Remove signature classes from the VM.

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 923 matching lines @@
   virtual RawString* DictionaryName() const { return Name(); }
 
   RawScript* script() const { return raw_ptr()->script_; }
   void set_script(const Script& value) const;
 
   intptr_t token_pos() const { return raw_ptr()->token_pos_; }
   void set_token_pos(intptr_t value) const;
 
   intptr_t ComputeEndTokenPos() const;
 
-  // This class represents the signature class of a closure function if
-  // signature_function() is not null.
-  // The associated function may be a closure function (with code) or a
-  // signature function (without code) solely describing the result type and
-  // parameter types of the signature.
+  // This class represents a typedef if the signature function is not null.
   RawFunction* signature_function() const {
     return raw_ptr()->signature_function_;
   }
-  static intptr_t signature_function_offset() {
-    return OFFSET_OF(RawClass, signature_function_);
-  }
-
-  // Return the signature type of this signature class.
-  // For example, if this class represents a signature of the form
-  // 'F<T, R>(T, [b: B, c: C]) => R', then its signature type is a parameterized
-  // type with this class as the type class and type parameters 'T' and 'R'
-  // as its type argument vector.
-  // SignatureType is used as the type of formal parameters representing a
-  // function.
-  RawType* SignatureType() const;
+  void set_signature_function(const Function& value) const;
 
   // Return the Type with type parameters declared by this class filled in with
   // dynamic and type parameters declared in superclasses filled in as declared
   // in superclass clauses.
   RawAbstractType* RareType() const;
 
   // Return the Type whose arguments are the type parameters declared by this
   // class preceded by the type arguments declared for superclasses, etc.
   // e.g. given
   // class B<T, S>
@@ skipping 23 matching lines @@
   RawTypeParameter* LookupTypeParameter(const String& type_name) const;
 
   // The type argument vector is flattened and includes the type arguments of
   // the super class.
   intptr_t NumTypeArguments() const;
 
   // Return the number of type arguments that are specific to this class, i.e.
   // not overlapping with the type arguments of the super class of this class.
   intptr_t NumOwnTypeArguments() const;
 
+  // Return true if this class declares type parameters.
   bool IsGeneric() const;
 
   // If this class is parameterized, each instance has a type_arguments field.
   static const intptr_t kNoTypeArguments = -1;
   intptr_t type_arguments_field_offset() const {
     ASSERT(is_type_finalized() || is_prefinalized());
     if (raw_ptr()->type_arguments_field_offset_in_words_ == kNoTypeArguments) {
       return kNoTypeArguments;
     }
     return raw_ptr()->type_arguments_field_offset_in_words_ * kWordSize;
@@ skipping 70 matching lines @@
 
   // Check if this class represents the 'void' class.
   bool IsVoidClass() const { return id() == kVoidCid; }
 
   // Check if this class represents the 'Object' class.
   bool IsObjectClass() const { return id() == kInstanceCid; }
 
   // Check if this class represents the 'Function' class.
   bool IsFunctionClass() const;
 
-  // Check if this class represents a signature class.
-  bool IsSignatureClass() const {
+  // Check if this class represents the 'Closure' class.
+  bool IsClosureClass() const  { return id() == kClosureCid; }
+  static bool IsClosureClass(RawClass* cls) {
+    NoSafepointScope no_safepoint;
+    return cls->ptr()->id_ == kClosureCid;
+  }
+
+  // Check if this class represents a typedef class.
+  bool IsTypedefClass() const {
     return signature_function() != Object::null();
   }
-  static bool IsSignatureClass(RawClass* cls) {
-    return cls->ptr()->signature_function_ != Object::null();
-  }
+
   static bool IsInFullSnapshot(RawClass* cls) {
     NoSafepointScope no_safepoint;
     return cls->ptr()->library_->ptr()->is_in_fullsnapshot_;
   }
 
-  // Check if this class represents a canonical signature class, i.e. not an
-  // alias as defined in a typedef.
-  bool IsCanonicalSignatureClass() const;
-
   // Check the subtype relationship.
   bool IsSubtypeOf(const TypeArguments& type_arguments,
                    const Class& other,
                    const TypeArguments& other_type_arguments,
                    Error* bound_error,
                    Heap::Space space = Heap::kNew) const {
     return TypeTest(kIsSubtypeOf,
                     type_arguments,
                     other,
                     other_type_arguments,
@@ skipping 54 matching lines @@
   RawFunction* LookupGetterFunction(const String& name) const;
   RawFunction* LookupSetterFunction(const String& name) const;
   RawField* LookupInstanceField(const String& name) const;
   RawField* LookupStaticField(const String& name) const;
   RawField* LookupField(const String& name) const;
 
