Source/JavaScriptCore/runtime/JSCell.h - WebKit - Git at Google

 /*
  *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
  *  Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Library General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  *  Library General Public License for more details.
  *
  *  You should have received a copy of the GNU Library General Public License
  *  along with this library; see the file COPYING.LIB.  If not, write to
  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  *  Boston, MA 02110-1301, USA.
  *
  */

 #ifndef JSCell_h
 #define JSCell_h

 #include "CallData.h"
 #include "ConstructData.h"
 #include "EnumerationMode.h"
 #include "Heap.h"
 #include "IndexingType.h"
 #include "JSLock.h"
 #include "JSTypeInfo.h"
 #include "SlotVisitor.h"
 #include "TypedArrayType.h"
 #include "WriteBarrier.h"
 #include <wtf/Noncopyable.h>

 namespace JSC {

 class CopyVisitor;
 class ExecState;
 class Identifier;
 class JSArrayBufferView;
 class JSDestructibleObject;
 class JSGlobalObject;
 class LLIntOffsetsExtractor;
 class PropertyDescriptor;
 class PropertyNameArray;
 class Structure;

 template<typename T> void* allocateCell(Heap&);
 template<typename T> void* allocateCell(Heap&, size_t);

 #define DECLARE_EXPORT_INFO                                             \
     protected:                                                          \
         static JS_EXPORTDATA const ::JSC::ClassInfo s_info;             \
     public:                                                             \
         static const ::JSC::ClassInfo* info() { return &s_info; }

 #define DECLARE_INFO                                                    \
     protected:                                                          \
         static const ::JSC::ClassInfo s_info;                           \
     public:                                                             \
         static const ::JSC::ClassInfo* info() { return &s_info; }

 class JSCell {
     friend class JSValue;
     friend class MarkedBlock;
     template<typename T> friend void* allocateCell(Heap&);
     template<typename T> friend void* allocateCell(Heap&, size_t);

 public:
     static const unsigned StructureFlags = 0;

     static const bool needsDestruction = false;

     static JSCell* seenMultipleCalleeObjects() { return bitwise_cast<JSCell*>(static_cast<uintptr_t>(1)); }

     enum CreatingEarlyCellTag { CreatingEarlyCell };
     JSCell(CreatingEarlyCellTag);

 protected:
     JSCell(VM&, Structure*);
     JS_EXPORT_PRIVATE static void destroy(JSCell*);

 public:
     // Querying the type.
     bool isString() const;
     bool isSymbol() const;
     bool isObject() const;
     bool isGetterSetter() const;
     bool isCustomGetterSetter() const;
     bool isProxy() const;
     bool inherits(const ClassInfo*) const;
     bool isAPIValueWrapper() const;

     JSType type() const;
     IndexingType indexingType() const;
     StructureID structureID() const { return m_structureID; }
     Structure* structure() const;
     Structure* structure(VM&) const;
     void setStructure(VM&, Structure*);
     void clearStructure() { m_structureID = 0; }

     TypeInfo::InlineTypeFlags inlineTypeFlags() const { return m_flags; }

     const char* className() const;

     VM* vm() const;

     // Extracting the value.
     JS_EXPORT_PRIVATE bool getString(ExecState*, String&) const;
     JS_EXPORT_PRIVATE String getString(ExecState*) const; // null string if not a string
     JS_EXPORT_PRIVATE JSObject* getObject(); // NULL if not an object
     const JSObject* getObject() const; // NULL if not an object

     // Returns information about how to call/construct this cell as a function/constructor. May tell
     // you that the cell is not callable or constructor (default is that it's not either). If it
     // says that the function is callable, and the TypeOfShouldCallGetCallData type flag is set, and
     // this is an object, then typeof will return "function" instead of "object". These methods
     // cannot change their minds and must be thread-safe. They are sometimes called from compiler
     // threads.
     JS_EXPORT_PRIVATE static CallType getCallData(JSCell*, CallData&);
     JS_EXPORT_PRIVATE static ConstructType getConstructData(JSCell*, ConstructData&);

