| // Copyright (c) 2020, 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:analyzer/dart/element/type.dart'; |
| |
| import '../analyzer.dart'; |
| import '../extensions.dart'; |
| |
| const _desc = r'Define case clauses for all constants in enum-like classes.'; |
| |
| const _details = r''' |
| Switching on instances of enum-like classes should be exhaustive. |
| |
| Enum-like classes are defined as concrete (non-abstract) classes that have: |
| * only private non-factory constructors |
| * two or more static const fields whose type is the enclosing class and |
| * no subclasses of the class in the defining library |
| |
| **DO** define case clauses for all constants in enum-like classes. |
| |
| **BAD:** |
| ```dart |
| class EnumLike { |
| final int i; |
| const EnumLike._(this.i); |
| |
| static const e = EnumLike._(1); |
| static const f = EnumLike._(2); |
| static const g = EnumLike._(3); |
| } |
| |
| void bad(EnumLike e) { |
| // Missing case. |
| switch(e) { // LINT |
| case EnumLike.e : |
| print('e'); |
| break; |
| case EnumLike.f : |
| print('f'); |
| break; |
| } |
| } |
| ``` |
| |
| **GOOD:** |
| ```dart |
| class EnumLike { |
| final int i; |
| const EnumLike._(this.i); |
| |
| static const e = EnumLike._(1); |
| static const f = EnumLike._(2); |
| static const g = EnumLike._(3); |
| } |
| |
| void ok(EnumLike e) { |
| // All cases covered. |
| switch(e) { // OK |
| case EnumLike.e : |
| print('e'); |
| break; |
| case EnumLike.f : |
| print('f'); |
| break; |
| case EnumLike.g : |
| print('g'); |
| break; |
| } |
| } |
| ``` |
| '''; |
| |
| class ExhaustiveCases extends LintRule { |
| ExhaustiveCases() |
| : super( |
| name: 'exhaustive_cases', |
| description: _desc, |
| details: _details, |
| group: Group.style); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| var visitor = _Visitor(this); |
| registry.addSwitchStatement(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor { |
| static const LintCode lintCode = LintCode( |
| 'exhaustive_cases', |
| "Missing case clause for '{0}'.", |
| correctionMessage: 'Try adding a case clause for the missing constant.', |
| ); |
| |
| final LintRule rule; |
| |
| _Visitor(this.rule); |
| |
| @override |
| void visitSwitchStatement(SwitchStatement statement) { |
| var expressionType = statement.expression.staticType; |
| if (expressionType is InterfaceType) { |
| var interfaceElement = expressionType.element2; |
| // Handled in analyzer. |
| if (interfaceElement is! ClassElement) { |
| return; |
| } |
| var enumDescription = interfaceElement.asEnumLikeClass; |
| if (enumDescription == null) { |
| return; |
| } |
| |
| var enumConstants = enumDescription.enumConstants; |
| for (var member in statement.members) { |
| if (member is SwitchCase) { |
| var expression = member.expression; |
| if (expression is Identifier) { |
| var element = expression.staticElement; |
| if (element is PropertyAccessorElement) { |
| enumConstants.remove(element.variable.computeConstantValue()); |
| } else if (element is VariableElement) { |
| enumConstants.remove(element.computeConstantValue()); |
| } |
| } else if (expression is PropertyAccess) { |
| var element = expression.propertyName.staticElement; |
| if (element is PropertyAccessorElement) { |
| enumConstants.remove(element.variable.computeConstantValue()); |
| } else if (element is VariableElement) { |
| enumConstants.remove(element.computeConstantValue()); |
| } |
| } |
| } |
| if (member is SwitchDefault) { |
| return; |
| } |
| } |
| |
| for (var constant in enumConstants.keys) { |
| // Use the same offset as MISSING_ENUM_CONSTANT_IN_SWITCH. |
| var offset = statement.offset; |
| var end = statement.rightParenthesis.end; |
| var elements = enumConstants[constant]!; |
| var preferredElement = elements.firstWhere( |
| (element) => !element.hasDeprecated, |
| orElse: () => elements.first); |
| rule.reportLintForOffset( |
| offset, |
| end - offset, |
| arguments: [preferredElement.name], |
| errorCode: lintCode, |
| ); |
| } |
| } |
| } |
| } |