blob: 4a5d28eaa0545ea0c66022d8ddaef064ba6ec993 [file] [log] [blame]
// 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/ast/syntactic_entity.dart';
import 'package:analyzer/dart/ast/token.dart';
import 'package:analyzer/dart/element/type.dart';
import 'package:analyzer/diagnostic/diagnostic.dart';
import 'package:analyzer/error/error.dart';
import 'package:analyzer/error/listener.dart';
import 'package:analyzer/src/dart/ast/extensions.dart';
import 'package:analyzer/src/dart/element/type.dart';
import 'package:analyzer/src/dart/element/type_system.dart';
import 'package:analyzer/src/error/codes.dart';
import 'package:analyzer/src/generated/resolver.dart';
/// Helper for checking potentially nullable dereferences.
class NullableDereferenceVerifier {
final TypeSystemImpl _typeSystem;
final ErrorReporter _errorReporter;
/// The resolver driving this participant.
final ResolverVisitor _resolver;
NullableDereferenceVerifier({
required TypeSystemImpl typeSystem,
required ErrorReporter errorReporter,
required ResolverVisitor resolver,
}) : _typeSystem = typeSystem,
_errorReporter = errorReporter,
_resolver = resolver;
bool expression(ErrorCode errorCode, Expression expression,
{DartType? type}) {
if (!_typeSystem.isNonNullableByDefault) {
return false;
}
type ??= expression.typeOrThrow;
return _check(errorCode, expression, type);
}
void report(
ErrorCode errorCode, SyntacticEntity errorEntity, DartType receiverType,
{List<String> arguments = const <String>[],
List<DiagnosticMessage>? messages}) {
if (receiverType == _typeSystem.typeProvider.nullType) {
errorCode = CompileTimeErrorCode.INVALID_USE_OF_NULL_VALUE;
arguments = [];
}
if (errorEntity is AstNode) {
_errorReporter.reportErrorForNode(
errorCode, errorEntity, arguments, messages);
} else if (errorEntity is Token) {
_errorReporter.reportErrorForToken(
errorCode, errorEntity, arguments, messages);
} else {
throw StateError('Syntactic entity must be AstNode or Token to report.');
}
}
/// 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.
///
/// Returns whether [receiverType] was reported.
bool _check(
ErrorCode errorCode,
AstNode errorNode,
DartType receiverType,
) {
if (identical(receiverType, DynamicTypeImpl.instance) ||
!_typeSystem.isPotentiallyNullable(receiverType)) {
return false;
}
List<DiagnosticMessage>? messages;
if (errorNode is Expression) {
messages = _resolver.computeWhyNotPromotedMessages(
errorNode, _resolver.flowAnalysis.flow?.whyNotPromoted(errorNode)());
}
report(errorCode, errorNode, receiverType, messages: messages);
return true;
}
}