     // Basic conversions.
     JS_EXPORT_PRIVATE JSValue toPrimitive(ExecState*, PreferredPrimitiveType) const;
     bool getPrimitiveNumber(ExecState*, double& number, JSValue&) const;
     bool toBoolean(ExecState*) const;
     TriState pureToBoolean() const;
     JS_EXPORT_PRIVATE double toNumber(ExecState*) const;
     JS_EXPORT_PRIVATE JSObject* toObject(ExecState*, JSGlobalObject*) const;

     void dump(PrintStream&) const;
     JS_EXPORT_PRIVATE static void dumpToStream(const JSCell*, PrintStream&);
     static void visitChildren(JSCell*, SlotVisitor&);
     JS_EXPORT_PRIVATE static void copyBackingStore(JSCell*, CopyVisitor&, CopyToken);

     // Object operations, with the toObject operation included.
     const ClassInfo* classInfo() const;
     const MethodTable* methodTable() const;
     const MethodTable* methodTable(VM&) const;
     static void put(JSCell*, ExecState*, PropertyName, JSValue, PutPropertySlot&);
     static void putByIndex(JSCell*, ExecState*, unsigned propertyName, JSValue, bool shouldThrow);

     static bool deleteProperty(JSCell*, ExecState*, PropertyName);
     static bool deletePropertyByIndex(JSCell*, ExecState*, unsigned propertyName);

     static JSValue toThis(JSCell*, ExecState*, ECMAMode);

     void zap() { *reinterpret_cast<uintptr_t**>(this) = 0; }
     bool isZapped() const { return !*reinterpret_cast<uintptr_t* const*>(this); }

     static bool canUseFastGetOwnProperty(const Structure&);
     JSValue fastGetOwnProperty(VM&, Structure&, PropertyName);

     enum GCData : uint8_t {
         Marked = 0, // The object has survived a GC and is in the old gen.
         NotMarked = 1, // The object is new and in the eden gen.
         MarkedAndRemembered = 2, // The object is in the GC's remembered set.

         // The object being in the GC's remembered set implies that it is also
         // Marked. This is because objects are only added to the remembered sets
         // by write barriers, and write barriers are only interested in old gen
         // objects that point to potential eden gen objects.
     };

     void setMarked() { m_gcData = Marked; }
     void setRemembered(bool remembered)
     {
         ASSERT(m_gcData == (remembered ? Marked : MarkedAndRemembered));
         m_gcData = remembered ? MarkedAndRemembered : Marked;
     }
     bool isMarked() const
     {
         switch (m_gcData) {
         case Marked:
         case MarkedAndRemembered:
             return true;
         case NotMarked:
             return false;
         }
         RELEASE_ASSERT_NOT_REACHED();
         return false;
     }
     bool isRemembered() const { return m_gcData == MarkedAndRemembered; }

     static ptrdiff_t structureIDOffset()
     {
         return OBJECT_OFFSETOF(JSCell, m_structureID);
     }

     static ptrdiff_t typeInfoFlagsOffset()
     {
         return OBJECT_OFFSETOF(JSCell, m_flags);
     }

     static ptrdiff_t typeInfoTypeOffset()
     {
         return OBJECT_OFFSETOF(JSCell, m_type);
     }

     static ptrdiff_t indexingTypeOffset()
     {
         return OBJECT_OFFSETOF(JSCell, m_indexingType);
     }

     static ptrdiff_t gcDataOffset()
     {
         return OBJECT_OFFSETOF(JSCell, m_gcData);
     }

     static const TypedArrayType TypedArrayStorageType = NotTypedArray;
 protected:

     void finishCreation(VM&);
     void finishCreation(VM&, Structure*, CreatingEarlyCellTag);

     // Dummy implementations of override-able static functions for classes to put in their MethodTable
     static JSValue defaultValue(const JSObject*, ExecState*, PreferredPrimitiveType);
     static NO_RETURN_DUE_TO_CRASH void getOwnPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
     static NO_RETURN_DUE_TO_CRASH void getOwnNonIndexPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
     static NO_RETURN_DUE_TO_CRASH void getPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);

     static uint32_t getEnumerableLength(ExecState*, JSObject*);
     static NO_RETURN_DUE_TO_CRASH void getStructurePropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);
     static NO_RETURN_DUE_TO_CRASH void getGenericPropertyNames(JSObject*, ExecState*, PropertyNameArray&, EnumerationMode);

     static String className(const JSObject*);
     JS_EXPORT_PRIVATE static bool customHasInstance(JSObject*, ExecState*, JSValue);
     static bool defineOwnProperty(JSObject*, ExecState*, PropertyName, const PropertyDescriptor&, bool shouldThrow);
     static bool getOwnPropertySlot(JSObject*, ExecState*, PropertyName, PropertySlot&);
     static bool getOwnPropertySlotByIndex(JSObject*, ExecState*, unsigned propertyName, PropertySlot&);
     JS_EXPORT_PRIVATE static ArrayBuffer* slowDownAndWasteMemory(JSArrayBufferView*);
     JS_EXPORT_PRIVATE static PassRefPtr<ArrayBufferView> getTypedArrayImpl(JSArrayBufferView*);

 private:
     friend class LLIntOffsetsExtractor;

