sdk/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"
#include "vm/dart.h"
#include "vm/globals.h"
#include "vm/handles.h"
#include "vm/heap.h"
#include "vm/isolate.h"
#include "vm/os.h"
#include "vm/raw_object.h"
#include "vm/scanner.h"

namespace dart {

// Forward declarations.
#define DEFINE_FORWARD_DECLARATION(clazz)                                      \
  class clazz;
CLASS_LIST(DEFINE_FORWARD_DECLARATION)
#undef DEFINE_FORWARD_DECLARATION
class Assembler;
class LocalScope;

#define OBJECT_IMPLEMENTATION(object, super)                                   \
 public:  /* NOLINT */                                                         \
  Raw##object* raw() const { return reinterpret_cast<Raw##object*>(raw_); }    \
  void operator=(Raw##object* value) {                                         \
    initializeHandle(this, value);                                             \
  }                                                                            \
  bool Is##object() const { return true; }                                     \
  void operator^=(RawObject* value) {                                          \
    initializeHandle(this, value);                                             \
    ASSERT(IsNull() || Is##object());                                          \
  }                                                                            \
  static object& Handle(Isolate* islt, Raw##object* raw_ptr) {                 \
    object* obj = reinterpret_cast<object*>(VMHandles::AllocateHandle(islt));  \
    initializeHandle(obj, raw_ptr);                                            \
    return *obj;                                                               \
  }                                                                            \
  static object& Handle() {                                                    \
    return Handle(Isolate::Current(), object::null());                         \
  }                                                                            \
  static object& Handle(Raw##object* raw_ptr) {                                \
    return Handle(Isolate::Current(), raw_ptr);                                \
  }                                                                            \
  static object& CheckedHandle(Isolate* islt, RawObject* raw_ptr) {            \
    object* obj = reinterpret_cast<object*>(VMHandles::AllocateHandle(islt));  \
    initializeHandle(obj, raw_ptr);                                            \
    if (!obj->Is##object()) {                                                  \
      FATAL("Handle check failed.");                                           \
    }                                                                          \
    return *obj;                                                               \
  }                                                                            \
  static object& CheckedHandle(RawObject* raw_ptr) {                           \
    return CheckedHandle(Isolate::Current(), raw_ptr);                         \
  }                                                                            \
  static object& ZoneHandle(Isolate* isolate, Raw##object* raw_ptr) {          \
    object* obj = reinterpret_cast<object*>(                                   \
        VMHandles::AllocateZoneHandle(isolate));                               \
    initializeHandle(obj, raw_ptr);                                            \
    return *obj;                                                               \
  }                                                                            \
  static object& ZoneHandle() {                                                \
    return ZoneHandle(Isolate::Current(), object::null());                     \
  }                                                                            \
  static object& ZoneHandle(Raw##object* raw_ptr) {                            \
    return ZoneHandle(Isolate::Current(), raw_ptr);                            \
  }                                                                            \
  static object& CheckedZoneHandle(Isolate* isolate, RawObject* raw_ptr) {     \
    object* obj = reinterpret_cast<object*>(                                   \
        VMHandles::AllocateZoneHandle(isolate));                               \
    initializeHandle(obj, raw_ptr);                                            \
    if (!obj->Is##object()) {                                                  \
      FATAL("Handle check failed.");                                           \
    }                                                                          \
    return *obj;                                                               \
  }                                                                            \
  static object& CheckedZoneHandle(RawObject* raw_ptr) {                       \
    return CheckedZoneHandle(Isolate::Current(), raw_ptr);                     \
  }                                                                            \
  static Raw##object* null() {                                                 \
    return reinterpret_cast<Raw##object*>(Object::null());                     \
  }                                                                            \
  virtual const char* ToCString() const;                                       \
  static const ObjectKind kInstanceKind = k##object;                           \
 protected:  /* NOLINT */                                                      \
  object() : super() {}                                                        \
 private:  /* NOLINT */                                                        \
  /* Initialize the handle based on the raw_ptr in the presence of null. */    \
  static void initializeHandle(object* obj, RawObject* raw_ptr) {              \
    if (raw_ptr != Object::null()) {                                           \
      obj->SetRaw(raw_ptr);                                                    \
    } else {                                                                   \
      obj->raw_ = Object::null();                                              \
      object fake_object;                                                      \
      obj->set_vtable(fake_object.vtable());                                   \
    }                                                                          \
  }                                                                            \
  /* Disallow allocation, copy constructors and override super assignment. */  \
  void* operator new(size_t size);                                             \
  object(const object& value);                                                 \
  void operator=(Raw##super* value);                                           \
  void operator=(const object& value);                                         \
  void operator=(const super& value);                                          \

#define SNAPSHOT_READER_SUPPORT(object)                                        \
  static Raw##object* ReadFrom(SnapshotReader* reader,                         \
                               intptr_t object_id,                             \
                               intptr_t tags,                                  \
                               Snapshot::Kind);                                \
  friend class SnapshotReader;                                                 \

#define HEAP_OBJECT_IMPLEMENTATION(object, super)                              \
  OBJECT_IMPLEMENTATION(object, super);                                        \
  Raw##object* raw_ptr() const {                                               \
    ASSERT(raw() != null());                                                   \
    return raw()->ptr();                                                       \
  }                                                                            \
  SNAPSHOT_READER_SUPPORT(object)                                              \

class Object {
 public:
  // Index for Singleton internal VM classes,
  // this index is used in snapshots to refer to these classes directly.
  enum {
    kNullObject = 0,
    kSentinelObject,
    kClassClass,
    kNullClass,
    kDynamicClass,
    kVoidClass,
    kUnresolvedClassClass,
    kTypeClass,
    kTypeParameterClass,
    kInstantiatedTypeClass,
    kAbstractTypeArgumentsClass,
    kTypeArgumentsClass,
    kInstantiatedTypeArgumentsClass,
    kFunctionClass,
    kFieldClass,
    kTokenStreamClass,
    kScriptClass,
    kLibraryClass,
    kLibraryPrefixClass,
    kCodeClass,
    kInstructionsClass,
    kPcDescriptorsClass,
    kLocalVarDescriptorsClass,
    kExceptionHandlersClass,
    kContextClass,
    kContextScopeClass,
    kApiErrorClass,
    kLanguageErrorClass,
    kUnhandledExceptionClass,
    kUnwindErrorClass,
    kMaxId,
    kInvalidIndex = -1,
  };

  virtual ~Object() { }

  RawObject* raw() const { return raw_; }
  void operator=(RawObject* value) { SetRaw(value); }

  void set_tags(intptr_t value) const {
    // TODO(asiva): Remove the capability of setting tags in general. The mask
    // here only allows for canonical and from_snapshot flags to be set.
    ASSERT(!IsNull());
    uword tags = raw()->ptr()->tags_ & ~0x0000000c;
    raw()->ptr()->tags_ = tags | (value & 0x0000000c);
  }
  void SetCreatedFromSnapshot() const {
    ASSERT(!IsNull());
    raw()->SetCreatedFromSnapshot();
  }
  bool IsCanonical() const {
    ASSERT(!IsNull());
    return raw()->IsCanonical();
  }
  void SetCanonical() const {
    ASSERT(!IsNull());
    raw()->SetCanonical();
  }

  inline RawClass* clazz() const;
  static intptr_t class_offset() { return OFFSET_OF(RawObject, class_); }
  static intptr_t tags_offset() { return OFFSET_OF(RawObject, tags_); }

  // Class testers.
#define DEFINE_CLASS_TESTER(clazz)                                             \
  virtual bool Is##clazz() const { return false; }
CLASS_LIST_NO_OBJECT(DEFINE_CLASS_TESTER);
#undef DEFINE_CLASS_TESTER

  bool IsNull() const { return raw_ == null_; }

  virtual const char* ToCString() const {
    if (IsNull()) {
      return "null";
    } else {
      return "Object";
    }
  }

  bool IsNew() const { return raw()->IsNewObject(); }
  bool IsOld() const { return raw()->IsOldObject(); }

  // Print the object on stdout for debugging.
  void Print() const;

  bool IsZoneHandle() const {
    return VMHandles::IsZoneHandle(reinterpret_cast<uword>(this));
  }

  static Object& Handle(Isolate* isolate, RawObject* raw_ptr) {
    Object* obj = reinterpret_cast<Object*>(VMHandles::AllocateHandle(isolate));
    obj->SetRaw(raw_ptr);
    return *obj;
  }

  static Object& Handle() {
    return Handle(Isolate::Current(), null_);
  }

  static Object& Handle(RawObject* raw_ptr) {
    return Handle(Isolate::Current(), raw_ptr);
  }

  static Object& ZoneHandle(Isolate* isolate, RawObject* raw_ptr) {
    Object* obj = reinterpret_cast<Object*>(
        VMHandles::AllocateZoneHandle(isolate));
    obj->SetRaw(raw_ptr);
    return *obj;
  }

  static Object& ZoneHandle() {
    return ZoneHandle(Isolate::Current(), null_);
  }

  static Object& ZoneHandle(RawObject* raw_ptr) {
    return ZoneHandle(Isolate::Current(), raw_ptr);
  }

  static RawObject* null() { return null_; }

  // The sentinel is a value that cannot be produced by Dart code.
  // It can be used to mark special values, for example to distinguish
  // "uninitialized" fields.
  static RawInstance* sentinel() { return sentinel_; }
  // Value marking that we are transitioning from sentinel, e.g., computing
  // a field value. Used to detect circular initialization.
  static RawInstance* transition_sentinel() { return transition_sentinel_; }

  static RawClass* class_class() { return class_class_; }
  static RawClass* null_class() { return null_class_; }
  static RawClass* dynamic_class() { return dynamic_class_; }
  static RawClass* void_class() { return void_class_; }
  static RawClass* unresolved_class_class() { return unresolved_class_class_; }
  static RawClass* type_class() {
      return type_class_;
  }
  static RawClass* type_parameter_class() { return type_parameter_class_; }
  static RawClass* instantiated_type_class() {
      return instantiated_type_class_;
  }
  static RawClass* abstract_type_arguments_class() {
    return abstract_type_arguments_class_;
  }
  static RawClass* type_arguments_class() { return type_arguments_class_; }
  static RawClass* instantiated_type_arguments_class() {
      return instantiated_type_arguments_class_;
  }
  static RawClass* function_class() { return function_class_; }
  static RawClass* field_class() { return field_class_; }
  static RawClass* token_stream_class() { return token_stream_class_; }
  static RawClass* script_class() { return script_class_; }
  static RawClass* library_class() { return library_class_; }
  static RawClass* library_prefix_class() { return library_prefix_class_; }
  static RawClass* code_class() { return code_class_; }
  static RawClass* instructions_class() { return instructions_class_; }
  static RawClass* pc_descriptors_class() { return pc_descriptors_class_; }
  static RawClass* var_descriptors_class() { return var_descriptors_class_; }
  static RawClass* exception_handlers_class() {
    return exception_handlers_class_;
  }
  static RawClass* context_class() { return context_class_; }
  static RawClass* context_scope_class() { return context_scope_class_; }
  static RawClass* api_error_class() { return api_error_class_; }
  static RawClass* language_error_class() { return language_error_class_; }
  static RawClass* unhandled_exception_class() {
    return unhandled_exception_class_;
  }
  static RawClass* unwind_error_class() { return unwind_error_class_; }

  static int GetSingletonClassIndex(const RawClass* raw_class);
  static RawClass* GetSingletonClass(int index);
  static const char* GetSingletonClassName(int index);

  static RawClass* CreateAndRegisterInterface(const char* cname,
                                              const Script& script,
                                              const Library& lib);
  static void RegisterClass(const Class& cls,
                            const char* cname,
                            const Script& script,
                            const Library& lib);

  static RawError* Init(Isolate* isolate);
  static void InitFromSnapshot(Isolate* isolate);
  static void InitOnce();

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawObject));
  }

  static const ObjectKind kInstanceKind = kObject;

  enum TypeTestKind {
    kIsSubtypeOf,
    kIsAssignableTo
  };

 protected:
  // Used for extracting the C++ vtable during bringup.
  Object() : raw_(null_) {}

  uword raw_value() const {
    return reinterpret_cast<uword>(raw());
  }

  inline void SetRaw(RawObject* value);

  cpp_vtable vtable() const { return bit_copy<cpp_vtable>(*this); }
  void set_vtable(cpp_vtable value) { *vtable_address() = value; }

  static RawObject* Allocate(const Class& cls,
                             intptr_t size,
                             Heap::Space space);

  static intptr_t RoundedAllocationSize(intptr_t size) {
    return Utils::RoundUp(size, kObjectAlignment);
  }

  template<typename type> void StorePointer(type* addr, type value) const {
    // TODO(iposva): Implement real store barrier here.
    *addr = value;
    // Filter stores based on source and target.
    if (value->IsNewObject() && raw()->IsOldObject()) {
      uword ptr = reinterpret_cast<uword>(addr);
      Isolate::Current()->store_buffer()->AddPointer(ptr);
    }
  }

  RawObject* raw_;  // The raw object reference.

 private:
  static void InitializeObject(uword address, intptr_t size);

  cpp_vtable* vtable_address() const {
    return reinterpret_cast<cpp_vtable*>(reinterpret_cast<word>(this));
  }

  static cpp_vtable handle_vtable_;

  // The static values below are singletons shared between the different
  // isolates. They are all allocated in the non-GC'd Dart::vm_isolate_.
  static RawObject* null_;
  static RawInstance* sentinel_;
  static RawInstance* transition_sentinel_;

  static RawClass* class_class_;  // Class of the Class vm object.
  static RawClass* null_class_;  // Class of the null object.
  static RawClass* dynamic_class_;  // Class of the 'Dynamic' type.
  static RawClass* void_class_;  // Class of the 'void' type.
  static RawClass* unresolved_class_class_;  // Class of UnresolvedClass.
  static RawClass* type_class_;  // Class of Type.
  static RawClass* type_parameter_class_;  // Class of TypeParameter vm object.
  static RawClass* instantiated_type_class_;  // Class of InstantiatedType.
  // Class of AbstractTypeArguments vm object.
  static RawClass* abstract_type_arguments_class_;
  // Class of the TypeArguments vm object.
  static RawClass* type_arguments_class_;
  static RawClass* instantiated_type_arguments_class_;  // Class of Inst..ments.
  static RawClass* function_class_;  // Class of the Function vm object.
  static RawClass* field_class_;  // Class of the Field vm object.
  static RawClass* token_stream_class_;  // Class of the TokenStream vm object.
  static RawClass* script_class_;  // Class of the Script vm object.
  static RawClass* library_class_;  // Class of the Library vm object.
  static RawClass* library_prefix_class_;  // Class of Library prefix vm object.
  static RawClass* code_class_;  // Class of the Code vm object.
  static RawClass* instructions_class_;  // Class of the Instructions vm object.
  static RawClass* pc_descriptors_class_;  // Class of PcDescriptors vm object.
  static RawClass* var_descriptors_class_;  // Class of LocalVarDescriptors.
  static RawClass* exception_handlers_class_;  // Class of ExceptionHandlers.
  static RawClass* context_class_;  // Class of the Context vm object.
  static RawClass* context_scope_class_;  // Class of ContextScope vm object.
  static RawClass* api_error_class_;  // Class of ApiError.
  static RawClass* language_error_class_;  // Class of LanguageError.
  static RawClass* unhandled_exception_class_;  // Class of UnhandledException.
  static RawClass* unwind_error_class_;  // Class of UnwindError.