   RawLibraryPrefix* LookupLibraryPrefix(const String& name) const;
 
   void InsertCanonicalConstant(intptr_t index, const Instance& constant) const;
 
-  intptr_t FindCanonicalTypeIndex(const Type& needle) const;
-  RawType* CanonicalTypeFromIndex(intptr_t idx) const;
+  intptr_t FindCanonicalTypeIndex(const AbstractType& needle) const;
+  RawAbstractType* CanonicalTypeFromIndex(intptr_t idx) const;
 
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawClass));
   }
 
   bool is_implemented() const {
     return ImplementedBit::decode(raw_ptr()->state_bits_);
   }
   void set_is_implemented() const;
 
@@ skipping 128 matching lines @@
 
   // Allocate the raw TypedData classes.
   static RawClass* NewTypedDataClass(intptr_t class_id);
 
   // Allocate the raw TypedDataView classes.
   static RawClass* NewTypedDataViewClass(intptr_t class_id);
 
   // Allocate the raw ExternalTypedData classes.
   static RawClass* NewExternalTypedDataClass(intptr_t class_id);
 
-  // Allocate a class representing a function signature described by
-  // signature_function, which must be a closure function or a signature
-  // function.
-  // The class may be type parameterized unless the signature_function is in a
-  // static scope. In that case, the type parameters are copied from the owner
-  // class of signature_function.
-  // A null signature function may be passed in and patched later. See below.
-  static RawClass* NewSignatureClass(const String& name,
-                                     const Function& signature_function,
-                                     const Script& script,
-                                     intptr_t token_pos);
-
-  // Patch the signature function of a signature class allocated without it.
-  void PatchSignatureFunction(const Function& signature_function) const;
-
   // Register code that has used CHA for optimization.
   // TODO(srdjan): Also register kind of CHA optimization (e.g.: leaf class,
   // leaf method, ...).
   void RegisterCHACode(const Code& code);
 
   void DisableCHAOptimizedCode(const Class& subclass);
 
   RawArray* cha_codes() const { return raw_ptr()->cha_codes_; }
   void set_cha_codes(const Array& value) const;
 
@@ skipping 40 matching lines @@
       kFieldsMarkedNullableBit, 1> {};  // NOLINT
   class CycleFreeBit : public BitField<bool, kCycleFreeBit, 1> {};
   class EnumBit : public BitField<bool, kEnumBit, 1> {};
   class IsAllocatedBit : public BitField<bool, kIsAllocatedBit, 1> {};
 
   void set_name(const String& value) const;
   void set_pretty_name(const String& value) const;
   void set_user_name(const String& value) const;
   RawString* GeneratePrettyName() const;
   RawString* GenerateUserVisibleName() const;
-  void set_signature_function(const Function& value) const;
-  void set_signature_type(const AbstractType& value) const;
   void set_state_bits(intptr_t bits) const;
 
   void set_constants(const Array& value) const;
 
   void set_canonical_types(const Object& value) const;
   RawObject* canonical_types() const;
 
   RawArray* invocation_dispatcher_cache() const;
   void set_invocation_dispatcher_cache(const Array& cache) const;
   RawFunction* CreateInvocationDispatcher(const String& target_name,
@@ skipping 52 matching lines @@
       const Class& other,
       const TypeArguments& other_type_arguments,
       Error* bound_error,
       Heap::Space space);
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(Class, Object);
   friend class AbstractType;
   friend class Instance;
   friend class Object;
   friend class Type;
+  friend class FunctionType;
   friend class Intrinsifier;
   friend class Precompiler;
 };
 
 
 // Unresolved class is used for storing unresolved names which will be resolved
 // to a class after all classes have been loaded and finalized.
 class UnresolvedClass : public Object {
  public:
   RawLibraryPrefix* library_prefix() const {
@@ skipping 605 matching lines @@
   RawString* name() const { return raw_ptr()->name_; }
   RawString* PrettyName() const;
   RawString* UserVisibleName() const;
   RawString* QualifiedPrettyName() const;
   RawString* QualifiedUserVisibleName() const;
   const char* QualifiedUserVisibleNameCString() const;
   virtual RawString* DictionaryName() const { return name(); }
 
   RawString* GetSource() const;
 
