text: // Copyright 2015 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_SCAVENGER_H_
  #define V8_HEAP_SCAVENGER_H_
  
  #include "src/heap/objects-visiting.h"
  
  namespace v8 {
  namespace internal {
  
  typedef void (*ScavengingCallback)(Map* map, HeapObject** slot,
                                     HeapObject* object);
  
  class Scavenger {
   public:
    explicit Scavenger(Heap* heap) : heap_(heap) {}
  
    // Initializes static visitor dispatch tables.
    static void Initialize();
  
    // Callback function passed to Heap::Iterate etc.  Copies an object if
    // necessary, the object might be promoted to an old space.  The caller must
    // ensure the precondition that the object is (a) a heap object and (b) in
    // the heap's from space.
    static inline void ScavengeObject(HeapObject** p, HeapObject* object);
  
    // Slow part of {ScavengeObject} above.
    static void ScavengeObjectSlow(HeapObject** p, HeapObject* object);
  
    // Chooses an appropriate static visitor table depending on the current state
    // of the heap (i.e. incremental marking, logging and profiling).
    void SelectScavengingVisitorsTable();
  
    Isolate* isolate();
    Heap* heap() { return heap_; }
  
   private:
    Heap* heap_;
    VisitorDispatchTable<ScavengingCallback> scavenging_visitors_table_;
  };
  
  
  // Helper class for turning the scavenger into an object visitor that is also
  // filtering out non-HeapObjects and objects which do not reside in new space.
  class ScavengeVisitor : public ObjectVisitor {
   public:
    explicit ScavengeVisitor(Heap* heap) : heap_(heap) {}
  
    void VisitPointer(Object** p);
    void VisitPointers(Object** start, Object** end);
  
   private:
    inline void ScavengePointer(Object** p);
  
    Heap* heap_;
  };
  
  
  // Helper class for turning the scavenger into an object visitor that is also
  // filtering out non-HeapObjects and objects which do not reside in new space.
  class StaticScavengeVisitor
      : public StaticNewSpaceVisitor<StaticScavengeVisitor> {
   public:
    static inline void VisitPointer(Heap* heap, Object** p);
  };
  
  }  // namespace internal
  }  // namespace v8
  
  #endif  // V8_HEAP_SCAVENGER_H_
  