  friend void RawObject::Validate() const;
  friend class SnapshotReader;

  // Disallow allocation.
  void* operator new(size_t size);
  // Disallow copy constructor.
  DISALLOW_COPY_AND_ASSIGN(Object);
};


class Class : public Object {
 public:
  intptr_t instance_size() const {
    ASSERT(is_finalized() || is_prefinalized());
    return raw_ptr()->instance_size_;
  }
  void set_instance_size(intptr_t value) const {
    ASSERT(Utils::IsAligned(value, kObjectAlignment));
    raw_ptr()->instance_size_ = value;
  }
  static intptr_t instance_size_offset() {
    return OFFSET_OF(RawClass, instance_size_);
  }

  intptr_t next_field_offset() const {
    return raw_ptr()->next_field_offset_;
  }
  void set_next_field_offset(intptr_t value) const {
    ASSERT((Utils::IsAligned(value, kObjectAlignment) &&
            (value == raw_ptr()->instance_size_)) ||
           (!Utils::IsAligned(value, kObjectAlignment) &&
            (value + kWordSize == raw_ptr()->instance_size_)));
    raw_ptr()->next_field_offset_ = value;
  }

  cpp_vtable handle_vtable() const { return raw_ptr()->handle_vtable_; }
  void set_handle_vtable(cpp_vtable value) const {
    raw_ptr()->handle_vtable_ = value;
  }

  ObjectKind instance_kind() const { return raw_ptr()->instance_kind_; }
  void set_instance_kind(ObjectKind value) {
    raw_ptr()->instance_kind_ = value;
  }

  RawString* Name() const;

  RawScript* script() const { return raw_ptr()->script_; }

  intptr_t token_index() const { return raw_ptr()->token_index_; }

  // 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.
  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
  // '<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.
  RawType* SignatureType() const;

  RawLibrary* library() const { return raw_ptr()->library_; }
  void set_library(const Library& value) const;

  // The type parameters are specified as an array of TypeParameter.
  RawTypeArguments* type_parameters() const {
      return raw_ptr()->type_parameters_;
  }
  void set_type_parameters(const TypeArguments& value) const;
  intptr_t NumTypeParameters() const;

  // Type parameter bounds (implicitly Dynamic if not explicitly specified) as
  // an array of AbstractType.
  RawTypeArguments* type_parameter_bounds() const {
    return raw_ptr()->type_parameter_bounds_;
  }
  void set_type_parameter_bounds(const TypeArguments& value) const;

  // Return a TypeParameter if the type_name is a type parameter of this class.
  // Return null otherwise.
  RawTypeParameter* LookupTypeParameter(const String& type_name,
                                        intptr_t token_index) const;

  // The type argument vector is flattened and includes the type arguments of
  // the super class.
  bool HasTypeArguments() const;
  intptr_t NumTypeArguments() const;

  // If this class is parameterized, each instance has a type_arguments field.
  static const intptr_t kNoTypeArguments = -1;
  intptr_t type_arguments_instance_field_offset() const {
    ASSERT(is_finalized() || is_prefinalized());
    return raw_ptr()->type_arguments_instance_field_offset_;
  }
  void set_type_arguments_instance_field_offset(intptr_t value) const {
    raw_ptr()->type_arguments_instance_field_offset_ = value;
  }

  // The super type of this class, Object type if not explicitly specified.
  RawType* super_type() const { return raw_ptr()->super_type_; }
  void set_super_type(const Type& value) const;

  // Asserts that the class of the super type has been resolved.
  RawClass* SuperClass() const;

  // Return true if this interface has a factory class.
  bool HasFactoryClass() const;

  // Return true if the factory class of this interface is resolved.
  bool HasResolvedFactoryClass() const;

  // Return the resolved factory class of this interface.
  RawClass* FactoryClass() const;

  // Return the unresolved factory class of this interface.
  RawUnresolvedClass* UnresolvedFactoryClass() const;

  // Set the resolved or unresolved factory class of this interface.
  void set_factory_class(const Object& value) const;

  // Interfaces is an array of Types.
  RawArray* interfaces() const { return raw_ptr()->interfaces_; }
  void set_interfaces(const Array& value) const;

  RawArray* functions_cache() const { return raw_ptr()->functions_cache_; }
  void set_functions_cache(const Array& value) const;

  static intptr_t functions_cache_offset() {
    return OFFSET_OF(RawClass, functions_cache_);
  }

  // Check if this class represents the class of null.
  bool IsNullClass() const { return raw() == Object::null_class(); }

  // Check if this class represents the 'Dynamic' class.
  bool IsDynamicClass() const { return raw() == Object::dynamic_class(); }

  // Check if this class represents the 'void' class.
  bool IsVoidClass() const { return raw() == Object::void_class(); }

  // Check if this class represents the 'Object' class.
  bool IsObjectClass() const;

  // Check if this class represents a signature class.
  bool IsSignatureClass() const {
    return signature_function() != Object::null();
  }

  // Check if this class represents a canonical signature class, i.e. not an
  // alias as defined in a typedef.
  bool IsCanonicalSignatureClass() const;

  // Check the "more specific than" relationship.
  bool IsMoreSpecificThan(
      const AbstractTypeArguments& type_arguments,
      const Class& other,
      const AbstractTypeArguments& other_type_arguments) const;

  // Check the subtype relationship.
  bool IsSubtypeOf(const AbstractTypeArguments& type_arguments,
                   const Class& other,
                   const AbstractTypeArguments& other_type_arguments) const {
    return TestType(kIsSubtypeOf,
                    type_arguments,
                    other,
                    other_type_arguments);
  }

  // Check the assignability relationship.
  bool IsAssignableTo(const AbstractTypeArguments& type_arguments,
                      const Class& dst,
                      const AbstractTypeArguments& dst_type_arguments) const {
    return TestType(kIsAssignableTo,
                    type_arguments,
                    dst,
                    dst_type_arguments);
  }

  // Check if this is the top level class.
  bool IsTopLevel() const;

  RawArray* fields() const { return raw_ptr()->fields_; }
  void SetFields(const Array& value) const;

  RawArray* functions() const { return raw_ptr()->functions_; }
  void SetFunctions(const Array& value) const;

  RawFunction* LookupDynamicFunction(const String& name) const;
  RawFunction* LookupStaticFunction(const String& name) const;
  RawFunction* LookupConstructor(const String& name) const;
  RawFunction* LookupFactory(const String& name) const;
  RawFunction* LookupFunction(const String& name) const;
  RawFunction* LookupGetterFunction(const String& name) const;
  RawFunction* LookupSetterFunction(const String& name) const;
  RawFunction* LookupFunctionAtToken(intptr_t token_index) 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;

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawClass));
  }

  bool is_interface() const {
    return raw_ptr()->is_interface_;
  }
  void set_is_interface() const;

  bool is_finalized() const {
    return raw_ptr()->class_state_ == RawClass::kFinalized;
  }
  void set_is_finalized() const;

  bool is_prefinalized() const {
    return raw_ptr()->class_state_ == RawClass::kPreFinalized;
  }

  bool is_const() const {
    return raw_ptr()->is_const_;
  }
  void set_is_const() const;

  int num_native_fields() const {
    return raw_ptr()->num_native_fields_;
  }
  void set_num_native_fields(int value) const {
    raw_ptr()->num_native_fields_ = value;
  }
  static intptr_t num_native_fields_offset() {
    return OFFSET_OF(RawClass, num_native_fields_);
  }

  RawCode* allocation_stub() const {
    return raw_ptr()->allocation_stub_;
  }
  void set_allocation_stub(const Code& value) const;

  RawArray* constants() const;

  void Finalize() const;

  // Allocate a class used for VM internal objects.
  template <class FakeObject> static RawClass* New();

  // Allocate an instance class which has a VM implementation.
  template <class FakeInstance> static RawClass* New(const String& name,
                                                     const Script& script,
                                                     intptr_t token_index);

  // Allocate instance classes and interfaces.
  static RawClass* New(const String& name,
                       const Script& script,
                       intptr_t token_index);
  static RawClass* NewInterface(const String& name,
                                const Script& script,
                                intptr_t token_index);
  static RawClass* NewNativeWrapper(Library* library,
                                    const String& name,
                                    int num_fields);

  // 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.
  static RawClass* NewSignatureClass(const String& name,
                                     const Function& signature_function,
                                     const Script& script);

  // Return a class object corresponding to the specified kind. If
  // a canonicalized version of it exists then that object is returned
  // otherwise a new object is allocated and returned.
  static RawClass* GetClass(ObjectKind kind);

 private:
  void set_name(const String& value) const;
  void set_script(const Script& value) const;
  void set_token_index(intptr_t value) const;
  void set_signature_function(const Function& value) const;
  void set_signature_type(const AbstractType& value) const;
  void set_class_state(int8_t state) const;

  void set_constants(const Array& value) const;

  void set_canonical_types(const Array& value) const;
  RawArray* canonical_types() const;

  void CalculateFieldOffsets() const;

  // Check the subtype or assignability relationship.
  bool TestType(TypeTestKind test,
                const AbstractTypeArguments& type_arguments,
                const Class& other,
                const AbstractTypeArguments& other_type_arguments) const;

  // Assigns empty array to all raw class array fields.
  void InitEmptyFields();

  RawFunction* LookupAccessorFunction(const char* prefix,
                                      intptr_t prefix_length,
                                      const String& name) const;

  HEAP_OBJECT_IMPLEMENTATION(Class, Object);
  friend class Object;
  friend class Instance;
  friend class Type;
};


// 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 {
    return raw_ptr()->library_prefix_;
  }
  RawString* ident() const { return raw_ptr()->ident_; }
  intptr_t token_index() const { return raw_ptr()->token_index_; }

  RawClass* factory_signature_class() const {
    return raw_ptr()->factory_signature_class_;
  }
  void set_factory_signature_class(const Class& value) const;

  RawString* Name() const;

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawUnresolvedClass));
  }
  static RawUnresolvedClass* New(const LibraryPrefix& library_prefix,
                                 const String& ident,
                                 intptr_t token_index);

 private:
  void set_library_prefix(const LibraryPrefix& library_prefix) const;
  void set_ident(const String& ident) const;
  void set_token_index(intptr_t token_index) const;

  static RawUnresolvedClass* New();

  HEAP_OBJECT_IMPLEMENTATION(UnresolvedClass, Object);
  friend class Class;
};


// AbstractType is an abstract superclass.
// Subclasses of AbstractType are Type, TypeParameter, and
// InstantiatedType.
//
// Caution: 'RawAbstractType*' denotes a 'raw' pointer to a VM object of class
// AbstractType, as opposed to 'AbstractType' denoting a 'handle' to the same
// object. 'RawAbstractType' does not relate to a 'raw type', as opposed to a
// 'cooked type' or 'rare type'.
class AbstractType : public Object {
 public:
  virtual bool IsFinalized() const;
  virtual bool IsBeingFinalized() const;
  virtual bool IsResolved() const;
  virtual bool HasResolvedTypeClass() const;
  virtual RawClass* type_class() const;
  virtual RawUnresolvedClass* unresolved_class() const;
  virtual RawAbstractTypeArguments* arguments() const;
  virtual intptr_t token_index() const;
  virtual bool IsInstantiated() const;
  virtual bool Equals(const AbstractType& other) const;

  // Instantiate this type using the given type argument vector.
  // Return a new type, or return 'this' if it is already instantiated.
  virtual RawAbstractType* InstantiateFrom(
      const AbstractTypeArguments& instantiator_type_arguments) const;

  // Return the canonical version of this type.
  virtual RawAbstractType* Canonicalize() const;

  // The name of this type, including the names of its type arguments, if any.
  virtual RawString* Name() const;

  // The index of this type parameter. Fail if not a type parameter.
  virtual intptr_t Index() const;

  // The name of this type's class, i.e. without the type argument names of this
  // type.
  RawString* ClassName() const;

  // Check if this type represents the 'Dynamic' type.
  bool IsDynamicType() const {
    return HasResolvedTypeClass() && (type_class() == Object::dynamic_class());
  }

  // Check if this type represents the 'void' type.
  bool IsVoidType() const {
    return HasResolvedTypeClass() && (type_class() == Object::void_class());
  }

  bool IsObjectType() const {
    return HasResolvedTypeClass() &&
        Class::Handle(type_class()).IsObjectClass();
  }

  // Check if this type represents the 'bool' interface.
  bool IsBoolInterface() const;

  // Check if this type represents the 'int' interface.
  bool IsIntInterface() const;

  // Check if this type represents the 'double' interface.
  bool IsDoubleInterface() const;

  // Check if this type represents the 'num' interface.
  bool IsNumberInterface() const;

  // Check if this type represents the 'String' interface.
  bool IsStringInterface() const;

  // Check if this type represents the 'Function' interface.
  bool IsFunctionInterface() const;

  // Check if this type represents the 'List' interface.
  bool IsListInterface() const;

  // Check if this type is an interface type.
  bool IsInterfaceType() const {
    if (!HasResolvedTypeClass()) {
      return false;
    }
    const Class& cls = Class::Handle(type_class());
    return !cls.IsNull() && cls.is_interface();
  }

  // Check the "more specific than" relationship.
  bool IsMoreSpecificThan(const AbstractType& other) const;

  // Check the subtype relationship.
  bool IsSubtypeOf(const AbstractType& other) const {
    return Test(kIsSubtypeOf, other);
  }

