| // Copyright (c) 2021, 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/analysis/features.dart'; |
| import 'package:analyzer/dart/ast/ast.dart'; |
| import 'package:analyzer/dart/ast/token.dart'; |
| import 'package:analyzer/dart/ast/visitor.dart'; |
| import 'package:analyzer/dart/element/type.dart'; |
| |
| import '../analyzer.dart'; |
| |
| const _desc = r'Use if-null operators to convert nulls to bools.'; |
| |
| const _details = r''' |
| |
| Use if-null operators to convert nulls to bools. |
| |
| **BAD:** |
| ```dart |
| if (nullableBool == true) { |
| } |
| if (nullableBool != false) { |
| } |
| ``` |
| |
| **GOOD:** |
| ```dart |
| if (nullableBool ?? false) { |
| } |
| if (nullableBool ?? true) { |
| } |
| ``` |
| |
| '''; |
| |
| class UseIfNullToConvertNullsToBools extends LintRule implements NodeLintRule { |
| UseIfNullToConvertNullsToBools() |
| : super( |
| name: 'use_if_null_to_convert_nulls_to_bools', |
| description: _desc, |
| details: _details, |
| group: Group.style, |
| ); |
| |
| @override |
| void registerNodeProcessors( |
| NodeLintRegistry registry, LinterContext context) { |
| if (!context.isEnabled(Feature.non_nullable)) return; |
| |
| var visitor = _Visitor(this, context); |
| registry.addBinaryExpression(this, visitor); |
| } |
| } |
| |
| class _Visitor extends SimpleAstVisitor<void> { |
| final LintRule rule; |
| final LinterContext context; |
| |
| _Visitor(this.rule, this.context); |
| |
| @override |
| void visitBinaryExpression(BinaryExpression node) { |
| var type = node.leftOperand.staticType; |
| var right = node.rightOperand; |
| if (node.operator.type == TokenType.EQ_EQ && |
| isNullableBool(type) && |
| right is BooleanLiteral && |
| right.value) { |
| rule.reportLint(node); |
| } |
| if (node.operator.type == TokenType.BANG_EQ && |
| isNullableBool(type) && |
| right is BooleanLiteral && |
| !right.value) { |
| rule.reportLint(node); |
| } |
| } |
| |
| bool isNullableBool(DartType? type) => |
| type != null && |
| type.isDartCoreBool && |
| context.typeSystem.isNullable(type); |
| } |