+  // Return the type of this function's signature. It may not be canonical yet.
+  // For example, if this function has a signature of the form
+  // '(T, [b: B, c: C]) => R', where 'T' and 'R' are type parameters of the
+  // owner class of this function, then its signature type is a parameterized
+  // FunctionType with uninstantiated type arguments 'T' and 'R' as elements of
+  // its type argument vector.
+  RawFunctionType* SignatureType() const;
+
+  // Update the signature type (with a canonical version).
+  void SetSignatureType(const FunctionType& value) const;
+
   // Build a string of the form 'C<T, R>(T, {b: B, c: C}) => R' representing the
   // internal signature of the given function. In this example, T and R are
   // type parameters of class C, the owner of the function.
   RawString* Signature() const {
     const bool instantiate = false;
     return BuildSignature(instantiate, kInternalName, TypeArguments::Handle());
   }
 
   RawString* PrettySignature() const {
     const bool instantiate = false;
     return BuildSignature(
         instantiate, kPrettyName, TypeArguments::Handle());
   }
 
   // Build a string of the form '(T, {b: B, c: C}) => R' representing the
   // user visible signature of the given function. In this example, T and R are
-  // type parameters of class C, the owner of the function.
+  // type parameters of class C, the owner of the function, also called the
+  // scope class of the function type.
   // Implicit parameters are hidden, as well as the prefix denoting the
-  // signature class and its type parameters.
+  // scope class and its type parameters.
   RawString* UserVisibleSignature() const {
     const bool instantiate = false;
     return BuildSignature(
         instantiate, kUserVisibleName, TypeArguments::Handle());
   }
 
   // Build a string of the form '(A, {b: B, c: C}) => D' representing the
   // signature of the given function, where all generic types (e.g. '<T, R>' in
   // 'C<T, R>(T, {b: B, c: C}) => R') are instantiated using the given
   // instantiator type argument vector of a C instance (e.g. '<A, D>').
@@ skipping 72 matching lines @@
   bool HasBreakpoint() const;
 
   RawContextScope* context_scope() const;
   void set_context_scope(const ContextScope& value) const;
 
   RawField* LookupImplicitGetterSetterField() const;
 
   // Enclosing function of this local function.
   RawFunction* parent_function() const;
 
-  // Signature class of this closure function or signature function.
-  RawClass* signature_class() const;
-  void set_signature_class(const Class& value) const;
-
   void set_extracted_method_closure(const Function& function) const;
   RawFunction* extracted_method_closure() const;
 
   void set_saved_args_desc(const Array& array) const;
   RawArray* saved_args_desc() const;
 
   bool IsMethodExtractor() const {
     return kind() == RawFunction::kMethodExtractor;
   }
 
@@ skipping 251 matching lines @@
                           Error* bound_error,
                    Heap::Space space = Heap::kNew) const {
     return TypeTest(kIsMoreSpecificThan,
                     type_arguments,
                     other,
                     other_type_arguments,
                     bound_error,
                     space);
   }
 
+  // Check the subtype or 'more specific' relationship.
+  bool TypeTest(TypeTestKind test_kind,
+                const TypeArguments& type_arguments,
+                const Function& other,
+                const TypeArguments& other_type_arguments,
+                Error* bound_error,
+                Heap::Space space) const;
+
   // Returns true if this function represents an explicit getter function.
   bool IsGetterFunction() const {
     return kind() == RawFunction::kGetterFunction;
   }
 
   // Returns true if this function represents an implicit getter function.
   bool IsImplicitGetterFunction() const {
     return kind() == RawFunction::kImplicitGetter;
   }
 
@@ skipping 43 matching lines @@
 
   // Returns true if this function represents a local function.
   bool IsLocalFunction() const {
     return parent_function() != Function::null();
   }
 
   // Returns true if this function represents a signature function without code.
   bool IsSignatureFunction() const {
     return kind() == RawFunction::kSignatureFunction;
   }
+  static bool IsSignatureFunction(RawFunction* function) {
+    NoSafepointScope no_safepoint;
+    return KindBits::decode(function->ptr()->kind_tag_) ==
+        RawFunction::kSignatureFunction;
+  }
 
   bool IsAsyncFunction() const {
     return modifier() == RawFunction::kAsync;
   }
 
   bool IsAsyncClosure() const {
     return is_generated_body() &&
         Function::Handle(parent_function()).IsAsyncFunction();
   }
 
@@ skipping 35 matching lines @@
   static RawFunction* New(const String& name,
                           RawFunction::Kind kind,
                           bool is_static,
                           bool is_const,
                           bool is_abstract,
                           bool is_external,
                           bool is_native,
                           const Object& owner,
                           intptr_t token_pos);
 
-  // Allocates a new Function object representing a closure function, as well as
-  // a new associated Class object representing the signature class of the
-  // function.
-  // The function and the class share the same given name.
+  // Allocates a new Function object representing a closure function.
   static RawFunction* NewClosureFunction(const String& name,
                                          const Function& parent,
                                          intptr_t token_pos);
 
