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Extract logic from DecoratedType.forElement into a new class, AlreadyMigratedCodeDecorator.
I plan to add unit tests for AlreadyMigratedCodeDecorator in a follow-up CL (I can't add them now because I need to refactor some of the unit tests to avoid code duplication, and that refactoring depends on this CL). Change-Id: Id137f7b003df33306d894fc8771963173757bf45 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/112580 Commit-Queue: Paul Berry <paulberry@google.com> Reviewed-by: Mike Fairhurst <mfairhurst@google.com> Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
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‎pkg/nnbd_migration/lib/src/already_migrated_code_decorator.dart

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@@ -0,0 +1,66 @@
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// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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import 'package:analyzer/dart/element/type.dart';
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import 'package:analyzer/src/dart/element/type.dart';
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import 'package:nnbd_migration/src/decorated_type.dart';
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import 'package:nnbd_migration/src/nullability_node.dart';
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/// This class transforms ordinary [DartType]s into their corresponding
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/// [DecoratedType]s, assuming the [DartType]s come from code that has already
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/// been migrated to NNBD.
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class AlreadyMigratedCodeDecorator {
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final NullabilityGraph _graph;
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AlreadyMigratedCodeDecorator(this._graph);
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/// Transforms [type], which should have come from code that has already been
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/// migrated to NNBD, into the corresponding [DecoratedType].
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DecoratedType decorate(DartType type) {
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if (type.isVoid || type.isDynamic) {
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return DecoratedType(type, _graph.always);
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}
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var nullabilitySuffix = (type as TypeImpl).nullabilitySuffix;
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if (nullabilitySuffix == NullabilitySuffix.question) {
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// TODO(paulberry): add support for depending on already-migrated packages
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// containing nullable types.
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throw UnimplementedError(
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'Migration depends on an already-migrated nullable type');
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} else {
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// Currently, all types passed to this method have nullability suffix `star`
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// because (a) we don't yet have a migrated SDK, and (b) we haven't added
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// support to the migrator for analyzing packages that have already been
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// migrated with NNBD enabled.
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// TODO(paulberry): fix this assertion when things change.
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assert(nullabilitySuffix == NullabilitySuffix.star);
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}
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if (type is FunctionType) {
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var positionalParameters = <DecoratedType>[];
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var namedParameters = <String, DecoratedType>{};
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for (var parameter in type.parameters) {
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if (parameter.isPositional) {
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positionalParameters.add(decorate(parameter.type));
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} else {
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namedParameters[parameter.name] = decorate(parameter.type);
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}
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}
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return DecoratedType(type, _graph.never,
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returnType: decorate(type.returnType),
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namedParameters: namedParameters,
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positionalParameters: positionalParameters);
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} else if (type is InterfaceType) {
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if (type.typeParameters.isNotEmpty) {
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// TODO(paulberry)
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throw UnimplementedError('Decorating ${type.displayName}');
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}
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return DecoratedType(type, _graph.never);
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} else if (type is TypeParameterType) {
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return DecoratedType(type, _graph.never);
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} else {
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// TODO(paulberry)
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throw UnimplementedError(
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'Unable to decorate already-migrated type $type');
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}
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}
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}

