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// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_HEAP_OBJECTS_VISITING_H_
#define V8_HEAP_OBJECTS_VISITING_H_
#include "src/allocation.h"
#include "src/layout-descriptor.h"
#include "src/objects-body-descriptors.h"
#include "src/objects.h"
#include "src/objects/hash-table.h"
#include "src/objects/ordered-hash-table.h"
#include "src/objects/string.h"
#include "src/visitors.h"
namespace v8 {
namespace internal {
class BigInt;
class BytecodeArray;
class DataHandler;
class JSArrayBuffer;
class JSRegExp;
class JSWeakCollection;
class UncompiledDataWithoutPreParsedScope;
class UncompiledDataWithPreParsedScope;
#define TYPED_VISITOR_ID_LIST(V) \
V(AllocationSite) \
V(BigInt) \
V(ByteArray) \
V(BytecodeArray) \
V(Cell) \
V(Code) \
V(CodeDataContainer) \
V(ConsString) \
V(DataHandler) \
V(EphemeronHashTable) \
V(FeedbackCell) \
V(FeedbackVector) \
V(FixedArray) \
V(FixedDoubleArray) \
V(FixedFloat64Array) \
V(FixedTypedArrayBase) \
V(JSArrayBuffer) \
V(JSFunction) \
V(JSObject) \
V(JSWeakCollection) \
V(Map) \
V(Oddball) \
V(PreParsedScopeData) \
V(PropertyArray) \
V(PropertyCell) \
V(PrototypeInfo) \
V(SeqOneByteString) \
V(SeqTwoByteString) \
V(SharedFunctionInfo) \
V(SlicedString) \
V(SmallOrderedHashMap) \
V(SmallOrderedHashSet) \
V(Symbol) \
V(ThinString) \
V(TransitionArray) \
V(UncompiledDataWithoutPreParsedScope) \
V(UncompiledDataWithPreParsedScope) \
V(WasmInstanceObject) \
V(WeakCell)
// The base class for visitors that need to dispatch on object type. The default
// behavior of all visit functions is to iterate body of the given object using
// the BodyDescriptor of the object.
//
// The visit functions return the size of the object cast to ResultType.
//
// This class is intended to be used in the following way:
//
// class SomeVisitor : public HeapVisitor<ResultType, SomeVisitor> {
// ...
// }
template <typename ResultType, typename ConcreteVisitor>
class HeapVisitor : public ObjectVisitor {
public:
V8_INLINE ResultType Visit(HeapObject* object);
V8_INLINE ResultType Visit(Map* map, HeapObject* object);
protected:
// A guard predicate for visiting the object.
// If it returns false then the default implementations of the Visit*
// functions bailout from iterating the object pointers.
V8_INLINE bool ShouldVisit(HeapObject* object) { return true; }
// Guard predicate for visiting the objects map pointer separately.
V8_INLINE bool ShouldVisitMapPointer() { return true; }
// A callback for visiting the map pointer in the object header.
V8_INLINE void VisitMapPointer(HeapObject* host, HeapObject** map);
// If this predicate returns false, then the heap visitor will fail
// in default Visit implemention for subclasses of JSObject.
V8_INLINE bool AllowDefaultJSObjectVisit() { return true; }
#define VISIT(type) V8_INLINE ResultType Visit##type(Map* map, type* object);
TYPED_VISITOR_ID_LIST(VISIT)
#undef VISIT
V8_INLINE ResultType VisitShortcutCandidate(Map* map, ConsString* object);
V8_INLINE ResultType VisitNativeContext(Map* map, Context* object);
V8_INLINE ResultType VisitDataObject(Map* map, HeapObject* object);
V8_INLINE ResultType VisitJSObjectFast(Map* map, JSObject* object);
V8_INLINE ResultType VisitJSApiObject(Map* map, JSObject* object);
V8_INLINE ResultType VisitStruct(Map* map, HeapObject* object);
V8_INLINE ResultType VisitFreeSpace(Map* map, FreeSpace* object);
V8_INLINE ResultType VisitWeakArray(Map* map, HeapObject* object);
template <typename T>
static V8_INLINE T* Cast(HeapObject* object);
};
template <typename ConcreteVisitor>
class NewSpaceVisitor : public HeapVisitor<int, ConcreteVisitor> {
public:
V8_INLINE bool ShouldVisitMapPointer() { return false; }
// Special cases for young generation.
V8_INLINE int VisitJSFunction(Map* map, JSFunction* object);
V8_INLINE int VisitNativeContext(Map* map, Context* object);
V8_INLINE int VisitJSApiObject(Map* map, JSObject* object);
int VisitBytecodeArray(Map* map, BytecodeArray* object) {
UNREACHABLE();
return 0;
}
int VisitSharedFunctionInfo(Map* map, SharedFunctionInfo* object) {
UNREACHABLE();
return 0;
}
};
class WeakObjectRetainer;
// A weak list is single linked list where each element has a weak pointer to
// the next element. Given the head of the list, this function removes dead
// elements from the list and if requested records slots for next-element
// pointers. The template parameter T is a WeakListVisitor that defines how to
// access the next-element pointers.
template <class T>
Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer);
} // namespace internal
} // namespace v8
#endif // V8_HEAP_OBJECTS_VISITING_H_