Add DartType.alias{Element,Arguments} and class TypeAliasElement
First step in implementing non-function type aliases in the analyzer:
Just add the new back-references in types, such that they can refer to
a type alias which was used to obtain the type, if any.
Next step: Preserve the aliasElement and aliasArguments in summaries,
next again: Create `TypeAliasElementImpl` and ensure that the parser
can create them.
Change-Id: I1bfbc2c3893e32c5b1826552361a0238aa2b4058
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/169380
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Erik Ernst <eernst@google.com>
diff --git a/pkg/analyzer/lib/dart/element/element.dart b/pkg/analyzer/lib/dart/element/element.dart
index 2656b09..4e47272 100644
--- a/pkg/analyzer/lib/dart/element/element.dart
+++ b/pkg/analyzer/lib/dart/element/element.dart
@@ -1155,24 +1155,20 @@
/// A function type alias (`typedef`).
///
+/// This class models a type alias whose body specifies a function type, as
+/// is the only possible kind of type alias before the generalization that
+/// allows the body to be an arbitrary type.
+///
+/// This class will be deprecated and [TypeAliasElement] will replace it
+/// when non-function type aliases are enabled by default.
+///
/// Clients may not extend, implement or mix-in this class.
-abstract class FunctionTypeAliasElement
- implements TypeParameterizedElement, TypeDefiningElement {
- @override
- CompilationUnitElement get enclosingElement;
-
+abstract class FunctionTypeAliasElement implements TypeAliasElement {
/// Return the generic function type element representing the generic function
/// type on the right side of the equals.
GenericFunctionTypeElement get function;
- /// Produces the function type resulting from instantiating this typedef with
- /// the given [typeArguments] and [nullabilitySuffix].
- ///
- /// Note that this always instantiates the typedef itself, so for a
- /// [FunctionTypeAliasElement] the returned [FunctionType] might still be a
- /// generic function, with type formals. For example, if the typedef is:
- /// typedef F<T> = void Function<U>(T, U);
- /// then `F<int>` will produce `void Function<U>(int, U)`.
+ @override
FunctionType instantiate({
@required List<DartType> typeArguments,
@required NullabilitySuffix nullabilitySuffix,
@@ -1664,6 +1660,28 @@
bool get isExternal;
}
+/// A type alias (`typedef`).
+///
+/// Clients may not extend, implement or mix-in this class.
+abstract class TypeAliasElement
+ implements TypeParameterizedElement, TypeDefiningElement {
+ @override
+ CompilationUnitElement get enclosingElement;
+
+ /// Produces the type resulting from instantiating this typedef with the given
+ /// [typeArguments] and [nullabilitySuffix].
+ ///
+ /// Note that this always instantiates the typedef itself, so for a
+ /// [TypeAliasElement] the returned [DartType] might still be a generic
+ /// type, with type formals. For example, if the typedef is:
+ /// typedef F<T> = void Function<U>(T, U);
+ /// then `F<int>` will produce `void Function<U>(int, U)`.
+ DartType instantiate({
+ @required List<DartType> typeArguments,
+ @required NullabilitySuffix nullabilitySuffix,
+ });
+}
+
/// An element that defines a type.
///
/// Clients may not extend, implement or mix-in this class.
diff --git a/pkg/analyzer/lib/dart/element/type.dart b/pkg/analyzer/lib/dart/element/type.dart
index 326b7a8..e7c04af 100644
--- a/pkg/analyzer/lib/dart/element/type.dart
+++ b/pkg/analyzer/lib/dart/element/type.dart
@@ -29,6 +29,14 @@
///
/// Clients may not extend, implement or mix-in this class.
abstract class DartType {
+ /// If this type is an instantiation of a type alias, return the type
+ /// arguments used for the instantiation. Otherwise return `null`.
+ List<DartType> get aliasArguments;
+
+ /// If this type is an instantiation of a type alias, return it.
+ /// Otherwise return `null`.
+ TypeAliasElement get aliasElement;
+
/// Return the name of this type as it should appear when presented to users
/// in contexts such as error messages.
///
diff --git a/pkg/analyzer/lib/src/dart/element/type.dart b/pkg/analyzer/lib/src/dart/element/type.dart
index f0be482..20211b6 100644
--- a/pkg/analyzer/lib/src/dart/element/type.dart
+++ b/pkg/analyzer/lib/src/dart/element/type.dart
@@ -1602,12 +1602,18 @@
/// The abstract class `TypeImpl` implements the behavior common to objects
/// representing the declared type of elements in the element model.
abstract class TypeImpl implements DartType {
+ @override
+ final List<DartType> aliasArguments;
+
+ @override
+ final TypeAliasElement aliasElement;
+
/// The element representing the declaration of this type, or `null` if the
/// type has not, or cannot, be associated with an element.
final Element _element;
/// Initialize a newly created type to be declared by the given [element].
- TypeImpl(this._element);
+ TypeImpl(this._element, {this.aliasElement, this.aliasArguments});
@deprecated
@override
