Add ability to look up type parameters that are associated with ClassEntities with the element envi…

pkg/compiler/lib/src/common_elements.dart

 // Copyright (c) 2014, 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.
 
 // TODO(sigmund): rename and move to common/elements.dart
 library dart2js.type_system;
 
 import 'common.dart';
 import 'common/names.dart' show Identifiers, Uris;
 import 'constants/values.dart';
@@ skipping 1330 matching lines @@
 
   /// Returns the type of [function].
   FunctionType getFunctionType(FunctionEntity function);
 
   /// Returns the type of [field].
   DartType getFieldType(FieldEntity field);
 
   /// Returns the type of the [local] function.
   FunctionType getLocalFunctionType(Local local);
 
+  /// Returns the set of type parameters associated with a given class entity.
+  /// For example, for a class Foo, declared like this:
+  ///
+  ///     class Foo<A, B>{}
+  ///
+  /// getTypeVariables would return a list containing the [DartType]s
+  /// corresponding to A and B.
+  List<DartType> getTypeVariables(ClassEntity cls);

[Johnni Winther, 2017/09/04 06:59:56]

[getClassTypeVariables] is probably better since methods can also have type
variables.

[Emily Fortuna, 2017/09/05 17:13:31]

Done.

+
   /// Gets the constant value of [field], or `null` if [field] is non-const.
   ConstantExpression getFieldConstant(FieldEntity field);
 
   /// Returns the 'unaliased' type of [type]. For typedefs this is the function
   /// type it is an alias of, for other types it is the type itself.
   ///
   /// Use this during resolution to ensure that the alias has been computed.
   // TODO(johnniwinther): Remove this when the resolver is removed.
   DartType getUnaliasedType(DartType type);
 
@@ skipping 10 matching lines @@
   /// Returns the metadata constants declared on [typedef].
   Iterable<ConstantValue> getTypedefMetadata(TypedefEntity typedef);
 
   /// Returns the metadata constants declared on [member].
   Iterable<ConstantValue> getMemberMetadata(MemberEntity member,
       {bool includeParameterMetadata: false});
 
   /// Returns the function type that is an alias of a [typedef].
   FunctionType getFunctionTypeOfTypedef(TypedefEntity typedef);
 }