+  // Allocates a new Function object representing a signature function.
+  // The owner is the scope class of the function type.
+  static RawFunction* NewSignatureFunction(const Class& owner,
+                                           intptr_t token_pos);
+
   static RawFunction* NewEvalFunction(const Class& owner,
                                       const Script& script,
                                       bool is_static);
 
   RawFunction* CreateMethodExtractor(const String& getter_name) const;
   RawFunction* GetMethodExtractor(const String& getter_name) const;
 
   // Allocate new function object, clone values from this function. The
   // owner of the clone is new_owner.
   RawFunction* Clone(const Class& new_owner) const;
@@ skipping 135 matching lines @@
 
   void BuildSignatureParameters(
       bool instantiate,
       NameVisibility name_visibility,
       const TypeArguments& instantiator,
       GrowableHandlePtrArray<const String>* pieces) const;
   RawString* BuildSignature(bool instantiate,
                             NameVisibility name_visibility,
                             const TypeArguments& instantiator) const;
 
-  // Check the subtype or 'more specific' relationship.
-  bool TypeTest(TypeTestKind test_kind,
-                const TypeArguments& type_arguments,
-                const Function& other,
-                const TypeArguments& other_type_arguments,
-                Error* bound_error,
-                Heap::Space space) const;
-
   // Checks the type of the formal parameter at the given position for
   // subtyping or 'more specific' relationship between the type of this function
   // and the type of the other function.
   bool TestParameterType(TypeTestKind test_kind,
                          intptr_t parameter_position,
                          intptr_t other_parameter_position,
                          const TypeArguments& type_arguments,
                          const Function& other,
                          const TypeArguments& other_type_arguments,
                          Error* bound_error,
@@ skipping 16 matching lines @@
   }
 
  private:
   RawContextScope* context_scope() const { return raw_ptr()->context_scope_; }
   void set_context_scope(const ContextScope& value) const;
 
   // Enclosing function of this local function.
   RawFunction* parent_function() const { return raw_ptr()->parent_function_; }
   void set_parent_function(const Function& value) const;
 
-  // Signature class of this closure function or signature function.
-  RawClass* signature_class() const { return raw_ptr()->signature_class_; }
-  void set_signature_class(const Class& value) const;
+  // Signature type of this closure function.
+  RawFunctionType* signature_type() const { return raw_ptr()->signature_type_; }
+  void set_signature_type(const FunctionType& value) const;
 
   RawInstance* implicit_static_closure() const {
     return raw_ptr()->closure_;
   }
   void set_implicit_static_closure(const Instance& closure) const;
 
   static RawClosureData* New();
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(ClosureData, Object);
   friend class Class;
@@ skipping 1885 matching lines @@
   static inline RawObject* GetTargetFunction(const Array& array,
                                              intptr_t index);
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(MegamorphicCache, Object);
 };
 
 
 class SubtypeTestCache : public Object {
  public:
   enum Entries {
-    kInstanceClassId = 0,
+    kInstanceClassIdOrFunction = 0,
     kInstanceTypeArguments = 1,
     kInstantiatorTypeArguments = 2,
     kTestResult = 3,
     kTestEntryLength  = 4,
   };
 
   intptr_t NumberOfChecks() const;
-  void AddCheck(intptr_t class_id,
+  void AddCheck(const Object& instance_class_id_or_function,
                 const TypeArguments& instance_type_arguments,
                 const TypeArguments& instantiator_type_arguments,
                 const Bool& test_result) const;
   void GetCheck(intptr_t ix,
-                intptr_t* class_id,
+                Object* instance_class_id_or_function,
                 TypeArguments* instance_type_arguments,
                 TypeArguments* instantiator_type_arguments,
                 Bool* test_result) const;
 
   static RawSubtypeTestCache* New();
 
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawSubtypeTestCache));
   }
 
@@ skipping 202 matching lines @@
 
   RawObject* GetField(const Field& field) const {
     return *FieldAddr(field);
   }
 
   void SetField(const Field& field, const Object& value) const {
     field.RecordStore(value);
     StorePointer(FieldAddr(field), value.raw());
   }
 
-  RawType* GetType() const;
+  RawAbstractType* GetType() const;
 
   virtual RawTypeArguments* GetTypeArguments() const;
   virtual void SetTypeArguments(const TypeArguments& value) const;
 
