| m({@required a, b, c}) ; |
| ``` |
| |
| **BAD:** |
| ``` |
| m({b, c, @required a}) ; |
| ``` |
| |
| '''; |
| |
| /// The name of `meta` library, used to define analysis annotations. |
| String _META_LIB_NAME = 'meta'; |
| |
| /// The name of the top-level variable used to mark a required named parameter. |
| String _REQUIRED_VAR_NAME = 'required'; |
| |
| bool _isRequired(Element element) => |
| element is PropertyAccessorElement && |
| element.name == _REQUIRED_VAR_NAME && |
| element.library?.name == _META_LIB_NAME; |
| |
| class AlwaysPutRequiredNamedParametersFirst extends LintRule |
| implements NodeLintRule { |
| AlwaysPutRequiredNamedParametersFirst() |
| : super( |
| name: 'always_put_required_named_parameters_first', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors(NodeLintRegistry registry) { |
| final visitor = new _Visitor(this); |
| registry.addFormalParameterList(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitFormalParameterList(FormalParameterList node) { |
| bool nonRequiredSeen = false; |
| for (DefaultFormalParameter param |
| in node.parameters.where((p) => p.isNamed)) { |
| if (param.metadata.any((a) => _isRequired(a.element))) { |
| if (nonRequiredSeen) { |
| rule.reportLintForToken(param.identifier.token); |
| } |
| } else { |
| nonRequiredSeen = true; |
| } |
| } |
| } |
| } |