     StructureID m_structureID;
     IndexingType m_indexingType;
     JSType m_type;
     TypeInfo::InlineTypeFlags m_flags;
     uint8_t m_gcData;
 };

 template<typename To, typename From>
 inline To& jsCast(From& from)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(from.JSCell::inherits(std::remove_reference<To>::type::info()));
     return static_cast<To&>(from);
 }

 template<typename To, typename From>
 inline To jsCast(From* from)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!from || from->JSCell::inherits(std::remove_pointer<To>::type::info()));
     return static_cast<To>(from);
 }

 template<typename To>
 inline To jsCast(JSValue from)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(from.isCell() && from.asCell()->JSCell::inherits(std::remove_pointer<To>::type::info()));
     return static_cast<To>(from.asCell());
 }

 template<typename To, typename From>
 inline To jsDynamicCast(From* from)
 {
     if (LIKELY(from->inherits(std::remove_pointer<To>::type::info())))
         return static_cast<To>(from);
     return nullptr;
 }

 template<typename To>
 inline To jsDynamicCast(JSValue from)
 {
     if (LIKELY(from.isCell() && from.asCell()->inherits(std::remove_pointer<To>::type::info())))
         return static_cast<To>(from.asCell());
     return nullptr;
 }

 } // namespace JSC

 #endif // JSCell_h
	/*
	* Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
	* Copyright (C) 2001 Peter Kelly (pmk@post.com)
	* Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009 Apple Inc. All rights reserved.
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Library General Public
	* License as published by the Free Software Foundation; either
	* version 2 of the License, or (at your option) any later version.
	*
	* This library is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Library General Public License for more details.
	*
	* You should have received a copy of the GNU Library General Public License
	* along with this library; see the file COPYING.LIB. If not, write to
	* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
	* Boston, MA 02110-1301, USA.
	*
	*/

	#ifndef JSCell_h
	#define JSCell_h

	#include "CallData.h"
	#include "ConstructData.h"
	#include "EnumerationMode.h"
	#include "Heap.h"
	#include "IndexingType.h"
	#include "JSLock.h"
	#include "JSTypeInfo.h"
	#include "SlotVisitor.h"
	#include "TypedArrayType.h"
	#include "WriteBarrier.h"
	#include <wtf/Noncopyable.h>

	namespace JSC {

	class CopyVisitor;
	class ExecState;
	class Identifier;
	class JSArrayBufferView;
	class JSDestructibleObject;
	class JSGlobalObject;
	class LLIntOffsetsExtractor;
	class PropertyDescriptor;
	class PropertyNameArray;
	class Structure;

	template<typename T> void* allocateCell(Heap&);
	template<typename T> void* allocateCell(Heap&, size_t);

	#define DECLARE_EXPORT_INFO \
	protected: \
	static JS_EXPORTDATA const ::JSC::ClassInfo s_info; \
	public: \
	static const ::JSC::ClassInfo* info() { return &s_info; }

	#define DECLARE_INFO \
	protected: \
	static const ::JSC::ClassInfo s_info; \
	public: \
	static const ::JSC::ClassInfo* info() { return &s_info; }

	class JSCell {
	friend class JSValue;
	friend class MarkedBlock;
	template<typename T> friend void* allocateCell(Heap&);
	template<typename T> friend void* allocateCell(Heap&, size_t);

	public:
	static const unsigned StructureFlags = 0;

	static const bool needsDestruction = false;

	static JSCell* seenMultipleCalleeObjects() { return bitwise_cast<JSCell*>(static_cast<uintptr_t>(1)); }

	enum CreatingEarlyCellTag { CreatingEarlyCell };
	JSCell(CreatingEarlyCellTag);

	protected:
	JSCell(VM&, Structure*);
	JS_EXPORT_PRIVATE static void destroy(JSCell*);

	public:
	// Querying the type.
	bool isString() const;
	bool isSymbol() const;
	bool isObject() const;
	bool isGetterSetter() const;
	bool isCustomGetterSetter() const;
	bool isProxy() const;
	bool inherits(const ClassInfo*) const;
	bool isAPIValueWrapper() const;