   // Check if the type of this instance is a subtype of the given type.
   bool IsInstanceOf(const AbstractType& type,
                     const TypeArguments& type_instantiator,
                     Error* bound_error) const;
 
   bool IsValidNativeIndex(int index) const {
     return ((index >= 0) && (index < clazz()->ptr()->num_native_fields_));
   }
 
   intptr_t* NativeFieldsDataAddr() const;
   inline intptr_t GetNativeField(int index) const;
   inline void GetNativeFields(uint16_t num_fields,
                               intptr_t* field_values) const;
   void SetNativeFields(uint16_t num_fields,
                        const intptr_t* field_values) const;
 
   uint16_t NumNativeFields() const {
     return clazz()->ptr()->num_native_fields_;
   }
 
   void SetNativeField(int index, intptr_t value) const;
 
-  // Returns true if the instance is a closure object.
-  bool IsClosure() const;
-
   // If the instance is a callable object, i.e. a closure or the instance of a
   // class implementing a 'call' method, return true and set the function
   // (if not NULL) to call.
   bool IsCallable(Function* function) const;
 
   // Evaluate the given expression as if it appeared in an instance
   // method of this instance and return the resulting value, or an
   // error object if evaluating the expression fails. The method has
   // the formal parameters given in param_names, and is invoked with
   // the argument values given in param_values.
@@ skipping 106 matching lines @@
   FINAL_HEAP_OBJECT_IMPLEMENTATION(LibraryPrefix, Instance);
   friend class Class;
 };
 
 
 // AbstractType is an abstract superclass.
 // Subclasses of AbstractType are Type and TypeParameter.
 class AbstractType : public Instance {
  public:
   virtual bool IsFinalized() const;
+  virtual void SetIsFinalized() const;
   virtual bool IsBeingFinalized() const;
+  virtual void SetIsBeingFinalized() const;
   virtual bool IsMalformed() const;
   virtual bool IsMalbounded() const;
   virtual bool IsMalformedOrMalbounded() const;
   virtual RawLanguageError* error() const;
   virtual void set_error(const LanguageError& value) const;
   virtual bool IsResolved() const;
+  virtual void SetIsResolved() const;
   virtual bool HasResolvedTypeClass() const;
   virtual RawClass* type_class() const;
   virtual RawUnresolvedClass* unresolved_class() const;
   virtual RawTypeArguments* arguments() const;
+  virtual void set_arguments(const TypeArguments& value) const;
   virtual intptr_t token_pos() const;
   virtual bool IsInstantiated(TrailPtr trail = NULL) const;
   virtual bool CanonicalizeEquals(const Instance& other) const {
     return Equals(other);
   }
   virtual bool Equals(const Instance& other) const {
     return IsEquivalent(other);
   }
   virtual bool IsEquivalent(const Instance& other, TrailPtr trail = NULL) const;
   virtual bool IsRecursive() const;
@@ skipping 94 matching lines @@
 
   // Check if this type represents the 'num' type.
   bool IsNumberType() const;
 
   // Check if this type represents the '_Smi' type.
   bool IsSmiType() const;
 
   // Check if this type represents the 'String' type.
   bool IsStringType() const;
 
-  // Check if this type represents the 'Function' type.
-  bool IsFunctionType() const;
+  // Check if this type represents the Dart 'Function' type.
+  bool IsDartFunctionType() const;
 
   // Check the subtype relationship.
   bool IsSubtypeOf(const AbstractType& other,
                    Error* bound_error,
                    Heap::Space space = Heap::kNew) const {
     return TypeTest(kIsSubtypeOf, other, bound_error, space);
   }
 
   // Check the 'more specific' relationship.
   bool IsMoreSpecificThan(const AbstractType& other,
@@ skipping 31 matching lines @@
 class Type : public AbstractType {
  public:
   static intptr_t type_class_offset() {
     return OFFSET_OF(RawType, type_class_);
   }
   virtual bool IsFinalized() const {
     return
         (raw_ptr()->type_state_ == RawType::kFinalizedInstantiated) ||
         (raw_ptr()->type_state_ == RawType::kFinalizedUninstantiated);
   }
-  void SetIsFinalized() const;
-  void ResetIsFinalized() const;  // Ignore current state and set again.
+  virtual void SetIsFinalized() const;
   virtual bool IsBeingFinalized() const {
     return raw_ptr()->type_state_ == RawType::kBeingFinalized;
   }
-  void set_is_being_finalized() const;
+  virtual void SetIsBeingFinalized() const;
   virtual bool IsMalformed() const;
   virtual bool IsMalbounded() const;
   virtual bool IsMalformedOrMalbounded() const;
   virtual RawLanguageError* error() const { return raw_ptr()->error_; }
   virtual void set_error(const LanguageError& value) const;
   virtual bool IsResolved() const {
     return raw_ptr()->type_state_ >= RawType::kResolved;
   }
-  void set_is_resolved() const;
+  virtual void SetIsResolved() const;
   virtual bool HasResolvedTypeClass() const;  // Own type class resolved.
   virtual RawClass* type_class() const;
   void set_type_class(const Object& value) const;
   virtual RawUnresolvedClass* unresolved_class() const;
-  virtual RawTypeArguments* arguments() const;
-  void set_arguments(const TypeArguments& value) const;
+  virtual RawTypeArguments* arguments() const { return raw_ptr()->arguments_; }
+  virtual void set_arguments(const TypeArguments& value) const;
   virtual intptr_t token_pos() const { return raw_ptr()->token_pos_; }
   virtual bool IsInstantiated(TrailPtr trail = NULL) const;
   virtual bool IsEquivalent(const Instance& other, TrailPtr trail = NULL) const;
   virtual bool IsRecursive() const;
   virtual RawAbstractType* InstantiateFrom(
       const TypeArguments& instantiator_type_arguments,
       Error* bound_error,
       TrailPtr trail = NULL,
       Heap::Space space = Heap::kNew) const;
   virtual RawAbstractType* CloneUnfinalized() const;
@@ skipping 69 matching lines @@
   void set_type_state(int8_t state) const;
 
