gecko-dev/xpcom/ds/nsAtomTable.h

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#ifndef nsAtomTable_h__
#define nsAtomTable_h__

#include "nsIAtom.h"

/**
 * A threadsafely-refcounted implementation of nsIAtom.  Note that
 * AtomImpl objects are sometimes converted into PermanentAtomImpl
 * objects using placement new and just overwriting the vtable pointer.
 */

class AtomImpl : public nsIAtom {
public:
  AtomImpl();

protected:
  // We don't need a virtual destructor here because PermanentAtomImpl
  // deletions aren't handled through Release().
  ~AtomImpl();

public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSIATOM

  enum { REFCNT_PERMANENT_SENTINEL = PR_UINT32_MAX };

  virtual PRBool IsPermanent();

  // We can't use the virtual function in the base class destructor.
  PRBool IsPermanentInDestructor() {
    return mRefCnt == REFCNT_PERMANENT_SENTINEL;
  }

  void* operator new(size_t size, const nsACString& aString) CPP_THROW_NEW;

  void operator delete(void* ptr) {
    ::operator delete(ptr);
  }

  // for |#ifdef NS_BUILD_REFCNT_LOGGING| access to reference count
  nsrefcnt GetRefCount() { return mRefCnt; }

  // Actually more; 0 terminated. This slot is reserved for the
  // terminating zero.
  char mString[1];
};

/**
 * A non-refcounted implementation of nsIAtom.
 */

class PermanentAtomImpl : public AtomImpl {
public:
  PermanentAtomImpl();
  ~PermanentAtomImpl();
  NS_IMETHOD_(nsrefcnt) AddRef();
  NS_IMETHOD_(nsrefcnt) Release();

  virtual PRBool IsPermanent();

  void* operator new(size_t size, const nsACString& aString) CPP_THROW_NEW {
    return AtomImpl::operator new(size, aString);
  }
  void* operator new(size_t size, AtomImpl* aAtom) CPP_THROW_NEW;

};

void NS_PurgeAtomTable();

#endif // nsAtomTable_h__