	JSType type() const;
	IndexingType indexingType() const;
	StructureID structureID() const { return m_structureID; }
	Structure* structure() const;
	Structure* structure(VM&) const;
	void setStructure(VM&, Structure*);
	void clearStructure() { m_structureID = 0; }

	TypeInfo::InlineTypeFlags inlineTypeFlags() const { return m_flags; }

	const char* className() const;

	VM* vm() const;

	// Extracting the value.
	JS_EXPORT_PRIVATE bool getString(ExecState*, String&) const;
	JS_EXPORT_PRIVATE String getString(ExecState*) const; // null string if not a string
	JS_EXPORT_PRIVATE JSObject* getObject(); // NULL if not an object
	const JSObject* getObject() const; // NULL if not an object

	// Returns information about how to call/construct this cell as a function/constructor. May tell
	// you that the cell is not callable or constructor (default is that it's not either). If it
	// says that the function is callable, and the TypeOfShouldCallGetCallData type flag is set, and
	// this is an object, then typeof will return "function" instead of "object". These methods
	// cannot change their minds and must be thread-safe. They are sometimes called from compiler
	// threads.
	JS_EXPORT_PRIVATE static CallType getCallData(JSCell*, CallData&);
	JS_EXPORT_PRIVATE static ConstructType getConstructData(JSCell*, ConstructData&);

	// Basic conversions.
	JS_EXPORT_PRIVATE JSValue toPrimitive(ExecState*, PreferredPrimitiveType) const;
	bool getPrimitiveNumber(ExecState*, double& number, JSValue&) const;
	bool toBoolean(ExecState*) const;
	TriState pureToBoolean() const;
	JS_EXPORT_PRIVATE double toNumber(ExecState*) const;
	JS_EXPORT_PRIVATE JSObject* toObject(ExecState, JSGlobalObject) const;

	void dump(PrintStream&) const;
	JS_EXPORT_PRIVATE static void dumpToStream(const JSCell*, PrintStream&);
	static void visitChildren(JSCell*, SlotVisitor&);
	JS_EXPORT_PRIVATE static void copyBackingStore(JSCell*, CopyVisitor&, CopyToken);

	// Object operations, with the toObject operation included.
	const ClassInfo* classInfo() const;
	const MethodTable* methodTable() const;
	const MethodTable* methodTable(VM&) const;
	static void put(JSCell, ExecState, PropertyName, JSValue, PutPropertySlot&);
	static void putByIndex(JSCell, ExecState, unsigned propertyName, JSValue, bool shouldThrow);

	static bool deleteProperty(JSCell, ExecState, PropertyName);
	static bool deletePropertyByIndex(JSCell, ExecState, unsigned propertyName);

	static JSValue toThis(JSCell, ExecState, ECMAMode);

	void zap() { reinterpret_cast<uintptr_t*>(this) = 0; }
	bool isZapped() const { return !reinterpret_cast<uintptr_t const*>(this); }

	static bool canUseFastGetOwnProperty(const Structure&);
	JSValue fastGetOwnProperty(VM&, Structure&, PropertyName);

	enum GCData : uint8_t {
	Marked = 0, // The object has survived a GC and is in the old gen.
	NotMarked = 1, // The object is new and in the eden gen.
	MarkedAndRemembered = 2, // The object is in the GC's remembered set.

	// The object being in the GC's remembered set implies that it is also
	// Marked. This is because objects are only added to the remembered sets
	// by write barriers, and write barriers are only interested in old gen
	// objects that point to potential eden gen objects.
	};

	void setMarked() { m_gcData = Marked; }
	void setRemembered(bool remembered)
	{
	ASSERT(m_gcData == (remembered ? Marked : MarkedAndRemembered));
	m_gcData = remembered ? MarkedAndRemembered : Marked;
	}
	bool isMarked() const
	{
	switch (m_gcData) {
	case Marked:
	case MarkedAndRemembered:
	return true;
	case NotMarked:
	return false;
	}
	RELEASE_ASSERT_NOT_REACHED();
	return false;
	}
	bool isRemembered() const { return m_gcData == MarkedAndRemembered; }