   static RawType* New(Heap::Space space = Heap::kOld);
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(Type, AbstractType);
   friend class Class;
   friend class TypeArguments;
 };
 
 
+// TODO(regis): FunctionType is very similar to Type. Instead of a separate
+// class FunctionType, we could consider an object of class Type as representing
+// a function type if it has a non-null function (signature) field.
+// In order to save space, we could reuse the error_ field? A malformed or
+// malbounded function type would lose its function reference, but the error
+// string would contain relevant info.
+
+// A FunctionType describes the signature of a function, i.e. the result type
+// and formal parameter types of the function, as well as the names of optional
+// named formal parameters.
+// If these types refer to type parameters of a class in scope, the function
+// type is generic. A generic function type may be instantiated by a type
+// argument vector.
+// Therefore, a FunctionType consists of a scope class, a type argument vector,
+// and a signature.
+// The scope class is either a generic class (or generic typedef) declaring the
+// type parameters referred to by the signature, or class _Closure in the
+// non-generic case (including the non-generic typedef case).
+// The type arguments specify an instantiation of the generic signature (null in
+// the non-generic case).
+// The signature is a reference to an actual closure function (kClosureFunction)
+// or to a signature function (kSignatureFunction).
+// Since typedefs cannot refer to themselves, directly or indirectly, a
+// FunctionType cannot be recursive. Only individual formal parameter types can.
+class FunctionType : public AbstractType {
+ public:
+  virtual bool IsFinalized() const {
+    return
+        (raw_ptr()->type_state_ == RawFunctionType::kFinalizedInstantiated) ||
+        (raw_ptr()->type_state_ == RawFunctionType::kFinalizedUninstantiated);
+  }
+  virtual void SetIsFinalized() const;
+  void ResetIsFinalized() const;  // Ignore current state and set again.
+  virtual bool IsBeingFinalized() const {
+    return raw_ptr()->type_state_ == RawFunctionType::kBeingFinalized;
+  }
+  virtual void SetIsBeingFinalized() const;
+  virtual bool IsMalformed() const;
+  virtual bool IsMalbounded() const;
+  virtual bool IsMalformedOrMalbounded() const;
+  virtual RawLanguageError* error() const { return raw_ptr()->error_; }
+  virtual void set_error(const LanguageError& value) const;
+  virtual bool IsResolved() const {
+    return raw_ptr()->type_state_ >= RawFunctionType::kResolved;
+  }
+  virtual void SetIsResolved() const;
+  // The scope class of a FunctionType is always resolved. It has no actual
+  // type class. Returning false is important for the type testers to work, e.g.
+  // IsDynamicType(), IsBoolType(), etc...
+  virtual bool HasResolvedTypeClass() const { return false; }
+  // Return scope_class from virtual type_class() to factorize finalization
+  // with Type, also a parameterized type.
+  virtual RawClass* type_class() const { return scope_class(); }
+  RawClass* scope_class() const { return raw_ptr()->scope_class_; }
+  void set_scope_class(const Class& value) const;
+  virtual RawTypeArguments* arguments() const { return raw_ptr()->arguments_; }
+  virtual void set_arguments(const TypeArguments& value) const;
+  RawFunction* signature() const { return raw_ptr()->signature_; }
+  virtual intptr_t token_pos() const { return raw_ptr()->token_pos_; }
+  virtual bool IsInstantiated(TrailPtr trail = NULL) const;
+  virtual bool IsEquivalent(const Instance& other, TrailPtr trail = NULL) const;
+  virtual bool IsRecursive() const;
+  virtual RawAbstractType* InstantiateFrom(
+      const TypeArguments& instantiator_type_arguments,
+      Error* malformed_error,
+      TrailPtr trail = NULL,
+      Heap::Space space = Heap::kNew) const;
+  virtual RawAbstractType* CloneUnfinalized() const;