  // Check the assignability relationship.
  bool IsAssignableTo(const AbstractType& dst) const {
    return Test(kIsAssignableTo, dst);
  }

  static RawAbstractType* NewTypeParameter(intptr_t index,
                                           const String& name,
                                           intptr_t token_index);

  static RawAbstractType* NewInstantiatedType(
      const AbstractType& uninstantiated_type,
      const AbstractTypeArguments& instantiator_type_arguments);

 protected:
  // Check the subtype or assignability relationship.
  bool Test(TypeTestKind test, const AbstractType& other) const;

  HEAP_OBJECT_IMPLEMENTATION(AbstractType, Object);
  friend class Class;
};


// A Type consists of a class, possibly parameterized with type
// arguments. Example: C<T1, T2>.
// An unresolved class is a String specifying the class name.
class Type : public AbstractType {
 public:
  virtual bool IsFinalized() const {
    return raw_ptr()->type_state_ == RawType::kFinalized;
  }
  void set_is_finalized() const;
  virtual bool IsBeingFinalized() const {
    return raw_ptr()->type_state_ == RawType::kBeingFinalized;
  }
  void set_is_being_finalized() const;
  virtual bool IsResolved() const;  // Class and all arguments classes resolved.
  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 RawAbstractTypeArguments* arguments() const;
  void set_arguments(const AbstractTypeArguments& value) const;
  virtual intptr_t token_index() const { return raw_ptr()->token_index_; }
  virtual bool IsInstantiated() const;
  virtual bool Equals(const AbstractType& other) const;
  virtual RawAbstractType* InstantiateFrom(
      const AbstractTypeArguments& instantiator_type_arguments) const;
  virtual RawAbstractType* Canonicalize() const;

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawType));
  }

  // The type of the literal 'null'.
  static RawType* NullType();

  // The 'Dynamic' type.
  static RawType* DynamicType();

  // The 'void' type.
  static RawType* VoidType();

  // The 'Object' type.
  static RawType* ObjectType();

  // The 'bool' interface type.
  static RawType* BoolInterface();

  // The 'int' interface type.
  static RawType* IntInterface();

  // The 'double' interface type.
  static RawType* DoubleInterface();

  // The 'num' interface type.
  static RawType* NumberInterface();

  // The 'String' interface type.
  static RawType* StringInterface();

  // The 'Function' interface type.
  static RawType* FunctionInterface();

  // The 'List' interface type.
  static RawType* ListInterface();

  // The finalized type of the given non-parameterized class.
  static RawType* NewNonParameterizedType(const Class& type_class);

  static RawType* New(const Object& clazz,
                      const AbstractTypeArguments& arguments,
                      intptr_t token_index);

 private:
  void set_token_index(intptr_t token_index) const;
  void set_type_state(int8_t state) const;

  static RawType* New();

  HEAP_OBJECT_IMPLEMENTATION(Type, AbstractType);
  friend class Class;
};


// A TypeParameter, in the context of a parameterized class, references a type
// parameter of a class by its index (and by its name for debugging purposes).
// For example, the type parameter 'V' is specified as index 1 in the context of
// the class HashMap<K, V>. At compile time, the TypeParameter is not
// instantiated yet, i.e. it is only a place holder.
// Upon finalization, the TypeParameter index is changed to reflect its position
// as type argument (rather than type parameter) of the enclosing class.
class TypeParameter : public AbstractType {
 public:
  virtual bool IsFinalized() const {
    return raw_ptr()->type_state_ == RawTypeParameter::kFinalized;
  }
  void set_is_finalized() const;
  virtual bool IsBeingFinalized() const { return false; }
  virtual bool IsResolved() const { return true; }
  virtual bool HasResolvedTypeClass() const { return false; }
  virtual RawString* Name() const { return raw_ptr()->name_; }
  virtual intptr_t Index() const { return raw_ptr()->index_; }
  void set_index(intptr_t value) const;
  virtual intptr_t token_index() const { return raw_ptr()->token_index_; }
  virtual bool IsInstantiated() const { return false; }
  virtual bool Equals(const AbstractType& other) const;
  virtual RawAbstractType* InstantiateFrom(
      const AbstractTypeArguments& instantiator_type_arguments) const;
  virtual RawAbstractType* Canonicalize() const { return raw(); }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawTypeParameter));
  }

  static RawTypeParameter* New(intptr_t index,
                               const String& name,
                               intptr_t token_index);

 private:
  void set_name(const String& value) const;
  void set_token_index(intptr_t token_index) const;
  void set_type_state(int8_t state) const;
  static RawTypeParameter* New();

  HEAP_OBJECT_IMPLEMENTATION(TypeParameter, AbstractType);
  friend class Class;
};


// An instance of InstantiatedType is never encountered at compile time, but
// only at run time, when type parameters can be matched to actual types.
// An instance of InstantiatedType consists of an uninstantiated AbstractType
// object and of a AbstractTypeArguments object. The type is uninstantiated,
// because it refers to at least one TypeParameter object, i.e. to a type that
// is not known at compile time.
// The type argument vector is the instantiator, because each type parameter
// with index i in the uninstantiated type can be substituted (or
// "instantiated") with the type at index i in the type argument vector.
class InstantiatedType : public AbstractType {
 public:
  virtual bool IsFinalized() const { return true; }
  virtual bool IsBeingFinalized() const { return false; }
  virtual bool IsResolved() const { return true; }
  virtual bool HasResolvedTypeClass() const { return true; }
  virtual RawClass* type_class() const;
  virtual RawAbstractTypeArguments* arguments() const;
  virtual intptr_t token_index() const;
  virtual bool IsInstantiated() const { return true; }

  RawAbstractType* uninstantiated_type() const {
    return raw_ptr()->uninstantiated_type_;
  }
  RawAbstractTypeArguments* instantiator_type_arguments() const {
    return raw_ptr()->instantiator_type_arguments_;
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawInstantiatedType));
  }

  static RawInstantiatedType* New(
      const AbstractType& uninstantiated_type,
      const AbstractTypeArguments& instantiator_type_arguments);

 private:
  void set_uninstantiated_type(const AbstractType& value) const;
  void set_instantiator_type_arguments(
      const AbstractTypeArguments& value) const;
  static RawInstantiatedType* New();

  HEAP_OBJECT_IMPLEMENTATION(InstantiatedType, AbstractType);
  friend class Class;
};


// AbstractTypeArguments is an abstract superclass.
// Subclasses of AbstractTypeArguments are TypeArguments and InstantiatedTypes.
class AbstractTypeArguments : public Object {
 public:
  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.
  virtual RawAbstractTypeArguments* InstantiateFrom(
      const AbstractTypeArguments& instantiator_type_arguments) const;

  // Do not canonicalize InstantiatedTypeArguments or NULL objects
  virtual RawAbstractTypeArguments* Canonicalize() const { return this->raw(); }

  // Check if this type argument vector consists solely of DynamicType,
  // considering only a prefix of length 'len'.
  bool IsDynamicTypes(intptr_t len) const;

  // Check the "more specific than" relationship, considering only a prefix of
  // length 'len'.
  bool IsMoreSpecificThan(
      const AbstractTypeArguments& other, intptr_t len) const;

  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;

 protected:
  HEAP_OBJECT_IMPLEMENTATION(AbstractTypeArguments, Object);
  friend class Class;
};


// A TypeArguments is an array of AbstractType.
class TypeArguments : public AbstractTypeArguments {
 public:
  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;
  // Canonicalize only if instantiated, otherwise returns 'this'.
  virtual RawAbstractTypeArguments* Canonicalize() const;

  virtual RawAbstractTypeArguments* InstantiateFrom(
      const AbstractTypeArguments& instantiator_type_arguments) const;

  static intptr_t length_offset() {
    return OFFSET_OF(RawTypeArguments, length_);
  }

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawTypeArguments) == OFFSET_OF(RawTypeArguments, types_));
    return 0;
  }

  static intptr_t InstanceSize(intptr_t len) {
    // Ensure that the types_ is not adding to the object length.
    ASSERT(sizeof(RawTypeArguments) == (sizeof(RawObject) + (1 * kWordSize)));
    return RoundedAllocationSize(sizeof(RawTypeArguments) + (len * kWordSize));
  }

  static RawTypeArguments* New(intptr_t len);

 private:
  // Make sure that the array size cannot wrap around.
  static const intptr_t kMaxTypes = 512 * 1024 * 1024;
  RawAbstractType** TypeAddr(intptr_t index) const;
  void SetLength(intptr_t value);

  HEAP_OBJECT_IMPLEMENTATION(TypeArguments, AbstractTypeArguments);
  friend class Class;
};


// An instance of InstantiatedTypeArguments is never encountered at compile
// time, but only at run time, when type parameters can be matched to actual
// types.
// An instance of InstantiatedTypeArguments consists of a pair of
// AbstractTypeArguments objects. The first type argument vector is
// uninstantiated, because it contains type expressions referring to at least
// one TypeParameter object, i.e. to a type that is not known at compile time.
// The second type argument vector is the instantiator, because each type
// parameter with index i in the first vector can be substituted (or
// "instantiated") with the type at index i in the second type argument vector.
class InstantiatedTypeArguments : public AbstractTypeArguments {
 public:
  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 { return true; }
  virtual bool IsInstantiated() const { return true; }
  virtual bool IsUninstantiatedIdentity() const  { return false; }

  RawAbstractTypeArguments* uninstantiated_type_arguments() const {
    return raw_ptr()->uninstantiated_type_arguments_;
  }
  static intptr_t uninstantiated_type_arguments_offset() {
    return OFFSET_OF(RawInstantiatedTypeArguments,
                     uninstantiated_type_arguments_);
  }

  RawAbstractTypeArguments* instantiator_type_arguments() const {
    return raw_ptr()->instantiator_type_arguments_;
  }
  static intptr_t instantiator_type_arguments_offset() {
    return OFFSET_OF(RawInstantiatedTypeArguments,
                     instantiator_type_arguments_);
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawInstantiatedTypeArguments));
  }

  static RawInstantiatedTypeArguments* New(
      const AbstractTypeArguments& uninstantiated_type_arguments,
      const AbstractTypeArguments& instantiator_type_arguments);

 private:
  void set_uninstantiated_type_arguments(
      const AbstractTypeArguments& value) const;
  void set_instantiator_type_arguments(
      const AbstractTypeArguments& value) const;
  static RawInstantiatedTypeArguments* New();

  HEAP_OBJECT_IMPLEMENTATION(InstantiatedTypeArguments, AbstractTypeArguments);
  friend class Class;
};


class Function : public Object {
 public:
  RawString* name() const { return raw_ptr()->name_; }

  // Build a string of the form '<T, R>(T, [b: B, c: C]) => R' representing the
  // signature of the given function.
  RawString* Signature() const {
    return BuildSignature(false, 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
  // '<T, R>(T, [b: B, c: C]) => R') are instantiated using the given
  // instantiator type argument vector (e.g. '<A, D>').
  RawString* InstantiatedSignatureFrom(
      const AbstractTypeArguments& instantiator) const {
    return BuildSignature(true, instantiator);
  }

  // Returns true if the signature of this function is instantiated, i.e. if it
  // does not involve generic parameter types or generic result type.
  bool HasInstantiatedSignature() const;

  RawClass* owner() const { return raw_ptr()->owner_; }
  void set_owner(const Class& value) const;

  RawAbstractType* result_type() const { return raw_ptr()->result_type_; }
  void set_result_type(const AbstractType& value) const;

  RawAbstractType* ParameterTypeAt(intptr_t index) const;
  void SetParameterTypeAt(intptr_t index, const AbstractType& value) const;
  void set_parameter_types(const Array& value) const;

  // Parameter names are valid for all valid parameter indices, and are not
  // limited to named optional parameters.
  RawString* ParameterNameAt(intptr_t index) const;
  void SetParameterNameAt(intptr_t index, const String& value) const;
  void set_parameter_names(const Array& value) const;

  RawCode* code() const { return raw_ptr()->code_; }
  // Sets function's code and code's function.
  void SetCode(const Code& value) const;
  RawCode* unoptimized_code() const { return raw_ptr()->unoptimized_code_; }
  void set_unoptimized_code(const Code& value) const;
  static intptr_t code_offset() { return OFFSET_OF(RawFunction, code_); }
  inline bool HasCode() const;

  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_; }

  // 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;

  RawCode* closure_allocation_stub() const {
    return raw_ptr()->closure_allocation_stub_;
  }
  void set_closure_allocation_stub(const Code& value) const;

  // Return the closure function implicitly created for this function.
  // If none exists yet, create one and remember it.
  RawFunction* ImplicitClosureFunction() const;

  RawFunction::Kind kind() const { return raw_ptr()->kind_; }

  bool is_static() const { return raw_ptr()->is_static_; }
  bool is_const() const { return raw_ptr()->is_const_; }
  bool IsConstructor() const {
    return (kind() == RawFunction::kConstructor) && !is_static();
  }
  bool IsFactory() const {
    return (kind() == RawFunction::kConstructor) && is_static();
  }
  bool IsAbstract() const {
    return kind() == RawFunction::kAbstract;
  }
  bool IsDynamicFunction() const {
    if (is_static()) {
      return false;
    }
    switch (kind()) {
      case RawFunction::kFunction:
      case RawFunction::kGetterFunction:
      case RawFunction::kSetterFunction:
      case RawFunction::kImplicitGetter:
      case RawFunction::kImplicitSetter:
        return true;
      case RawFunction::kConstructor:
      case RawFunction::kConstImplicitGetter:
      case RawFunction::kAbstract:
        return false;
      default:
        UNREACHABLE();
        return false;
    }
  }
  bool IsStaticFunction() const {
    if (!is_static()) {
      return false;
    }
    switch (kind()) {
      case RawFunction::kFunction:
      case RawFunction::kGetterFunction:
      case RawFunction::kSetterFunction:
      case RawFunction::kImplicitGetter:
      case RawFunction::kImplicitSetter:
      case RawFunction::kConstImplicitGetter:
        return true;
      case RawFunction::kConstructor:
        return false;
      default:
        UNREACHABLE();
        return false;
    }
  }
  bool IsInFactoryScope() const;

  intptr_t token_index() const { return raw_ptr()->token_index_; }

  intptr_t end_token_index() const { return raw_ptr()->end_token_index_; }
  void set_end_token_index(intptr_t value) const {
    raw_ptr()->end_token_index_ = value;
  }

  static intptr_t num_fixed_parameters_offset() {
    return OFFSET_OF(RawFunction, num_fixed_parameters_);
  }
  intptr_t num_fixed_parameters() const {
    return raw_ptr()->num_fixed_parameters_;
  }
  void set_num_fixed_parameters(intptr_t value) const;

  static intptr_t num_optional_parameters_offset() {
    return OFFSET_OF(RawFunction, num_optional_parameters_);
  }
  intptr_t num_optional_parameters() const {
    return raw_ptr()->num_optional_parameters_;
  }
  void set_num_optional_parameters(intptr_t value) const;

  static intptr_t invocation_counter_offset() {
    return OFFSET_OF(RawFunction, invocation_counter_);
  }
  intptr_t invocation_counter() const {
    return raw_ptr()->invocation_counter_;
  }
  void set_invocation_counter(intptr_t value) const {
    raw_ptr()->invocation_counter_ = value;
  }

  intptr_t deoptimization_counter() const {
    return raw_ptr()->deoptimization_counter_;
  }
  void set_deoptimization_counter(intptr_t value) const {
    raw_ptr()->deoptimization_counter_ = value;
  }

  bool is_optimizable() const {
    return raw_ptr()->is_optimizable_;
  }
  void set_is_optimizable(bool value) const;

  intptr_t NumberOfParameters() const;

  bool AreValidArgumentCounts(int num_arguments, int num_named_arguments) const;
  bool AreValidArguments(int num_arguments, const Array& argument_names) const;

