| // Copyright (c) 2019, 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/element/type.dart'; |
| import 'package:analyzer/error/listener.dart'; |
| import 'package:analyzer/src/dart/element/type.dart'; |
| import 'package:analyzer/src/error/codes.dart'; |
| import 'package:analyzer/src/generated/resolver.dart'; |
| import 'package:meta/meta.dart'; |
| |
| /// Helper for checking potentially nullable dereferences. |
| class NullableDereferenceVerifier { |
| final TypeSystemImpl _typeSystem; |
| final ErrorReporter _errorReporter; |
| |
| NullableDereferenceVerifier({ |
| @required TypeSystemImpl typeSystem, |
| @required ErrorReporter errorReporter, |
| }) : _typeSystem = typeSystem, |
| _errorReporter = errorReporter; |
| |
| bool expression(Expression expression, {DartType type}) { |
| if (!_typeSystem.isNonNullableByDefault) { |
| return false; |
| } |
| |
| type ??= expression.staticType; |
| return _check(expression, type); |
| } |
| |
| void report(AstNode errorNode, DartType receiverType) { |
| var errorCode = receiverType == _typeSystem.typeProvider.nullType |
| ? StaticWarningCode.INVALID_USE_OF_NULL_VALUE |
| : StaticWarningCode.UNCHECKED_USE_OF_NULLABLE_VALUE; |
| _errorReporter.reportErrorForNode(errorCode, errorNode); |
| } |
| |
| /// If the [receiverType] is potentially nullable, report it. |
| /// |
| /// The [errorNode] is usually the receiver of the invocation, but if the |
| /// receiver is the implicit `this`, the name of the invocation. |
| bool _check(AstNode errorNode, DartType receiverType) { |
| if (identical(receiverType, DynamicTypeImpl.instance) || |
| !_typeSystem.isPotentiallyNullable(receiverType)) { |
| return false; |
| } |
| |
| report(errorNode, receiverType); |
| return true; |
| } |
| } |