+  virtual RawAbstractType* CloneUninstantiated(
+      const Class& new_owner,
+      TrailPtr trail = NULL) const;
+  virtual RawAbstractType* Canonicalize(TrailPtr trail = NULL) const;
+
+  virtual intptr_t Hash() const;
+
+  static intptr_t InstanceSize() {
+    return RoundedAllocationSize(sizeof(RawFunctionType));
+  }
+
+  static RawFunctionType* New(const Class& scope_class,
+                              const TypeArguments& arguments,
+                              const Function& signature,
+                              intptr_t token_pos,
+                              Heap::Space space = Heap::kOld);
+
+ private:
+  void set_signature(const Function& value) const;
+  void set_token_pos(intptr_t token_pos) const;
+  void set_type_state(int8_t state) const;
+
+  static RawFunctionType* New(Heap::Space space = Heap::kOld);
+
+  FINAL_HEAP_OBJECT_IMPLEMENTATION(FunctionType, AbstractType);
+  friend class Class;
+  friend class TypeArguments;
+};
+
+
 // A TypeRef is used to break cycles in the representation of recursive types.
 // Its only field is the recursive AbstractType it refers to.
 // Note that the cycle always involves type arguments.
 class TypeRef : public AbstractType {
  public:
   virtual bool IsFinalized() const {
     return AbstractType::Handle(type()).IsFinalized();
   }
   virtual bool IsBeingFinalized() const {
     return AbstractType::Handle(type()).IsBeingFinalized();
   }
   virtual bool IsMalformed() const {
     return AbstractType::Handle(type()).IsMalformed();
   }
   virtual bool IsMalbounded() const {
     return AbstractType::Handle(type()).IsMalbounded();
   }
   virtual bool IsMalformedOrMalbounded() const {
     return AbstractType::Handle(type()).IsMalformedOrMalbounded();
   }
   virtual bool IsResolved() const { return true; }
-  virtual bool HasResolvedTypeClass() const { return true; }
+  virtual bool HasResolvedTypeClass() const {
+    // Returns false if the ref type is a function type.
+    return AbstractType::Handle(type()).HasResolvedTypeClass();
+  }
   RawAbstractType* type() const { return raw_ptr()->type_; }
   void set_type(const AbstractType& value) const;
   virtual RawClass* type_class() const {
     return AbstractType::Handle(type()).type_class();
   }
   virtual RawTypeArguments* arguments() const {
     return AbstractType::Handle(type()).arguments();
   }
   virtual intptr_t token_pos() const {
     return AbstractType::Handle(type()).token_pos();
@@ skipping 48 matching lines @@
 // Upon finalization, the TypeParameter index is changed to reflect its position
 // as type argument (rather than type parameter) of the parameterized class.
 // If the type parameter is declared without an extends clause, its bound is set
 // to the ObjectType.
 class TypeParameter : public AbstractType {
  public:
   virtual bool IsFinalized() const {
     ASSERT(raw_ptr()->type_state_ != RawTypeParameter::kFinalizedInstantiated);
     return raw_ptr()->type_state_ == RawTypeParameter::kFinalizedUninstantiated;
   }
-  void set_is_finalized() const;
+  virtual void SetIsFinalized() const;
   virtual bool IsBeingFinalized() const { return false; }
   virtual bool IsMalformed() const { return false; }
   virtual bool IsMalbounded() const { return false; }
   virtual bool IsMalformedOrMalbounded() const { return false; }
   virtual bool IsResolved() const { return true; }
   virtual bool HasResolvedTypeClass() const { return false; }
   RawClass* parameterized_class() const {
     return raw_ptr()->parameterized_class_;
   }
   RawString* name() const { return raw_ptr()->name_; }
@@ skipping 2155 matching lines @@
   static const intptr_t kInitialIndexSize = 1 << (kInitialIndexBits + 1);
 
   // Allocate a map, but leave all fields set to null.
   // Used during deserialization (since map might contain itself as key/value).
   static RawLinkedHashMap* NewUninitialized(Heap::Space space = Heap::kNew);
 
   friend class Class;
 };
 