  // Fully qualified name uniquely identifying the function under gdb and during
  // ast printing. The special ':' character, if present, is replaced by '_'.
  const char* ToFullyQualifiedCString() const;

  // Returns true if this function has parameters that are compatible with the
  // parameters of the other function in order for this function to override the
  // other function. Parameter types are ignored.
  bool HasCompatibleParametersWith(const Function& other) const;

  // Returns true if the type of this function is a subtype of the type of
  // the other function.
  bool IsSubtypeOf(const AbstractTypeArguments& type_arguments,
                   const Function& other,
                   const AbstractTypeArguments& other_type_arguments) const {
    return TestType(kIsSubtypeOf,
                    type_arguments,
                    other,
                    other_type_arguments);
  }

  // Returns true if the type of this function can be assigned to the type of
  // the destination function.
  bool IsAssignableTo(const AbstractTypeArguments& type_arguments,
                      const Function& dst,
                      const AbstractTypeArguments& dst_type_arguments) const {
    return TestType(kIsAssignableTo,
                    type_arguments,
                    dst,
                    dst_type_arguments);
  }

  // Returns true if this function represents a (possibly implicit) closure
  // function.
  bool IsClosureFunction() const {
    return kind() == RawFunction::kClosureFunction;
  }

  // Returns true if this function represents an implicit closure function.
  bool IsImplicitClosureFunction() const;

  // Returns true if this function represents a non implicit closure function.
  bool IsNonImplicitClosureFunction() const {
    return IsClosureFunction() && !IsImplicitClosureFunction();
  }

  // Returns true if this function represents an implicit static closure
  // function.
  bool IsImplicitStaticClosureFunction() const {
    return is_static() && IsImplicitClosureFunction();
  }

  // Returns true if this function represents an implicit instance closure
  // function.
  bool IsImplicitInstanceClosureFunction() const {
    return !is_static() && IsImplicitClosureFunction();
  }

  // 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 intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawFunction));
  }

  static RawFunction* New(const String& name,
                          RawFunction::Kind kind,
                          bool is_static,
                          bool is_const,
                          intptr_t token_index);

  // 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.
  static RawFunction* NewClosureFunction(const String& name,
                                         const Function& parent,
                                         intptr_t token_index);

  static const int kCtorPhaseInit = 1 << 0;
  static const int kCtorPhaseBody = 1 << 1;
  static const int kCtorPhaseAll = (kCtorPhaseInit | kCtorPhaseBody);

 private:
  void set_name(const String& value) const;
  void set_kind(RawFunction::Kind value) const;
  void set_is_static(bool is_static) const;
  void set_is_const(bool is_const) const;
  void set_parent_function(const Function& value) const;
  void set_token_index(intptr_t value) const;
  void set_implicit_closure_function(const Function& value) const;
  static RawFunction* New();

  RawString* BuildSignature(bool instantiate,
                            const AbstractTypeArguments& instantiator) const;

  // Checks the subtype or assignability relationship between the type of this
  // function and the type of the other function.
  bool TestType(TypeTestKind test,
                const AbstractTypeArguments& type_arguments,
                const Function& other,
                const AbstractTypeArguments& other_type_arguments) const;

  // Checks the type of the formal parameter at the given position for
  // assignability relationship between the type of this function and the type
  // of the other function.
  bool TestParameterType(
      intptr_t parameter_position,
      const AbstractTypeArguments& type_arguments,
      const Function& other,
      const AbstractTypeArguments& other_type_arguments) const;

  HEAP_OBJECT_IMPLEMENTATION(Function, Object);
  friend class Class;
};


class Field : public Object {
 public:
  RawString* name() const { return raw_ptr()->name_; }
  bool is_static() const { return raw_ptr()->is_static_; }
  bool is_final() const { return raw_ptr()->is_final_; }

  inline intptr_t Offset() const;
  inline void SetOffset(intptr_t value) const;

  RawInstance* value() const;
  void set_value(const Instance& value) const;

  RawClass* owner() const { return raw_ptr()->owner_; }
  void set_owner(const Class& value) const {
    StorePointer(&raw_ptr()->owner_, value.raw());
  }

  RawAbstractType* type() const  { return raw_ptr()->type_; }
  void set_type(const AbstractType& value) const;

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawField));
  }

  static RawField* New(const String& name,
                       bool is_static,
                       bool is_final,
                       intptr_t token_index);

  static intptr_t value_offset() { return OFFSET_OF(RawField, value_); }

  intptr_t token_index() const { return raw_ptr()->token_index_; }

  bool has_initializer() const { return raw_ptr()->has_initializer_; }
  void set_has_initializer(bool has_initializer) const {
    raw_ptr()->has_initializer_ = has_initializer;
  }

  // Constructs getter and setter names for fields and vice versa.
  static RawString* GetterName(const String& field_name);
  static RawString* GetterSymbol(const String& field_name);
  static RawString* SetterName(const String& field_name);
  static RawString* SetterSymbol(const String& field_name);
  static RawString* NameFromGetter(const String& getter_name);
  static RawString* NameFromSetter(const String& setter_name);

 private:
  void set_name(const String& value) const;
  void set_is_static(bool is_static) const {
    raw_ptr()->is_static_ = is_static;
  }
  void set_is_final(bool is_final) const {
    raw_ptr()->is_final_ = is_final;
  }
  void set_token_index(intptr_t token_index) const {
    raw_ptr()->token_index_ = token_index;
  }
  static RawField* New();

  HEAP_OBJECT_IMPLEMENTATION(Field, Object);
  friend class Class;
};


class TokenStream : public Object {
 public:
  inline intptr_t Length() const;

  inline Token::Kind KindAt(intptr_t index) const;

  void SetTokenAt(intptr_t index, Token::Kind kind, const String& literal);

  RawObject* LiteralAt(intptr_t index) const {
    return *EntryAddr(index, RawTokenStream::kLiteralEntry);
  }

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawTokenStream) == OFFSET_OF(RawTokenStream, data_));
    return 0;
  }
  static intptr_t InstanceSize(intptr_t len) {
    return RoundedAllocationSize(
        sizeof(RawTokenStream) +
            (len * RawTokenStream::kNumberOfEntries * kWordSize));
  }
  static intptr_t StreamLength(intptr_t len) {
    return (len * RawTokenStream::kNumberOfEntries);
  }

  static RawTokenStream* New(intptr_t length);
  static RawTokenStream* New(const Scanner::GrowableTokenStream& tokens);

 private:
  void SetLength(intptr_t value) const;

  RawObject** EntryAddr(intptr_t index, intptr_t entry_offset) const {
    ASSERT((index >=0) && (index < Length()));
    intptr_t data_index =
        (index * RawTokenStream::kNumberOfEntries) + entry_offset;
    return &raw_ptr()->data_[data_index];
  }

  RawSmi** SmiAddr(intptr_t index, intptr_t entry_offset) const {
    return reinterpret_cast<RawSmi**>(EntryAddr(index, entry_offset));
  }

  HEAP_OBJECT_IMPLEMENTATION(TokenStream, Object);
  friend class Class;
};


class Script : public Object {
 public:
  RawString* url() const { return raw_ptr()->url_; }
  RawString* source() const { return raw_ptr()->source_; }
  RawScript::Kind kind() const { return raw_ptr()->kind_; }

  RawTokenStream* tokens() const { return raw_ptr()->tokens_; }

  void Tokenize(const String& private_key) const;

  RawString* GetLine(intptr_t line_number) const;

  RawString* GetSnippet(intptr_t from_line,
                        intptr_t from_column,
                        intptr_t to_line,
                        intptr_t to_column) const;

  void GetTokenLocation(intptr_t token_index,
                        intptr_t* line, intptr_t* column) const;

  intptr_t TokenIndexAtLine(intptr_t line_number) const;

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawScript));
  }

  static RawScript* New(const String& url,
                        const String& source,
                        RawScript::Kind kind);

 private:
  void set_url(const String& value) const;
  void set_source(const String& value) const;
  void set_kind(RawScript::Kind value) const;
  void set_tokens(const TokenStream& value) const;
  static RawScript* New();

  HEAP_OBJECT_IMPLEMENTATION(Script, Object);
  friend class Class;
};


class DictionaryIterator : public ValueObject {
 public:
  explicit DictionaryIterator(const Library& library);

  bool HasNext() const { return next_ix_ < size_; }

  // Returns next non-null raw object.
  RawObject* GetNext();

 private:
  void MoveToNextObject();

  const Array& array_;
  const int size_;  // Number of elements to iterate over.
  int next_ix_;  // Index of next element.

  friend class ClassDictionaryIterator;
  DISALLOW_COPY_AND_ASSIGN(DictionaryIterator);
};


class ClassDictionaryIterator : public DictionaryIterator {
 public:
  explicit ClassDictionaryIterator(const Library& library);

  // Returns a non-null raw class.
  RawClass* GetNextClass();

 private:
  void MoveToNextClass();

  DISALLOW_COPY_AND_ASSIGN(ClassDictionaryIterator);
};


class Library : public Object {
 public:
  RawString* name() const { return raw_ptr()->name_; }
  void SetName(const String& name) const;

  RawString* url() const { return raw_ptr()->url_; }
  RawString* private_key() const { return raw_ptr()->private_key_; }
  bool LoadNotStarted() const {
    return raw_ptr()->load_state_ == RawLibrary::kAllocated;
  }
  bool LoadInProgress() const {
    return raw_ptr()->load_state_ == RawLibrary::kLoadInProgress;
  }
  void SetLoadInProgress() const;
  bool Loaded() const { return raw_ptr()->load_state_ == RawLibrary::kLoaded; }
  void SetLoaded() const;
  bool LoadError() const {
    return raw_ptr()->load_state_ == RawLibrary::kLoadError;
  }
  void SetLoadError() const;

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawLibrary));
  }

  static RawLibrary* New(const String& url);

  // Library scope name dictionary.
  void AddClass(const Class& cls) const;
  void AddObject(const Object& obj, const String& name) const;
  RawObject* LookupObject(const String& name) const;
  RawClass* LookupClass(const String& name) const;
  RawObject* LookupLocalObject(const String& name) const;
  RawClass* LookupLocalClass(const String& name) const;
  RawScript* LookupScript(const String& url) const;
  RawArray* LoadedScripts() const;

  void AddAnonymousClass(const Class& cls) const;

  // Library imports.
  void AddImport(const Library& library) const;
  RawLibrary* LookupImport(const String& url) const;

  RawFunction* LookupFunctionInSource(const String& script_url,
                                      intptr_t line_number) const;
  RawFunction* LookupFunctionInScript(const Script& script,
                                      intptr_t token_index) const;

  // Resolving native methods for script loaded in the library.
  Dart_NativeEntryResolver native_entry_resolver() const {
    return raw_ptr()->native_entry_resolver_;
  }
  void set_native_entry_resolver(Dart_NativeEntryResolver value) const {
    raw_ptr()->native_entry_resolver_ = value;
  }

  RawString* PrivateName(const char* name);

  void Register() const;

  RawLibrary* next_registered() const { return raw_ptr()->next_registered_; }

  static RawLibrary* LookupLibrary(const String& url);
  static RawString* CheckForDuplicateDefinition();
  static bool IsKeyUsed(intptr_t key);

  static void InitCoreLibrary(Isolate* isolate);
  static RawLibrary* CoreLibrary();
  static RawLibrary* CoreImplLibrary();
  static void InitNativeWrappersLibrary(Isolate* isolate);
  static RawLibrary* NativeWrappersLibrary();

  // Eagerly compile all classes and functions in the library.
  static RawError* CompileAll();

 private:
  static const int kInitialImportsCapacity = 4;
  static const int kImportsCapacityIncrement = 8;
  static const int kInitialImportedIntoCapacity = 1;
  static const int kImportedIntoCapacityIncrement = 2;
  static RawLibrary* New();

  intptr_t num_imports() const { return raw_ptr()->num_imports_; }
  void set_num_imports(intptr_t value) const {
    raw_ptr()->num_imports_ = value;
  }
  intptr_t num_imported_into() const { return raw_ptr()->num_imported_into_; }
  void set_num_imported_into(intptr_t value) const {
    raw_ptr()->num_imported_into_ = value;
  }
  RawArray* imports() const { return raw_ptr()->imports_; }
  RawArray* imported_into() const { return raw_ptr()->imported_into_; }
  RawArray* loaded_scripts() const { return raw_ptr()->loaded_scripts_; }
  RawArray* dictionary() const { return raw_ptr()->dictionary_; }
  void InitClassDictionary() const;
  void InitImportList() const;
  void InitImportedIntoList() const;
  void GrowDictionary(const Array& dict, intptr_t dict_size) const;
  static RawLibrary* NewLibraryHelper(const String& url,
                                      bool import_core_lib);
  void AddImportedInto(const Library& library) const;
  RawObject* LookupObjectFiltered(const String& name,
                                  const Library& filter_lib) const;
  RawLibrary* LookupObjectInImporter(const String& name) const;
  RawString* DuplicateDefineErrorString(const String& entry_name,
                                        const Library& conflicting_lib) const;
  RawString* FindDuplicateDefinition(Library* conflicting_lib) const;