‎pkg/nnbd_migration/lib/src/decorated_type.dart

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Original file line numberDiff line numberDiff line change
@@ -83,68 +83,6 @@ class DecoratedType {
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}());
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}
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/// Creates a [DecoratedType] corresponding to the given [element], which is
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/// presumed to have come from code that is already migrated.
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factory DecoratedType.forElement(Element element, NullabilityGraph graph) {
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DecoratedType decorate(DartType type) {
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if (type.isVoid || type.isDynamic) {
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return DecoratedType(type, graph.always);
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}
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assert((type as TypeImpl).nullabilitySuffix ==
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NullabilitySuffix.star); // TODO(paulberry)
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if (type is FunctionType) {
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var positionalParameters = <DecoratedType>[];
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var namedParameters = <String, DecoratedType>{};
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for (var parameter in type.parameters) {
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if (parameter.isPositional) {
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positionalParameters.add(decorate(parameter.type));
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} else {
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namedParameters[parameter.name] = decorate(parameter.type);
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}
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}
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return DecoratedType(type, graph.never,
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returnType: decorate(type.returnType),
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namedParameters: namedParameters,
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positionalParameters: positionalParameters);
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} else if (type is InterfaceType) {
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if (type.typeParameters.isNotEmpty) {
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// TODO(paulberry)
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throw UnimplementedError('Decorating ${type.displayName}');
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}
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return DecoratedType(type, graph.never);
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} else if (type is TypeParameterType) {
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return DecoratedType(type, graph.never);
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} else {
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throw type.runtimeType; // TODO(paulberry)
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}
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}
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// Sanity check:
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// Ensure the element is not from a library that is being migrated.
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// If this assertion fires, it probably means that the NodeBuilder failed to
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// generate the appropriate decorated type for the element when it was
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// visiting the source file.
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if (graph.isBeingMigrated(element.source)) {
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throw 'Internal Error: DecorateType.forElement should not be called'
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' for elements being migrated: ${element.runtimeType} :: $element';
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}
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DecoratedType decoratedType;
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if (element is ExecutableElement) {
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decoratedType = decorate(element.type);
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} else if (element is TopLevelVariableElement) {
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decoratedType = decorate(element.type);
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} else if (element is TypeParameterElement) {
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// By convention, type parameter elements are decorated with the type of
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// their bounds.
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decoratedType = decorate(element.bound ?? DynamicTypeImpl.instance);
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} else {
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// TODO(paulberry)
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throw UnimplementedError('Decorating ${element.runtimeType}');
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}
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return decoratedType;
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}
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/// Creates a decorated type corresponding to [type], with fresh nullability
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/// nodes everywhere that don't correspond to any source location. These
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/// nodes can later be unioned with other nodes.

‎pkg/nnbd_migration/lib/src/variables.dart

Lines changed: 24 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,9 @@
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import 'package:analyzer/dart/ast/ast.dart';
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import 'package:analyzer/dart/element/element.dart';
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import 'package:analyzer/src/dart/element/handle.dart';
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import 'package:analyzer/src/dart/element/type.dart';
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import 'package:analyzer/src/generated/source.dart';
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import 'package:nnbd_migration/src/already_migrated_code_decorator.dart';
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import 'package:nnbd_migration/src/conditional_discard.dart';
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import 'package:nnbd_migration/src/decorated_type.dart';
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import 'package:nnbd_migration/src/expression_checks.dart';
@@ -26,7 +28,10 @@ class Variables implements VariableRecorder, VariableRepository {
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final _potentialModifications = <Source, List<PotentialModification>>{};
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Variables(this._graph);
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final AlreadyMigratedCodeDecorator _alreadyMigratedCodeDecorator;
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Variables(this._graph)
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: _alreadyMigratedCodeDecorator = AlreadyMigratedCodeDecorator(_graph);
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@override
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Map<ClassElement, DecoratedType> decoratedDirectSupertypes(
@@ -169,12 +174,29 @@ class Variables implements VariableRecorder, VariableRepository {
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(_potentialModifications[source] ??= []).add(potentialModification);
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}
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/// Creates a decorated type for the given [element], which should come from
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/// an already-migrated library (or the SDK).
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DecoratedType _createDecoratedElementType(Element element) {
173180
if (_graph.isBeingMigrated(element.library.source)) {
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throw StateError('A decorated type for $element should have been stored '
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'by the NodeBuilder via recordDecoratedElementType');
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}
177-
return DecoratedType.forElement(element, _graph);
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DecoratedType decoratedType;
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if (element is ExecutableElement) {
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decoratedType = _alreadyMigratedCodeDecorator.decorate(element.type);
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} else if (element is TopLevelVariableElement) {
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decoratedType = _alreadyMigratedCodeDecorator.decorate(element.type);
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} else if (element is TypeParameterElement) {
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// By convention, type parameter elements are decorated with the type of
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// their bounds.
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decoratedType = _alreadyMigratedCodeDecorator
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.decorate(element.bound ?? DynamicTypeImpl.instance);
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} else {
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// TODO(paulberry)
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throw UnimplementedError('Decorating ${element.runtimeType}');
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}
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return decoratedType;
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}
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/// Creates an entry [_decoratedDirectSupertypes] for an already-migrated

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