	static ptrdiff_t structureIDOffset()
	{
	return OBJECT_OFFSETOF(JSCell, m_structureID);
	}

	static ptrdiff_t typeInfoFlagsOffset()
	{
	return OBJECT_OFFSETOF(JSCell, m_flags);
	}

	static ptrdiff_t typeInfoTypeOffset()
	{
	return OBJECT_OFFSETOF(JSCell, m_type);
	}

	static ptrdiff_t indexingTypeOffset()
	{
	return OBJECT_OFFSETOF(JSCell, m_indexingType);
	}

	static ptrdiff_t gcDataOffset()
	{
	return OBJECT_OFFSETOF(JSCell, m_gcData);
	}

	static const TypedArrayType TypedArrayStorageType = NotTypedArray;
	protected:

	void finishCreation(VM&);
	void finishCreation(VM&, Structure*, CreatingEarlyCellTag);

	// Dummy implementations of override-able static functions for classes to put in their MethodTable
	static JSValue defaultValue(const JSObject, ExecState, PreferredPrimitiveType);
	static NO_RETURN_DUE_TO_CRASH void getOwnPropertyNames(JSObject, ExecState, PropertyNameArray&, EnumerationMode);
	static NO_RETURN_DUE_TO_CRASH void getOwnNonIndexPropertyNames(JSObject, ExecState, PropertyNameArray&, EnumerationMode);
	static NO_RETURN_DUE_TO_CRASH void getPropertyNames(JSObject, ExecState, PropertyNameArray&, EnumerationMode);

	static uint32_t getEnumerableLength(ExecState, JSObject);
	static NO_RETURN_DUE_TO_CRASH void getStructurePropertyNames(JSObject, ExecState, PropertyNameArray&, EnumerationMode);
	static NO_RETURN_DUE_TO_CRASH void getGenericPropertyNames(JSObject, ExecState, PropertyNameArray&, EnumerationMode);

	static String className(const JSObject*);
	JS_EXPORT_PRIVATE static bool customHasInstance(JSObject, ExecState, JSValue);
	static bool defineOwnProperty(JSObject, ExecState, PropertyName, const PropertyDescriptor&, bool shouldThrow);
	static bool getOwnPropertySlot(JSObject, ExecState, PropertyName, PropertySlot&);
	static bool getOwnPropertySlotByIndex(JSObject, ExecState, unsigned propertyName, PropertySlot&);
	JS_EXPORT_PRIVATE static ArrayBuffer* slowDownAndWasteMemory(JSArrayBufferView*);
	JS_EXPORT_PRIVATE static PassRefPtr<ArrayBufferView> getTypedArrayImpl(JSArrayBufferView*);

	private:
	friend class LLIntOffsetsExtractor;

	StructureID m_structureID;
	IndexingType m_indexingType;
	JSType m_type;
	TypeInfo::InlineTypeFlags m_flags;
	uint8_t m_gcData;
	};

	template<typename To, typename From>
	inline To& jsCast(From& from)
	{
	ASSERT_WITH_SECURITY_IMPLICATION(from.JSCell::inherits(std::remove_reference<To>::type::info()));
	return static_cast<To&>(from);
	}

	template<typename To, typename From>
	inline To jsCast(From* from)
	{
	ASSERT_WITH_SECURITY_IMPLICATION(!from \|\| from->JSCell::inherits(std::remove_pointer<To>::type::info()));
	return static_cast<To>(from);
	}

	template<typename To>
	inline To jsCast(JSValue from)
	{
	ASSERT_WITH_SECURITY_IMPLICATION(from.isCell() && from.asCell()->JSCell::inherits(std::remove_pointer<To>::type::info()));
	return static_cast<To>(from.asCell());
	}

	template<typename To, typename From>
	inline To jsDynamicCast(From* from)
	{
	if (LIKELY(from->inherits(std::remove_pointer<To>::type::info())))
	return static_cast<To>(from);
	return nullptr;
	}

	template<typename To>
	inline To jsDynamicCast(JSValue from)
	{
	if (LIKELY(from.isCell() && from.asCell()->inherits(std::remove_pointer<To>::type::info())))
	return static_cast<To>(from.asCell());
	return nullptr;
	}

	} // namespace JSC

	#endif // JSCell_h