  HEAP_OBJECT_IMPLEMENTATION(Library, Object);
  friend class Class;
  friend class DictionaryIterator;
  friend class Debugger;
  friend class Isolate;
};


class LibraryPrefix : public Object {
 public:
  RawString* name() const { return raw_ptr()->name_; }
  RawLibrary* library() const { return raw_ptr()->library_; }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawLibraryPrefix));
  }

  static RawLibraryPrefix* New(const String& name, const Library& lib);

 private:
  void set_name(const String& value) const;
  void set_library(const Library& value) const;
  static RawLibraryPrefix* New();

  HEAP_OBJECT_IMPLEMENTATION(LibraryPrefix, Object);
  friend class Class;
  friend class Isolate;
};


class Instructions : public Object {
 public:
  intptr_t size() const { return raw_ptr()->size_; }
  RawCode* code() const { return raw_ptr()->code_; }

  uword EntryPoint() const {
    return reinterpret_cast<uword>(raw_ptr()) + HeaderSize();
  }

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawInstructions) == OFFSET_OF(RawInstructions, data_));
    return 0;
  }

  static intptr_t InstanceSize(intptr_t size) {
    intptr_t instructions_size = Utils::RoundUp(size,
                                                OS::PreferredCodeAlignment());
    intptr_t result = instructions_size + HeaderSize();
    ASSERT(result % OS::PreferredCodeAlignment() == 0);
    return result;
  }

  static intptr_t HeaderSize() {
    intptr_t alignment = OS::PreferredCodeAlignment();
    return Utils::RoundUp(sizeof(RawInstructions), alignment);
  }

  static RawInstructions* FromEntryPoint(uword entry_point) {
    return reinterpret_cast<RawInstructions*>(
        entry_point - HeaderSize() + kHeapObjectTag);
  }

 private:
  void set_size(intptr_t size) const {
    raw_ptr()->size_ = size;
  }
  void set_code(RawCode* code) {
    raw_ptr()->code_ = code;
  }

  // New is a private method as RawInstruction and RawCode objects should
  // only be created using the Code::FinalizeCode method. This method creates
  // the RawInstruction and RawCode objects, sets up the pointer offsets
  // and links the two in a GC safe manner.
  static RawInstructions* New(intptr_t size);

  HEAP_OBJECT_IMPLEMENTATION(Instructions, Object);
  friend class Code;
  friend class Class;
};


class LocalVarDescriptors : public Object {
 public:
  intptr_t Length() const;

  RawString* GetName(intptr_t var_index) const;
  void GetScopeInfo(intptr_t var_index,
                    intptr_t* scope_id,
                    intptr_t* begin_token_pos,
                    intptr_t* end_token_pos) const;
  intptr_t GetSlotIndex(intptr_t var_index) const;

  void SetVar(intptr_t var_index,
              const String& name,
              intptr_t stack_slot,
              intptr_t scope_id,
              intptr_t begin_pos,
              intptr_t end_pos) const;

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawLocalVarDescriptors) ==
        OFFSET_OF(RawLocalVarDescriptors, data_));
    return 0;
  }
  static intptr_t InstanceSize(intptr_t len) {
    return RoundedAllocationSize(
        sizeof(RawLocalVarDescriptors) +
        (len * sizeof(RawLocalVarDescriptors::VarInfo)));
  }

  static RawLocalVarDescriptors* New(intptr_t num_variables);

 private:
  HEAP_OBJECT_IMPLEMENTATION(LocalVarDescriptors, Object);
  friend class Class;
};


class PcDescriptors : public Object {
 public:
  enum Kind {
    kDeopt = 0,  // Deoptimization cotinuation point.
    kPatchCode,  // Buffer for patching code entry.
    kIcCall,     // IC call.
    kOther
  };

  intptr_t Length() const;

  uword PC(intptr_t index) const;
  PcDescriptors::Kind DescriptorKind(intptr_t index) const;
  const char* KindAsStr(intptr_t index) const;
  intptr_t NodeId(intptr_t index) const;
  intptr_t TokenIndex(intptr_t index) const;
  intptr_t TryIndex(intptr_t index) const;

  void AddDescriptor(intptr_t index,
                     uword pc,
                     PcDescriptors::Kind kind,
                     intptr_t node_id,
                     intptr_t token_index,
                     intptr_t try_index) const {
    SetPC(index, pc);
    SetKind(index, kind);
    SetNodeId(index, node_id);
    SetTokenIndex(index, token_index);
    SetTryIndex(index, try_index);
  }

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawPcDescriptors) == OFFSET_OF(RawPcDescriptors, data_));
    return 0;
  }
  static intptr_t InstanceSize(intptr_t len) {
    return RoundedAllocationSize(
        sizeof(RawPcDescriptors) + (len * kNumberOfEntries * kWordSize));
  }

  static RawPcDescriptors* New(intptr_t num_descriptors);

  // We would have a VisitPointers function here to traverse the
  // pc descriptors table to visit objects if any in the table.

 private:
  // Describes the layout of PC descriptor data.
  enum {
    kPcEntry = 0,      // PC value of the descriptor, unique.
    kKindEntry,
    kNodeIdEntry,      // AST node id.
    kTokenIndexEntry,  // Token position in source of PC.
    kTryIndexEntry,    // Try block index of PC.
    // We would potentially be adding other objects here like
    // pointer maps for optimized functions, local variables information  etc.
    kNumberOfEntries
  };

  void SetPC(intptr_t index, uword value) const;
  void SetKind(intptr_t index, PcDescriptors::Kind kind) const;
  void SetNodeId(intptr_t index, intptr_t value) const;
  void SetTokenIndex(intptr_t index, intptr_t value) const;
  void SetTryIndex(intptr_t index, intptr_t value) const;

  void SetLength(intptr_t value) const;

  intptr_t* EntryAddr(intptr_t index, intptr_t entry_offset) const {
    ASSERT((index >=0) && (index < Length()));
    intptr_t data_index = (index * kNumberOfEntries) + entry_offset;
    return &raw_ptr()->data_[data_index];
  }
  RawSmi** SmiAddr(intptr_t index, intptr_t entry_offset) const {
    return reinterpret_cast<RawSmi**>(EntryAddr(index, entry_offset));
  }

  HEAP_OBJECT_IMPLEMENTATION(PcDescriptors, Object);
  friend class Class;
};


class ExceptionHandlers : public Object {
 public:
  intptr_t Length() const;

  intptr_t TryIndex(intptr_t index) const;
  intptr_t HandlerPC(intptr_t index) const;

  void SetHandlerEntry(intptr_t index,
                       intptr_t try_index,
                       intptr_t handler_pc) const {
    SetTryIndex(index, try_index);
    SetHandlerPC(index, handler_pc);
  }

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawExceptionHandlers) == OFFSET_OF(RawExceptionHandlers,
                                                     data_));
    return 0;
  }
  static intptr_t InstanceSize(intptr_t len) {
    return RoundedAllocationSize(sizeof(RawExceptionHandlers) +
                                 (len * kNumberOfEntries * kWordSize));
  }

  static RawExceptionHandlers* New(intptr_t num_handlers);

  // We would have a VisitPointers function here to traverse the
  // exception handler table to visit objects if any in the table.

 private:
  // Describes the layout of exception handler data.
  enum {
    kTryIndexEntry = 0,  // Try block index associated with handler.
    kHandlerPcEntry,  // PC value of handler.
    kNumberOfEntries
  };

  void SetTryIndex(intptr_t index, intptr_t value) const;
  void SetHandlerPC(intptr_t index, intptr_t value) const;

  void SetLength(intptr_t value) const;

  intptr_t* EntryAddr(intptr_t index, intptr_t entry_offset) const {
    ASSERT((index >=0) && (index < Length()));
    intptr_t data_index = (index * kNumberOfEntries) + entry_offset;
    return &raw_ptr()->data_[data_index];
  }

  HEAP_OBJECT_IMPLEMENTATION(ExceptionHandlers, Object);
  friend class Class;
};


class Code : public Object {
 public:
  RawInstructions* instructions() const { return raw_ptr()->instructions_; }
  static intptr_t instructions_offset() {
    return OFFSET_OF(RawCode, instructions_);
  }
  intptr_t pointer_offsets_length() const {
    return raw_ptr()->pointer_offsets_length_;
  }
  bool is_optimized() const {
    return (raw_ptr()->is_optimized_ == 1);
  }
  void set_is_optimized(bool value) const {
    raw_ptr()->is_optimized_ = value ? 1 : 0;
  }
  uword EntryPoint() const {
    const Instructions& instr = Instructions::Handle(instructions());
    return instr.EntryPoint();
  }
  intptr_t Size() const {
    const Instructions& instr = Instructions::Handle(instructions());
    return instr.size();
  }

  RawPcDescriptors* pc_descriptors() const {
    return raw_ptr()->pc_descriptors_;
  }
  void set_pc_descriptors(const PcDescriptors& descriptors) const {
    StorePointer(&raw_ptr()->pc_descriptors_, descriptors.raw());
  }

  RawLocalVarDescriptors* var_descriptors() const {
    return raw_ptr()->var_descriptors_;
  }
  void set_var_descriptors(const LocalVarDescriptors& value) const {
    StorePointer(&raw_ptr()->var_descriptors_, value.raw());
  }

  // See class ICData for interpretation of the 'ic_data_' array.
  RawArray* ic_data() const;
  void set_ic_data(const Array& ic_data) const;

  RawExceptionHandlers* exception_handlers() const {
    return raw_ptr()->exception_handlers_;
  }
  void set_exception_handlers(const ExceptionHandlers& handlers) const {
    StorePointer(&raw_ptr()->exception_handlers_, handlers.raw());
  }

  RawFunction* function() const {
    return raw_ptr()->function_;
  }
  void set_function(const Function& function) const {
    StorePointer(&raw_ptr()->function_, function.raw());
  }

  // We would have a VisitPointers function here to traverse all the
  // embedded objects in the instructions using pointer_offsets.

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawCode) == OFFSET_OF(RawCode, data_));
    return 0;
  }
  static intptr_t InstanceSize(intptr_t pointer_offsets_length) {
    return RoundedAllocationSize(
        sizeof(RawCode) + (pointer_offsets_length * kEntrySize));
  }
  static RawCode* FinalizeCode(const char* name, Assembler* assembler);

  int32_t GetPointerOffsetAt(int index) const {
    return *PointerOffsetAddrAt(index);
  }
  intptr_t GetTokenIndexOfPC(uword pc) const;

  // Find pc of patch code buffer. Return 0 if not found.
  uword GetPatchCodePc() const;

  uword GetDeoptPcAtNodeId(intptr_t node_id) const;

  // Returns true if there is an object in the code between 'start_offset'
  // (inclusive) and 'end_offset' (exclusive).
  bool ObjectExistInArea(intptr_t start_offest, intptr_t end_offset) const;

  // Each (*node_ids)[n] has a an extracted ic data array (*arrays)[n].
  void ExtractIcDataArraysAtCalls(GrowableArray<intptr_t>* node_ids,
                                  GrowableArray<const Array*>* arrays) const;

 private:
  static const intptr_t kEntrySize = sizeof(int32_t);  // NOLINT

  void set_instructions(RawInstructions* instructions) {
    raw_ptr()->instructions_ = instructions;
  }
  void set_pointer_offsets_length(intptr_t value) {
    ASSERT(value >= 0);
    raw_ptr()->pointer_offsets_length_ = value;
  }
  int32_t* PointerOffsetAddrAt(int index) const {
    ASSERT(index >= 0);
    ASSERT(index < pointer_offsets_length());
    // TODO(iposva): Unit test is missing for this functionality.
    return &raw_ptr()->data_[index];
  }
  void SetPointerOffsetAt(int index, int32_t offset_in_instructions) {
    *PointerOffsetAddrAt(index) = offset_in_instructions;
  }

  // New is a private method as RawInstruction and RawCode objects should
  // only be created using the Code::FinalizeCode method. This method creates
  // the RawInstruction and RawCode objects, sets up the pointer offsets
  // and links the two in a GC safe manner.
  static RawCode* New(int pointer_offsets_length);

  HEAP_OBJECT_IMPLEMENTATION(Code, Object);
  friend class Class;
};


class Context : public Object {
 public:
  RawContext* parent() const { return raw_ptr()->parent_; }
  void set_parent(const Context& parent) const {
    ASSERT(parent.isolate() == Isolate::Current());
    StorePointer(&raw_ptr()->parent_, parent.raw());
  }
  static intptr_t parent_offset() { return OFFSET_OF(RawContext, parent_); }

  Isolate* isolate() const { return raw_ptr()->isolate_; }
  static intptr_t isolate_offset() { return OFFSET_OF(RawContext, isolate_); }

  intptr_t num_variables() const { return raw_ptr()->num_variables_; }
  static intptr_t num_variables_offset() {
    return OFFSET_OF(RawContext, num_variables_);
  }

  RawInstance* At(intptr_t context_index) const {
    return *InstanceAddr(context_index);
  }
  inline void SetAt(intptr_t context_index, const Instance& value) const;

  static intptr_t variable_offset(intptr_t context_index) {
    return OFFSET_OF(RawContext, data_[context_index]);
  }

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawContext) == OFFSET_OF(RawContext, data_));
    return 0;
  }

  static intptr_t InstanceSize(intptr_t num_variables) {
    return RoundedAllocationSize(sizeof(RawContext) +
                                 (num_variables * kWordSize));
  }

  static RawContext* New(intptr_t num_variables,
                         Heap::Space space = Heap::kNew);

 private:
  RawInstance** InstanceAddr(intptr_t context_index) const {
    ASSERT((context_index >= 0) && (context_index < num_variables()));
    return &raw_ptr()->data_[context_index];
  }

  void set_isolate(Isolate* isolate) const {
    raw_ptr()->isolate_ = isolate;
  }

  void set_num_variables(intptr_t num_variables) const {
    raw_ptr()->num_variables_ = num_variables;
  }

  HEAP_OBJECT_IMPLEMENTATION(Context, Object);
  friend class Class;
};


// The ContextScope class makes it possible to delay the compilation of a local
// function until it is invoked. A ContextScope instance collects the local
// variables that are referenced by the local function to be compiled and that
// belong to the outer scopes, that is, to the local scopes of (possibly nested)
// functions enclosing the local function. Each captured variable is represented
// by its token position in the source, its name, its type, its allocation index
// in the context, and its context level. The function nesting level and loop
// nesting level are not preserved, since they are only used until the context
// level is assigned.
class ContextScope : public Object {
 public:
  intptr_t num_variables() const { return raw_ptr()->num_variables_; }

  intptr_t TokenIndexAt(intptr_t scope_index) const;
  void SetTokenIndexAt(intptr_t scope_index, intptr_t token_index) const;

