Improve type test and type equality for generics (issue 15148).

runtime/vm/object.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 1169 matching lines @@
 
 
 // AbstractTypeArguments is an abstract superclass.
 // Subclasses of AbstractTypeArguments are TypeArguments and
 // InstantiatedTypeArguments.
 class AbstractTypeArguments : public Object {
  public:
   // Returns true if all types of this vector are finalized.
   virtual bool IsFinalized() const { return true; }
 
-  // Returns true if both arguments represent vectors of equal types.
-  static bool AreEqual(const AbstractTypeArguments& arguments,
-                       const AbstractTypeArguments& other_arguments);
-
   // Return 'this' if this type argument vector is instantiated, i.e. if it does
   // not refer to type parameters. Otherwise, return a new type argument vector
   // where each reference to a type parameter is replaced with the corresponding
   // type of the instantiator type argument vector.
   // If bound_error is not NULL, it may be set to reflect a bound error.
   virtual RawAbstractTypeArguments* InstantiateFrom(
       const AbstractTypeArguments& instantiator_type_arguments,
       Error* bound_error) const;
 
   // Do not clone InstantiatedTypeArguments or null vectors, since they are
   // considered finalized.
   virtual RawAbstractTypeArguments* CloneUnfinalized() const {
     return this->raw();
   }
 
   // Do not canonicalize InstantiatedTypeArguments or null vectors.
   virtual RawAbstractTypeArguments* Canonicalize() const { return this->raw(); }
 
   // The name of this type argument vector, e.g. "<T, dynamic, List<T>, Smi>".
   virtual RawString* Name() const {
     return SubvectorName(0, Length(), kInternalName);
   }
 
   // The name of this type argument vector, e.g. "<T, dynamic, List<T>, int>".
   // Names of internal classes are mapped to their public interfaces.
   virtual RawString* UserVisibleName() const {
     return SubvectorName(0, Length(), kUserVisibleName);
   }
 
-  // Check if this type argument vector consists solely of DynamicType,
-  // considering only a prefix of length 'len'.
-  bool IsRaw(intptr_t len) const {
-    return IsDynamicTypes(false, len);
+  // Check if the subvector of length 'len' starting at 'from_index' of this
+  // type argument vector consists solely of DynamicType.
+  bool IsRaw(intptr_t from_index, intptr_t len) const {
+    return IsDynamicTypes(false, from_index, len);
   }
 
   // Check if this type argument vector would consist solely of DynamicType if
   // it was instantiated from a raw (null) instantiator, i.e. consider each type
   // parameter as it would be first instantiated from a vector of dynamic types.
   // Consider only a prefix of length 'len'.
   bool IsRawInstantiatedRaw(intptr_t len) const {
-    return IsDynamicTypes(true, len);
+    return IsDynamicTypes(true, 0, len);
   }
 
-  // Check the subtype relationship, considering only a prefix of length 'len'.
+  // Check the subtype relationship, considering only a subvector of length
+  // 'len' starting at 'from_index'.
   bool IsSubtypeOf(const AbstractTypeArguments& other,
+                   intptr_t from_index,
                    intptr_t len,
                    Error* bound_error) const {
-    return TypeTest(kIsSubtypeOf, other, len, bound_error);
+    return TypeTest(kIsSubtypeOf, other, from_index, len, bound_error);
   }
 
-  // Check the 'more specific' relationship, considering only a prefix of
-  // length 'len'.
+  // Check the 'more specific' relationship, considering only a subvector of
+  // length 'len' starting at 'from_index'.
   bool IsMoreSpecificThan(const AbstractTypeArguments& other,
+                          intptr_t from_index,
                           intptr_t len,
                           Error* bound_error) const {
-    return TypeTest(kIsMoreSpecificThan, other, len, bound_error);
+    return TypeTest(kIsMoreSpecificThan, other, from_index, len, bound_error);
   }
 
+  // Check if the vectors are equal.
   bool Equals(const AbstractTypeArguments& other) const;
 
   // UNREACHABLEs as AbstractTypeArguments is an abstract class.
   virtual intptr_t Length() const;
   virtual RawAbstractType* TypeAt(intptr_t index) const;
   virtual void SetTypeAt(intptr_t index, const AbstractType& value) const;
   virtual bool IsResolved() const;
   virtual bool IsInstantiated() const;
   virtual bool IsUninstantiatedIdentity() const;
   virtual bool CanShareInstantiatorTypeArguments(
       const Class& instantiator_class) const;
   virtual bool IsBounded() const;
 
   virtual intptr_t Hash() const;
 
  private:
-  // Check if this type argument vector consists solely of DynamicType,
-  // considering only a prefix of length 'len'.
+  // Check if the subvector of length 'len' starting at 'from_index' of this
+  // type argument vector consists solely of DynamicType.
   // If raw_instantiated is true, consider each type parameter to be first
   // instantiated from a vector of dynamic types.
-  bool IsDynamicTypes(bool raw_instantiated, intptr_t len) const;
+  bool IsDynamicTypes(bool raw_instantiated,
+                      intptr_t from_index,
+                      intptr_t len) const;
 
   // Check the subtype or 'more specific' relationship, considering only a
-  // prefix of length 'len'.
+  // subvector of length 'len' starting at 'from_index'.
   bool TypeTest(TypeTestKind test_kind,
                 const AbstractTypeArguments& other,
+                intptr_t from_index,
                 intptr_t len,
                 Error* bound_error) const;
 
   // Return the internal or public name of a subvector of this type argument
   // vector, e.g. "<T, dynamic, List<T>, int>".
   RawString* SubvectorName(intptr_t from_index,
                            intptr_t len,
                            NameVisibility name_visibility) const;
 
  protected:
@@ skipping 5138 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_