 
-class Closure : public AllStatic {
+class Closure : public Instance {
  public:
-  static RawFunction* function(const Instance& closure) {
-    return *FunctionAddr(closure);
+  RawFunction* function() const { return raw_ptr()->function_; }
+  void set_function(const Function& function) const {
+    // TODO(regis): Only used from deferred_objects.cc. Remove once fixed.
+    StorePointer(&raw_ptr()->function_, function.raw());
   }
-  static intptr_t function_offset() {
-    return static_cast<intptr_t>(kFunctionOffset * kWordSize);
+  static intptr_t function_offset() { return OFFSET_OF(RawClosure, function_); }
+
+  RawContext* context() const { return raw_ptr()->context_; }
+  void set_context(const Context& context) const {
+    // TODO(regis): Only used from deferred_objects.cc. Remove once fixed.
+    StorePointer(&raw_ptr()->context_, context.raw());
+  }
+  static intptr_t context_offset() { return OFFSET_OF(RawClosure, context_); }
+
+  static intptr_t type_arguments_offset() {
+    return OFFSET_OF(RawClosure, type_arguments_);
   }
 
-  static RawContext* context(const Instance& closure) {
-    return *ContextAddr(closure);
-  }
-  static intptr_t context_offset() {
-    return static_cast<intptr_t>(kContextOffset * kWordSize);
+  static intptr_t InstanceSize() {
+    return RoundedAllocationSize(sizeof(RawClosure));
   }
 
-  static RawTypeArguments* GetTypeArguments(const Instance& closure) {
-    return *TypeArgumentsAddr(closure);
-  }
-  static void SetTypeArguments(const Instance& closure,
-                               const TypeArguments& value) {
-    ASSERT(value.IsNull() || value.IsCanonical());
-    closure.StorePointer(TypeArgumentsAddr(closure), value.raw());
-  }
-  static intptr_t type_arguments_offset() {
-    return static_cast<intptr_t>(kTypeArgumentsOffset * kWordSize);
+  // Returns true if all elements are OK for canonicalization.
+  virtual bool CheckAndCanonicalizeFields(const char** error_str) const {
+    // None of the fields of a closure are instances.
+    return true;
   }
 
-  static const char* ToCString(const Instance& closure);
-
-  static intptr_t InstanceSize() {
-    intptr_t size = sizeof(RawInstance) + (kNumFields * kWordSize);
-    ASSERT(size == Object::RoundedAllocationSize(size));
-    return size;
-  }
-
-  static RawInstance* New(const Function& function,
-                          const Context& context,
-                          Heap::Space space = Heap::kNew);
+  static RawClosure* New(const Function& function,
+                         const Context& context,
+                         Heap::Space space = Heap::kNew);
 
  private:
-  static const int kTypeArgumentsOffset = 1;
-  static const int kFunctionOffset = 2;
-  static const int kContextOffset = 3;
-  static const int kNumFields = 3;
+  static RawClosure* New();
 
-  static RawTypeArguments** TypeArgumentsAddr(const Instance& obj) {
-    ASSERT(obj.IsClosure());
-    return reinterpret_cast<RawTypeArguments**>(
-        reinterpret_cast<intptr_t>(obj.raw_ptr()) + type_arguments_offset());
-  }
-  static RawFunction** FunctionAddr(const Instance& obj) {
-    ASSERT(obj.IsClosure());
-    return reinterpret_cast<RawFunction**>(
-        reinterpret_cast<intptr_t>(obj.raw_ptr()) + function_offset());
-  }
-  static RawContext** ContextAddr(const Instance& obj) {
-    ASSERT(obj.IsClosure());
-    return reinterpret_cast<RawContext**>(
-        reinterpret_cast<intptr_t>(obj.raw_ptr()) + context_offset());
-  }
-  static void set_function(const Instance& closure,
-                           const Function& value) {
-    closure.StorePointer(FunctionAddr(closure), value.raw());
-  }
-  static void set_context(const Instance& closure,
-                          const Context& value) {
-    closure.StorePointer(ContextAddr(closure), value.raw());
-  }
-  static intptr_t NextFieldOffset() {
-    // Indicates this class cannot be extended by dart code.
-    return -kWordSize;
-  }
-  static RawFunction* GetFunction(RawObject* obj) {
-    return *(reinterpret_cast<RawFunction**>(
-        reinterpret_cast<intptr_t>(obj->ptr()) + function_offset()));
-  }
-
+  FINAL_HEAP_OBJECT_IMPLEMENTATION(Closure, Instance);
   friend class Class;
-  friend class SnapshotWriter;
 };
 
 
 class Capability : public Instance {
  public:
   uint64_t Id() const { return raw_ptr()->id_; }
 
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawCapability));
   }
@@ skipping 483 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_