  RawString* NameAt(intptr_t scope_index) const;
  void SetNameAt(intptr_t scope_index, const String& name) const;

  bool IsFinalAt(intptr_t scope_index) const;
  void SetIsFinalAt(intptr_t scope_index, bool is_const) const;

  RawAbstractType* TypeAt(intptr_t scope_index) const;
  void SetTypeAt(intptr_t scope_index, const AbstractType& type) const;

  intptr_t ContextIndexAt(intptr_t scope_index) const;
  void SetContextIndexAt(intptr_t scope_index, intptr_t context_index) const;

  intptr_t ContextLevelAt(intptr_t scope_index) const;
  void SetContextLevelAt(intptr_t scope_index, intptr_t context_level) const;

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawContextScope) == OFFSET_OF(RawContextScope, data_));
    return 0;
  }

  static intptr_t InstanceSize(intptr_t num_variables) {
    return RoundedAllocationSize(sizeof(RawContextScope) +
        (num_variables * sizeof(RawContextScope::VariableDesc)));
  }

  static RawContextScope* New(intptr_t num_variables);

 private:
  void set_num_variables(intptr_t num_variables) const {
    raw_ptr()->num_variables_ = num_variables;
  }

  RawContextScope::VariableDesc* VariableDescAddr(intptr_t index) const {
    ASSERT((index >= 0) && (index < num_variables()));
    uword raw_addr = reinterpret_cast<uword>(raw_ptr());
    raw_addr += sizeof(RawContextScope) +
        (index * sizeof(RawContextScope::VariableDesc));
    return reinterpret_cast<RawContextScope::VariableDesc*>(raw_addr);
  }

  HEAP_OBJECT_IMPLEMENTATION(ContextScope, Object);
  friend class Class;
};


class Error : public Object {
 public:
  virtual const char* ToErrorCString() const;

 private:
  HEAP_OBJECT_IMPLEMENTATION(Error, Object);
};


class ApiError : public Error {
 public:
  RawString* message() const { return raw_ptr()->message_; }
  static intptr_t message_offset() {
    return OFFSET_OF(RawApiError, message_);
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawApiError));
  }

  static RawApiError* New(const String& message,
                          Heap::Space space = Heap::kNew);

  virtual const char* ToErrorCString() const;

 private:
  void set_message(const String& message) const;

  HEAP_OBJECT_IMPLEMENTATION(ApiError, Error);
  friend class Class;
};


class LanguageError : public Error {
 public:
  RawString* message() const { return raw_ptr()->message_; }
  static intptr_t message_offset() {
    return OFFSET_OF(RawLanguageError, message_);
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawLanguageError));
  }

  static RawLanguageError* New(const String& message,
                               Heap::Space space = Heap::kNew);

  virtual const char* ToErrorCString() const;

 private:
  void set_message(const String& message) const;

  HEAP_OBJECT_IMPLEMENTATION(LanguageError, Error);
  friend class Class;
};


class UnhandledException : public Error {
 public:
  RawInstance* exception() const { return raw_ptr()->exception_; }
  static intptr_t exception_offset() {
    return OFFSET_OF(RawUnhandledException, exception_);
  }

  RawInstance* stacktrace() const { return raw_ptr()->stacktrace_; }
  static intptr_t stacktrace_offset() {
    return OFFSET_OF(RawUnhandledException, stacktrace_);
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawUnhandledException));
  }

  static RawUnhandledException* New(const Instance& exception,
                                    const Instance& stacktrace,
                                    Heap::Space space = Heap::kNew);

  virtual const char* ToErrorCString() const;

 private:
  void set_exception(const Instance& exception) const;
  void set_stacktrace(const Instance& stacktrace) const;

  HEAP_OBJECT_IMPLEMENTATION(UnhandledException, Error);
  friend class Class;
};


class UnwindError : public Error {
 public:
  RawString* message() const { return raw_ptr()->message_; }
  static intptr_t message_offset() {
    return OFFSET_OF(RawUnwindError, message_);
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawUnwindError));
  }

  static RawUnwindError* New(const String& message,
                             Heap::Space space = Heap::kNew);

  virtual const char* ToErrorCString() const;

 private:
  void set_message(const String& message) const;

  HEAP_OBJECT_IMPLEMENTATION(UnwindError, Error);
  friend class Class;
};


// Instance is the base class for all instance objects (aka the Object class
// in Dart source code.
class Instance : public Object {
 public:
  virtual bool Equals(const Instance& other) const;
  virtual RawInstance* Canonicalize() const;

  RawObject* GetField(const Field& field) const {
    return *FieldAddr(field);
  }

  void SetField(const Field& field, const Object& value) const {
    StorePointer(FieldAddr(field), value.raw());
  }

  RawType* GetType() const;

  virtual RawAbstractTypeArguments* GetTypeArguments() const;
  virtual void SetTypeArguments(const AbstractTypeArguments& value) const;

  // Check if this instance is an instance of the given type.
  bool IsInstanceOf(const AbstractType& type,
                    const AbstractTypeArguments& type_instantiator) const {
    return TestType(kIsSubtypeOf, type, type_instantiator);
  }

  // Check if this instance is assignable to the given type.
  bool IsAssignableTo(const AbstractType& type,
                      const AbstractTypeArguments& type_instantiator) const {
    return TestType(kIsAssignableTo, type, type_instantiator);
  }

  bool IsValidNativeIndex(int index) const;

  intptr_t GetNativeField(int index) const {
    return *NativeFieldAddr(index);
  }

  void SetNativeField(int index, intptr_t value) const {
    *NativeFieldAddr(index) = value;
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawInstance));
  }

  static RawInstance* New(const Class& cls, Heap::Space space = Heap::kNew);

 private:
  RawObject** FieldAddrAtOffset(intptr_t offset) const {
    ASSERT(IsValidFieldOffset(offset));
    return reinterpret_cast<RawObject**>(raw_value() - kHeapObjectTag + offset);
  }
  RawObject** FieldAddr(const Field& field) const {
    return FieldAddrAtOffset(field.Offset());
  }
  intptr_t* NativeFieldAddr(int index) const {
    ASSERT(IsValidNativeIndex(index));
    return reinterpret_cast<intptr_t*>((raw_value() - kHeapObjectTag)
                                       + (index * kWordSize)
                                       + sizeof(RawObject));
  }
  void SetFieldAtOffset(intptr_t offset, const Object& value) const {
    StorePointer(FieldAddrAtOffset(offset), value.raw());
  }
  bool IsValidFieldOffset(int offset) const;

  // Check the subtype or assignability relationship between the type of this
  // instance and the given type.
  bool TestType(TypeTestKind test,
                const AbstractType& type,
                const AbstractTypeArguments& type_instantiator) const;

  // TODO(iposva): Determine if this gets in the way of Smi.
  HEAP_OBJECT_IMPLEMENTATION(Instance, Object);
  friend class Class;
};


class Number : public Instance {
 public:
  // TODO(iposva): Fill in a useful Number interface.
  virtual bool IsZero() const {
    // Number is an abstract class.
    UNREACHABLE();
    return false;
  }
  virtual bool IsNegative() const {
    // Number is an abstract class.
    UNREACHABLE();
    return false;
  }
  OBJECT_IMPLEMENTATION(Number, Instance);
};


class Integer : public Number {
 public:
  static RawInteger* New(const String& str);
  static RawInteger* New(int64_t value);

  virtual double AsDoubleValue() const;
  virtual int64_t AsInt64Value() const;

  // Returns 0, -1 or 1.
  virtual int CompareWith(const Integer& other) const;

  OBJECT_IMPLEMENTATION(Integer, Number);
};


class Smi : public Integer {
 public:
  // Smi value range is from -(2^N) to (2^N)-1.
  // N=30 (32-bit build) or N=62 (64-bit build).
  static const intptr_t kBits = kBitsPerWord - 2;
  static const intptr_t kMaxValue = (static_cast<intptr_t>(1) << kBits) - 1;
  static const intptr_t kMinValue =  -(static_cast<intptr_t>(1) << kBits);

  intptr_t Value() const {
    return ValueFromRaw(raw_value());
  }

  virtual bool Equals(const Instance& other) const;
  virtual bool IsZero() const { return Value() == 0; }
  virtual bool IsNegative() const { return Value() < 0; }
  // Smi values are implicitly canonicalized.
  virtual RawInstance* Canonicalize() const {
    return reinterpret_cast<RawSmi*>(raw_value());
  }

  virtual double AsDoubleValue() const;
  virtual int64_t AsInt64Value() const;

  virtual int CompareWith(const Integer& other) const;

  static intptr_t InstanceSize() { return 0; }

  static RawSmi* New(intptr_t value) {
    word raw_smi = (value << kSmiTagShift) | kSmiTag;
    ASSERT(ValueFromRaw(raw_smi) == value);
    return reinterpret_cast<RawSmi*>(raw_smi);
  }

  static RawClass* Class();

  static intptr_t Value(RawSmi* raw_smi) {
    return ValueFromRaw(reinterpret_cast<uword>(raw_smi));
  }

  static intptr_t RawValue(intptr_t value) {
    return reinterpret_cast<intptr_t>(New(value));
  }

  static bool IsValid(intptr_t value);
  static bool IsValid64(int64_t value);

 private:
  static intptr_t ValueFromRaw(uword raw_value) {
    intptr_t value = raw_value;
    ASSERT((value & kSmiTagMask) == kSmiTag);
    return (value >> kSmiTagShift);
  }
  static cpp_vtable handle_vtable_;

  OBJECT_IMPLEMENTATION(Smi, Integer);
  friend class Object;
  friend class Class;
};


class Mint : public Integer {
 public:
  static const intptr_t kBits = 63;  // 64-th bit is sign.
  static const int64_t kMaxValue =
      static_cast<int64_t>(DART_2PART_UINT64_C(0x7FFFFFFF, FFFFFFFF));
  static const int64_t kMinValue =
      static_cast<int64_t>(DART_2PART_UINT64_C(0x80000000, 00000000));

  int64_t value() const {
    return raw_ptr()->value_;
  }
  static intptr_t value_offset() { return OFFSET_OF(RawMint, value_); }

  virtual bool IsZero() const {
    return value() == 0;
  }
  virtual bool IsNegative() const {
    return value() < 0;
  }

  virtual bool Equals(const Instance& other) const;

  virtual double AsDoubleValue() const;
  virtual int64_t AsInt64Value() const;

  virtual int CompareWith(const Integer& other) const;

  static RawMint* New(int64_t value, Heap::Space space = Heap::kNew);
  static RawMint* NewCanonical(int64_t value);

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawMint));
  }

 private:
  void set_value(int64_t value) const;

  HEAP_OBJECT_IMPLEMENTATION(Mint, Integer);
  friend class Class;
};


class Bigint : public Integer {
 public:
  virtual bool IsZero() const;
  virtual bool IsNegative() const;

  virtual bool Equals(const Instance& other) const;

  virtual double AsDoubleValue() const;
  virtual int64_t AsInt64Value() const;

  virtual int CompareWith(const Integer& other) const;

  static intptr_t InstanceSize(const BIGNUM* bn) {
    // Danger Will Robinson! Use of OpenSSL internals!
    return RoundedAllocationSize(sizeof(RawBigint)
                                 + sizeof(BN_ULONG) * bn->top);
  }
  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawBigint) == OFFSET_OF(RawBigint, data_));
    return 0;
  }

  static RawBigint* New(const BIGNUM* bn, Heap::Space space = Heap::kNew);

  static RawBigint* New(const String& str, Heap::Space space = Heap::kNew);
  static RawBigint* New(int64_t value, Heap::Space space = Heap::kNew);

 private:
  void SetSign(bool is_negative) const;

  void ToggleSign() const {
    BIGNUM* bn = MutableBNAddr();
    // Danger Will Robinson! Use of OpenSSL internals!
    // FIXME(benl): can be changed to use BN_set_negative() on more
    // recent OpenSSL releases (> 1.0.0).
    SetSign(!bn->neg);
  }

  BIGNUM* MutableBNAddr() const {
    // Fix up internals as we may have been moved.
    raw_ptr()->bn_.d = BNMemory();

    return &raw_ptr()->bn_;
  }
  const BIGNUM* BNAddr() const { return MutableBNAddr(); }
  BN_ULONG* BNMemory() const {
    return &raw_ptr()->data_[0];
  }

  int NumberOfBits() const { return BN_num_bits(BNAddr()); }
  bool IsBitSet(intptr_t bit) const { return Bit(bit) == 1; }
  int Bit(intptr_t bit) const { return BN_is_bit_set(BNAddr(), bit); }

  HEAP_OBJECT_IMPLEMENTATION(Bigint, Integer);
  friend class Class;
  friend class BigintOperations;
};


class Double : public Number {
 public:
  double value() const {
    return raw_ptr()->value_;
  }

  bool EqualsToDouble(double value) const;
  virtual bool Equals(const Instance& other) const;

  static RawDouble* New(double d, Heap::Space space = Heap::kNew);

  static RawDouble* New(const String& str, Heap::Space space = Heap::kNew);

  // Returns a canonical double object allocated in the old gen space.
  static RawDouble* NewCanonical(double d);

  // Returns a canonical double object (allocated in the old gen space) or
  // Double::null() if str points to a string that does not convert to a
  // double value.
  static RawDouble* NewCanonical(const String& str);

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawDouble));
  }

  static intptr_t value_offset() { return OFFSET_OF(RawDouble, value_); }

 private:
  void set_value(double value) const;

  HEAP_OBJECT_IMPLEMENTATION(Double, Number);
  friend class Class;
};


// String may not be '\0' terminated.
class String : public Instance {
 public:
  typedef void (*PeerFinalizer)(void *peer);

  // We use 30 bits for the hash code so that we consistently use a
  // 32bit Smi representation for the hash code on all architectures.
  static const intptr_t kHashBits = 30;

  static const intptr_t kOneByteChar = 1;
  static const intptr_t kTwoByteChar = 2;
  static const intptr_t kFourByteChar = 4;

  intptr_t Length() const { return Smi::Value(raw_ptr()->length_); }
  static intptr_t length_offset() { return OFFSET_OF(RawString, length_); }

  virtual intptr_t Hash() const;
  static intptr_t hash_offset() { return OFFSET_OF(RawString, hash_); }
  static intptr_t Hash(const String& str, intptr_t begin_index, intptr_t len);
  static intptr_t Hash(const uint8_t* characters, intptr_t len);
  static intptr_t Hash(const uint16_t* characters, intptr_t len);
  static intptr_t Hash(const uint32_t* characters, intptr_t len);

  virtual int32_t CharAt(intptr_t index) const;

  virtual intptr_t CharSize() const;

  bool Equals(const String& str) const {
    if (raw() == str.raw()) {
      return true;  // Both handles point to the same raw instance.
    }
    if (str.IsNull()) {
      return false;
    }
    return Equals(str, 0, str.Length());
  }
  bool Equals(const String& str, intptr_t begin_index, intptr_t len) const;
  bool Equals(const char* str) const;
  bool Equals(const uint8_t* characters, intptr_t len) const;
  bool Equals(const uint16_t* characters, intptr_t len) const;
  bool Equals(const uint32_t* characters, intptr_t len) const;

  virtual bool Equals(const Instance& other) const;

  intptr_t CompareTo(const String& other) const;

  bool StartsWith(const String& other) const;

  virtual RawInstance* Canonicalize() const;

  bool IsSymbol() const { return raw()->IsCanonical(); }

  virtual bool IsExternal() const { return false; }
  virtual void* GetPeer() const {
    UNREACHABLE();
    return NULL;
  }

  static RawString* New(const char* str, Heap::Space space = Heap::kNew);
  static RawString* New(const uint8_t* characters,
                        intptr_t len,
                        Heap::Space space = Heap::kNew);
  static RawString* New(const uint16_t* characters,
                        intptr_t len,
                        Heap::Space space = Heap::kNew);
  static RawString* New(const uint32_t* characters,
                        intptr_t len,
                        Heap::Space space = Heap::kNew);
  static RawString* New(const String& str, Heap::Space space = Heap::kNew);

  static RawString* NewExternal(const uint8_t* characters,
                                intptr_t len,
                                void* peer,
                                PeerFinalizer callback,
                                Heap::Space = Heap::kNew);
  static RawString* NewExternal(const uint16_t* characters,
                                intptr_t len,
                                void* peer,
                                PeerFinalizer callback,
                                Heap::Space = Heap::kNew);
  static RawString* NewExternal(const uint32_t* characters,
                                intptr_t len,
                                void* peer,
                                PeerFinalizer callback,
                                Heap::Space = Heap::kNew);

  static void Copy(const String& dst,
                   intptr_t dst_offset,
                   const uint8_t* characters,
                   intptr_t len);
  static void Copy(const String& dst,
                   intptr_t dst_offset,
                   const uint16_t* characters,
                   intptr_t len);
  static void Copy(const String& dst,
                   intptr_t dst_offset,
                   const uint32_t* characters,
                   intptr_t len);
  static void Copy(const String& dst,
                   intptr_t dst_offset,
                   const String& src,
                   intptr_t src_offset,
                   intptr_t len);

  static RawString* Concat(const String& str1,
                           const String& str2,
                           Heap::Space space = Heap::kNew);
  static RawString* ConcatAll(const Array& strings,
                              Heap::Space space = Heap::kNew);

  static RawString* SubString(const String& str,
                              intptr_t begin_index,
                              Heap::Space space = Heap::kNew);
  static RawString* SubString(const String& str,
                              intptr_t begin_index,
                              intptr_t length,
                              Heap::Space space = Heap::kNew);

  static RawString* Transform(int32_t (*mapping)(int32_t ch),
                              const String& str,
                              Heap::Space space = Heap::kNew);

  static RawString* ToUpperCase(const String& str,
                                Heap::Space space = Heap::kNew);
  static RawString* ToLowerCase(const String& str,
                                Heap::Space space = Heap::kNew);

  static RawString* NewSymbol(const char* str);
  template<typename T>
  static RawString* NewSymbol(const T* characters, intptr_t len);
  static RawString* NewSymbol(const String& str);
  static RawString* NewSymbol(const String& str,
                              intptr_t begin_index,
                              intptr_t length);

 protected:
  bool HasHash() const {
    ASSERT(Smi::New(0) == NULL);
    return (raw_ptr()->hash_ != NULL);
  }

  void SetLength(intptr_t value) const {
    // This is only safe because we create a new Smi, which does not cause
    // heap allocation.
    raw_ptr()->length_ = Smi::New(value);
  }

  void SetHash(intptr_t value) const {
    // This is only safe because we create a new Smi, which does not cause
    // heap allocation.
    raw_ptr()->hash_ = Smi::New(value);
  }

  template<typename HandleType, typename ElementType>
  static void ReadFromImpl(SnapshotReader* reader,
                           HandleType* str_obj,
                           intptr_t len,
                           intptr_t tags);

  HEAP_OBJECT_IMPLEMENTATION(String, Instance);
};


class OneByteString : public String {
 public:
  virtual int32_t CharAt(intptr_t index) const {
    return *CharAddr(index);
  }

  virtual intptr_t CharSize() const {
    return kOneByteChar;
  }

  static intptr_t data_offset() { return OFFSET_OF(RawOneByteString, data_); }

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawOneByteString) == OFFSET_OF(RawOneByteString, data_));
    return 0;
  }

  static intptr_t InstanceSize(intptr_t len) {
    return RoundedAllocationSize(sizeof(RawOneByteString) + len);
  }

  static RawOneByteString* New(intptr_t len,
                               Heap::Space space);
  static RawOneByteString* New(const uint8_t* characters,
                               intptr_t len,
                               Heap::Space space);
  static RawOneByteString* New(const uint16_t* characters,
                               intptr_t len,
                               Heap::Space space);
  static RawOneByteString* New(const uint32_t* characters,
                               intptr_t len,
                               Heap::Space space);
  static RawOneByteString* New(const OneByteString& str,
                               Heap::Space space);

  static RawOneByteString* Concat(const String& str1,
                                  const String& str2,
                                  Heap::Space space);
  static RawOneByteString* ConcatAll(const Array& strings,
                                     intptr_t len,
                                     Heap::Space space);

  static RawOneByteString* Transform(int32_t (*mapping)(int32_t ch),
                                     const String& str,
                                     Heap::Space space);

 private:
  uint8_t* CharAddr(intptr_t index) const {
    // TODO(iposva): Determine if we should throw an exception here.
    ASSERT((index >= 0) && (index < Length()));
    return &raw_ptr()->data_[index];
  }

  HEAP_OBJECT_IMPLEMENTATION(OneByteString, String);
  friend class Class;
  friend class String;
};


class TwoByteString : public String {
 public:
  virtual int32_t CharAt(intptr_t index) const {
    return *CharAddr(index);
  }

  virtual intptr_t CharSize() const {
    return kTwoByteChar;
  }

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawTwoByteString) == OFFSET_OF(RawTwoByteString, data_));
    return 0;
  }

  static intptr_t InstanceSize(intptr_t len) {
    return RoundedAllocationSize(sizeof(RawTwoByteString) + (2 * len));
  }

  static RawTwoByteString* New(intptr_t len,
                               Heap::Space space);
  static RawTwoByteString* New(const uint16_t* characters,
                               intptr_t len,
                               Heap::Space space);
  static RawTwoByteString* New(const uint32_t* characters,
                               intptr_t len,
                               Heap::Space space);
  static RawTwoByteString* New(const TwoByteString& str,
                               Heap::Space space);

  static RawTwoByteString* Concat(const String& str1,
                                  const String& str2,
                                  Heap::Space space);
  static RawTwoByteString* ConcatAll(const Array& strings,
                                     intptr_t len,
                                     Heap::Space space);

  static RawTwoByteString* Transform(int32_t (*mapping)(int32_t ch),
                                     const String& str,
                                     Heap::Space space);

 private:
  uint16_t* CharAddr(intptr_t index) const {
    ASSERT((index >= 0) && (index < Length()));
    return &raw_ptr()->data_[index];
  }

  HEAP_OBJECT_IMPLEMENTATION(TwoByteString, String);
  friend class Class;
  friend class String;
};


class FourByteString : public String {
 public:
  virtual int32_t CharAt(intptr_t index) const {
    return *CharAddr(index);
  }

  virtual intptr_t CharSize() const {
    return kFourByteChar;
  }

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawFourByteString) == OFFSET_OF(RawFourByteString, data_));
    return 0;
  }

  static intptr_t InstanceSize(intptr_t len) {
    return RoundedAllocationSize(sizeof(RawFourByteString) + (4 * len));
  }

  static RawFourByteString* New(intptr_t len,
                                Heap::Space space);
  static RawFourByteString* New(const uint32_t* characters,
                                intptr_t len,
                                Heap::Space space);
  static RawFourByteString* New(const FourByteString& str,
                                Heap::Space space);

  static RawFourByteString* Concat(const String& str1,
                                   const String& str2,
                                   Heap::Space space);
  static RawFourByteString* ConcatAll(const Array& strings,
                                      intptr_t len,
                                      Heap::Space space);

  static RawFourByteString* Transform(int32_t (*mapping)(int32_t ch),
                                      const String& str,
                                      Heap::Space space);

 private:
  uint32_t* CharAddr(intptr_t index) const {
    ASSERT((index >= 0) && (index < Length()));
    return &raw_ptr()->data_[index];
  }

  HEAP_OBJECT_IMPLEMENTATION(FourByteString, String);
  friend class Class;
  friend class String;
};


class ExternalOneByteString : public String {
 public:
  virtual int32_t CharAt(intptr_t index) const {
    return *CharAddr(index);
  }

  virtual intptr_t CharSize() const {
    return kOneByteChar;
  }

  virtual bool IsExternal() const { return true; }
  virtual void* GetPeer() const {
    return raw_ptr()->external_data_->peer_;
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawExternalOneByteString));
  }

  static RawExternalOneByteString* New(const uint8_t* characters,
                                       intptr_t len,
                                       void* peer,
                                       PeerFinalizer callback,
                                       Heap::Space space);

 private:
  const uint8_t* CharAddr(intptr_t index) const {
    // TODO(iposva): Determine if we should throw an exception here.
    ASSERT((index >= 0) && (index < Length()));
    return &(raw_ptr()->external_data_->data_[index]);
  }

  void SetExternalData(ExternalStringData<uint8_t>* data) {
    raw_ptr()->external_data_ = data;
  }

  HEAP_OBJECT_IMPLEMENTATION(ExternalOneByteString, String);
  friend class Class;
  friend class String;
};


class ExternalTwoByteString : public String {
 public:
  virtual int32_t CharAt(intptr_t index) const {
    return *CharAddr(index);
  }

  virtual intptr_t CharSize() const {
    return kTwoByteChar;
  }

  virtual bool IsExternal() const { return true; }
  virtual void* GetPeer() const {
    return raw_ptr()->external_data_->peer_;
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawExternalTwoByteString));
  }

  static RawExternalTwoByteString* New(const uint16_t* characters,
                                       intptr_t len,
                                       void* peer,
                                       PeerFinalizer callback,
                                       Heap::Space space = Heap::kNew);

 private:
  const uint16_t* CharAddr(intptr_t index) const {
    // TODO(iposva): Determine if we should throw an exception here.
    ASSERT((index >= 0) && (index < Length()));
    return &(raw_ptr()->external_data_->data_[index]);
  }

  void SetExternalData(ExternalStringData<uint16_t>* data) {
    raw_ptr()->external_data_ = data;
  }

  HEAP_OBJECT_IMPLEMENTATION(ExternalTwoByteString, String);
  friend class Class;
  friend class String;
};


class ExternalFourByteString : public String {
 public:
  virtual int32_t CharAt(intptr_t index) const {
    return *CharAddr(index);
  }

  virtual intptr_t CharSize() const {
    return kFourByteChar;
  }

  virtual bool IsExternal() const { return true; }
  virtual void* GetPeer() const {
    return raw_ptr()->external_data_->peer_;
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawExternalFourByteString));
  }

  static RawExternalFourByteString* New(const uint32_t* characters,
                                        intptr_t len,
                                        void* peer,
                                        PeerFinalizer callback,
                                        Heap::Space space = Heap::kNew);

 private:
  const uint32_t* CharAddr(intptr_t index) const {
    // TODO(iposva): Determine if we should throw an exception here.
    ASSERT((index >= 0) && (index < Length()));
    return &(raw_ptr()->external_data_->data_[index]);
  }

  void SetExternalData(ExternalStringData<uint32_t>* data) {
    raw_ptr()->external_data_ = data;
  }

  HEAP_OBJECT_IMPLEMENTATION(ExternalFourByteString, String);
  friend class Class;
  friend class String;
};


class Bool : public Instance {
 public:
  bool value() const {
    return raw_ptr()->value_;
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawBool));
  }

  static RawBool* True();
  static RawBool* False();

  static RawBool* Get(bool value) {
    return value ? Bool::True() : Bool::False();
  }

 private:
  void set_value(bool value) const { raw_ptr()->value_ = value; }

  // New should only be called to initialize the two legal bool values.
  static RawBool* New(bool value);

  HEAP_OBJECT_IMPLEMENTATION(Bool, Instance);
  friend class Object;  // To initialize the true and false values.
  friend class Class;
};


class Array : public Instance {
 public:
  intptr_t Length() const {
    ASSERT(!IsNull());
    return Smi::Value(raw_ptr()->length_);
  }
  static intptr_t length_offset() { return OFFSET_OF(RawArray, length_); }
  static intptr_t data_offset() { return length_offset() + kWordSize; }

  RawObject* At(intptr_t index) const {
    return *ObjectAddr(index);
  }
  void SetAt(intptr_t index, const Object& value) const {
    // TODO(iposva): Add storing NoGCScope.
    StorePointer(ObjectAddr(index), value.raw());
  }

  virtual RawAbstractTypeArguments* GetTypeArguments() const {
    return raw_ptr()->type_arguments_;
  }
  virtual void SetTypeArguments(const AbstractTypeArguments& value) const {
    raw_ptr()->type_arguments_ = value.Canonicalize();
  }

  virtual bool Equals(const Instance& other) const;

  static intptr_t type_arguments_offset() {
    return OFFSET_OF(RawArray, type_arguments_);
  }

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawArray) == OFFSET_OF_RETURNED_VALUE(RawArray, data));
    return 0;
  }

  static intptr_t InstanceSize(intptr_t len) {
    // Ensure that variable length data is not adding to the object length.
    ASSERT(sizeof(RawArray) == (sizeof(RawObject) + (2 * kWordSize)));
    return RoundedAllocationSize(sizeof(RawArray) + (len * kWordSize));
  }

  // Make the array immutable to Dart code by switching the class pointer
  // to ImmutableArray.
  void MakeImmutable() const;

  static RawArray* New(intptr_t len, Heap::Space space = Heap::kNew);

  // Creates and returns a new array with 'new_length'. Copies all elements from
  // 'source' to the new array. 'new_length' must be greater than or equal to
  // 'source.Length()'. 'source' can be null.
  static RawArray* Grow(const Array& source,
                        int new_length,
                        Heap::Space space = Heap::kNew);

  // Returns the preallocated empty array, used to initialize array fields.
  static RawArray* Empty();

 protected:
  static RawArray* New(const Class& cls,
                       intptr_t len,
                       Heap::Space space = Heap::kNew);

 private:
  // Make sure that the array size cannot wrap around.
  static const intptr_t kMaxArrayElements = 512 * 1024 * 1024;

  RawObject** ObjectAddr(intptr_t index) const {
    // TODO(iposva): Determine if we should throw an exception here.
    ASSERT((index >= 0) && (index < Length()));
    return &raw_ptr()->data()[index];
  }

  void SetLength(intptr_t value) {
    // This is only safe because we create a new Smi, which does not cause
    // heap allocation.
    raw_ptr()->length_ = Smi::New(value);
  }

  HEAP_OBJECT_IMPLEMENTATION(Array, Instance);
  friend class Class;
};


class ImmutableArray : public Array {
 public:
  static RawImmutableArray* New(intptr_t len, Heap::Space space = Heap::kNew);

 private:
  HEAP_OBJECT_IMPLEMENTATION(ImmutableArray, Array);
  friend class Class;
};


class ByteArray : public Instance {
 public:
  virtual intptr_t Length() const;

  static void Copy(uint8_t* dst,
                   const ByteArray& src,
                   intptr_t src_offset,
                   intptr_t length);

  static void Copy(const ByteArray& dst,
                   intptr_t dst_offset,
                   const uint8_t* src,
                   intptr_t length);

  static void Copy(const ByteArray& dst,
                   intptr_t dst_offset,
                   const ByteArray& src,
                   intptr_t src_offset,
                   intptr_t length);

 private:
  virtual uint8_t* ByteAddr(intptr_t byte_offset) const;

  HEAP_OBJECT_IMPLEMENTATION(ByteArray, Instance);
  friend class Class;
};


class InternalByteArray : public ByteArray {
 public:
  intptr_t Length() const {
    ASSERT(!IsNull());
    return Smi::Value(raw_ptr()->length_);
  }

  static intptr_t length_offset() {
    return OFFSET_OF(RawInternalByteArray, length_);
  }

  static intptr_t data_offset() {
    return length_offset() + kWordSize;
  }

  template<typename T>
  T At(intptr_t byte_offset) const {
    T* addr = Addr<T>(byte_offset);
    ASSERT(Utils::IsAligned(reinterpret_cast<intptr_t>(addr), sizeof(T)));
    return *addr;
  }

  template<typename T>
  void SetAt(intptr_t byte_offset, T value) const {
    T* addr = Addr<T>(byte_offset);
    ASSERT(Utils::IsAligned(reinterpret_cast<intptr_t>(addr), sizeof(T)));
    *addr = value;
  }

  template<typename T>
  T UnalignedAt(intptr_t byte_offset) const {
    T result;
    memmove(&result, Addr<T>(byte_offset), sizeof(T));
    return result;
  }

  template<typename T>
  void SetUnalignedAt(intptr_t byte_offset, T value) const {
    memmove(Addr<T>(byte_offset), &value, sizeof(T));
  }

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawInternalByteArray) ==
           OFFSET_OF_RETURNED_VALUE(RawInternalByteArray, data));
    return 0;
  }

  static intptr_t InstanceSize(intptr_t len) {
    return RoundedAllocationSize(sizeof(RawInternalByteArray) + len);
  }

  static RawInternalByteArray* New(intptr_t len,
                                   Heap::Space space = Heap::kNew);
  static RawInternalByteArray* New(const uint8_t* data,
                                   intptr_t len,
                                   Heap::Space space = Heap::kNew);

 private:
  uint8_t* ByteAddr(intptr_t byte_offset) const {
    return Addr<uint8_t>(byte_offset);
  }

  template<typename T>
  T* Addr(intptr_t byte_offset) const {
    intptr_t limit = byte_offset + sizeof(T);
    // TODO(iposva): Determine if we should throw an exception here.
    ASSERT((byte_offset >= 0) && (limit <= Length()));
    uint8_t* addr = &raw_ptr()->data()[byte_offset];
    return reinterpret_cast<T*>(addr);
  }

  void SetLength(intptr_t value) {
    raw_ptr()->length_ = Smi::New(value);
  }

  HEAP_OBJECT_IMPLEMENTATION(InternalByteArray, ByteArray);
  friend class Class;
};


class ExternalByteArray : public ByteArray {
 public:
  intptr_t Length() const {
    ASSERT(!IsNull());
    return Smi::Value(raw_ptr()->length_);
  }

  template<typename T>
  T At(intptr_t byte_offset) const {
    T* addr = Addr<T>(byte_offset);
    ASSERT(Utils::IsAligned(reinterpret_cast<intptr_t>(addr), sizeof(T)));
    return *addr;
  }

  template<typename T>
  void SetAt(intptr_t byte_offset, T value) const {
    T* addr = Addr<T>(byte_offset);
    ASSERT(Utils::IsAligned(reinterpret_cast<intptr_t>(addr), sizeof(T)));
    *addr = value;
  }

  template<typename T>
  T UnalignedAt(intptr_t byte_offset) const {
    T result;
    memmove(&result, Addr<T>(byte_offset), sizeof(T));
    return result;
  }

  template<typename T>
  void SetUnalignedAt(intptr_t byte_offset, T value) const {
    memmove(Addr<T>(byte_offset), &value, sizeof(T));
  }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawExternalByteArray));
  }

  static RawExternalByteArray* New(uint8_t* data,
                                   intptr_t len,
                                   Heap::Space space = Heap::kNew);

 private:
  uint8_t* ByteAddr(intptr_t byte_offset) const {
    return Addr<uint8_t>(byte_offset);
  }

  template<typename T>
  T* Addr(intptr_t byte_offset) const {
    intptr_t limit = byte_offset + sizeof(T);
    // TODO(iposva): Determine if we should throw an exception here.
    ASSERT((byte_offset >= 0) && (limit <= Length()));
    uint8_t* addr = &raw_ptr()->data_[byte_offset];
    return reinterpret_cast<T*>(addr);
  }

  void SetLength(intptr_t value) {
    raw_ptr()->length_ = Smi::New(value);
  }

  void SetData(uint8_t* data) const {
    raw_ptr()->data_ = data;
  }

  HEAP_OBJECT_IMPLEMENTATION(ExternalByteArray, ByteArray);
  friend class Class;
};


class Closure : public Instance {
 public:
  RawFunction* function() const { return raw_ptr()->function_; }
  static intptr_t function_offset() {
    return OFFSET_OF(RawClosure, function_);
  }

  RawContext* context() const { return raw_ptr()->context_; }
  static intptr_t context_offset() { return OFFSET_OF(RawClosure, context_); }

  virtual RawAbstractTypeArguments* GetTypeArguments() const {
    return raw_ptr()->type_arguments_;
  }
  virtual void SetTypeArguments(const AbstractTypeArguments& value) const {
    raw_ptr()->type_arguments_ = value.Canonicalize();
  }
  static intptr_t type_arguments_offset() {
    return OFFSET_OF(RawClosure, type_arguments_);
  }

  // TODO(iposva): Remove smrck support once mapping to arbitrary is available.
  RawInteger* smrck() const { return raw_ptr()->smrck_; }
  void set_smrck(const Integer& smrck) const {
    StorePointer(&raw_ptr()->smrck_, smrck.raw());
  }
  static intptr_t smrck_offset() { return OFFSET_OF(RawClosure, smrck_); }

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawClosure));
  }

  static RawClosure* New(const Function& function,
                         const Context& context,
                         Heap::Space space = Heap::kNew);

 private:
  void set_function(const Function& value) const;
  void set_context(const Context& value) const;

  HEAP_OBJECT_IMPLEMENTATION(Closure, Instance);
  friend class Class;
};


// Internal stacktrace object used in exceptions for printing stack traces.
class Stacktrace : public Instance {
 public:
  intptr_t Length() const;
  RawFunction* FunctionAtFrame(intptr_t frame_index) const;
  RawCode* CodeAtFrame(intptr_t frame_index) const;
  RawSmi* PcOffsetAtFrame(intptr_t frame_index) const;
  void Append(const GrowableArray<uword>& stack_frame_pcs) const;

  static intptr_t InstanceSize() {
    return RoundedAllocationSize(sizeof(RawStacktrace));
  }
  static RawStacktrace* New(const GrowableArray<uword>& stack_frame_pcs,
                            Heap::Space space = Heap::kNew);

  const char* ToCStringInternal(bool verbose) const;

 private:
  void set_function_array(const Array& function_array) const;
  void set_code_array(const Array& code_array) const;
  void set_pc_offset_array(const Array& pc_offset_array) const;
  void SetupStacktrace(intptr_t index,
                       const GrowableArray<uword>& stack_frame_pcs) const;

  HEAP_OBJECT_IMPLEMENTATION(Stacktrace, Instance);
  friend class Class;
};


// Internal JavaScript regular expression object.
class JSRegExp : public Instance {
 public:
  // Meaning of RegExType:
  // kUninitialized: the type of th regexp has not been initialized yet.
  // kSimple: A simple pattern to match against, using string indexOf operation.
  // kComplex: A complex pattern to match.
  enum RegExType {
    kUnitialized = 0,
    kSimple,
    kComplex,
  };

  // Flags are passed to a regex object as follows:
  // 'i': ignore case, 'g': do global matches, 'm': pattern is multi line.
  enum Flags {
    kNone = 0,
    kGlobal = 1,
    kIgnoreCase = 2,
    kMultiLine = 4,
  };

  bool is_initialized() const { return (raw_ptr()->type_ != kUnitialized); }
  bool is_simple() const { return (raw_ptr()->type_ == kSimple); }
  bool is_complex() const { return (raw_ptr()->type_ == kComplex); }

  bool is_global() const { return (raw_ptr()->flags_ & kGlobal); }
  bool is_ignore_case() const { return (raw_ptr()->flags_ & kIgnoreCase); }
  bool is_multi_line() const { return (raw_ptr()->flags_ & kMultiLine); }

  RawString* pattern() const { return raw_ptr()->pattern_; }
  RawSmi* num_bracket_expressions() const {
    return raw_ptr()->num_bracket_expressions_;
  }

  void set_pattern(const String& pattern) const;
  void set_num_bracket_expressions(intptr_t value) const;
  void set_is_global() const { raw_ptr()->flags_ |= kGlobal; }
  void set_is_ignore_case() const { raw_ptr()->flags_ |= kIgnoreCase; }
  void set_is_multi_line() const { raw_ptr()->flags_ |= kMultiLine; }
  void set_is_simple() const { raw_ptr()->type_ = kSimple; }
  void set_is_complex() const { raw_ptr()->type_ = kComplex; }

  void* GetDataStartAddress() const;
  static RawJSRegExp* FromDataStartAddress(void* data);
  const char* Flags() const;

  virtual bool Equals(const Instance& other) const;

  static intptr_t InstanceSize() {
    ASSERT(sizeof(RawJSRegExp) == OFFSET_OF(RawJSRegExp, data_));
    return 0;
  }

  static intptr_t InstanceSize(intptr_t len) {
    return RoundedAllocationSize(sizeof(RawJSRegExp) + len);
  }

  static RawJSRegExp* New(intptr_t length, Heap::Space space = Heap::kNew);

 private:
  void set_type(RegExType type) const { raw_ptr()->type_ = type; }
  void set_flags(intptr_t value) const { raw_ptr()->flags_ = value; }

  void SetLength(intptr_t value) {
    // This is only safe because we create a new Smi, which does not cause
    // heap allocation.
    raw_ptr()->data_length_ = Smi::New(value);
  }

  HEAP_OBJECT_IMPLEMENTATION(JSRegExp, Instance);
  friend class Class;
};


// Breaking cycles and loops.
RawClass* Object::clazz() const {
  uword raw_value = reinterpret_cast<uword>(raw_);
  if ((raw_value & kSmiTagMask) == kSmiTag) {
    return Smi::Class();
  }
  return raw_->ptr()->class_;
}


void Object::SetRaw(RawObject* value) {
  // NOTE: The assignment "raw_ = value" should be the first statement in
  // this function. Also do not use 'value' in this function after the
  // assignment (use 'raw_' instead).
  raw_ = value;
  if ((reinterpret_cast<uword>(raw_) & kSmiTagMask) == kSmiTag) {
    set_vtable(Smi::handle_vtable_);
    return;
  }
#ifdef DEBUG
  Heap* isolate_heap = Isolate::Current()->heap();
  Heap* vm_isolate_heap = Dart::vm_isolate()->heap();
  ASSERT(isolate_heap->Contains(reinterpret_cast<uword>(raw_->ptr())) ||
         vm_isolate_heap->Contains(reinterpret_cast<uword>(raw_->ptr())));
#endif
  set_vtable((raw_ == null_) ?
             handle_vtable_ : raw_->ptr()->class_->ptr()->handle_vtable_);
}


bool Function::HasCode() const {
  return code() != Code::null();
}


intptr_t Field::Offset() const {
  ASSERT(!is_static());  // Offset is valid only for instance fields.
  return Smi::Value(reinterpret_cast<RawSmi*>(raw_ptr()->value_));
}


void Field::SetOffset(intptr_t value) const {
  ASSERT(!is_static());  // SetOffset is valid only for instance fields.
  raw_ptr()->value_ = Smi::New(value);
}


intptr_t TokenStream::Length() const {
  return Smi::Value(raw_ptr()->length_);
}


Token::Kind TokenStream::KindAt(intptr_t index) const {
  return static_cast<Token::Kind>(
      Smi::Value(*SmiAddr(index, RawTokenStream::kKindEntry)));
}


void Context::SetAt(intptr_t index, const Instance& value) const {
  StorePointer(InstanceAddr(index), value.raw());
}

}  // namespace dart

#endif  // VM_OBJECT_H_