pjs/xpcom/base/nsCycleCollectionParticipant.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
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 * the Initial Developer. All Rights Reserved.
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 *
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#ifndef nsCycleCollectionParticipant_h__
#define nsCycleCollectionParticipant_h__

#include "nsISupports.h"

#define NS_CYCLECOLLECTIONPARTICIPANT_IID                                      \
{                                                                              \
    0x8057ad9e,                                                                \
    0x3ecc,                                                                    \
    0x4e89,                                                                    \
    { 0x89, 0xac, 0x0a, 0x71, 0xf3, 0x8b, 0x14, 0xc2 }                         \
}

/**
 * Special IID to get at the base nsISupports for a class. Usually this is the
 * canonical nsISupports pointer, but in the case of tearoffs for example it is
 * the base nsISupports pointer of the tearoff. This allow the cycle collector
 * to have separate nsCycleCollectionParticipant's for tearoffs or aggregated
 * classes.
 */
#define NS_CYCLECOLLECTIONISUPPORTS_IID                                        \
{                                                                              \
    0xc61eac14,                                                                \
    0x5f7a,                                                                    \
    0x4481,                                                                    \
    { 0x96, 0x5e, 0x7e, 0xaa, 0x6e, 0xff, 0xa8, 0x5f }                         \
}

/**
 * Just holds the IID so NS_GET_IID works.
 */
class NS_COM nsCycleCollectionISupports
{
public:
    NS_DECLARE_STATIC_IID_ACCESSOR(NS_CYCLECOLLECTIONISUPPORTS_IID)
};

NS_DEFINE_STATIC_IID_ACCESSOR(nsCycleCollectionISupports, 
                              NS_CYCLECOLLECTIONISUPPORTS_IID)

#undef  IMETHOD_VISIBILITY
#define IMETHOD_VISIBILITY NS_VISIBILITY_DEFAULT

struct nsCycleCollectionTraversalCallback
{
    // You must call DescribeNode() with an accurate refcount,
    // otherwise cycle collection will fail, and probably crash.
    // Providing an accurate objsz or objname is optional.
    virtual void DescribeNode(size_t refcount, 
                              size_t objsz, 
                              const char *objname) = 0;
    virtual void NoteScriptChild(PRUint32 langID, void *child) = 0;
    virtual void NoteXPCOMChild(nsISupports *child) = 0;
};

class NS_COM nsCycleCollectionParticipant
    : public nsISupports
{
public:
    NS_DECLARE_STATIC_IID_ACCESSOR(NS_CYCLECOLLECTIONPARTICIPANT_IID)
    NS_DECL_ISUPPORTS

    NS_IMETHOD Unlink(nsISupports *p);
    NS_IMETHOD Traverse(nsISupports *p, 
                        nsCycleCollectionTraversalCallback &cb);
    NS_IMETHOD_(void) UnmarkPurple(nsISupports *p);

#ifdef DEBUG
    NS_EXTERNAL_VIS_(PRBool) CheckForRightISupports(nsISupports *s);
#endif
};

NS_DEFINE_STATIC_IID_ACCESSOR(nsCycleCollectionParticipant, 
                              NS_CYCLECOLLECTIONPARTICIPANT_IID)

#undef  IMETHOD_VISIBILITY
#define IMETHOD_VISIBILITY NS_VISIBILITY_HIDDEN


///////////////////////////////////////////////////////////////////////////////
// Helpers for implementing a QI to nsCycleCollectionParticipant
///////////////////////////////////////////////////////////////////////////////

#define NS_CYCLE_COLLECTION_INNERCLASS                                         \
        cycleCollection

#define NS_CYCLE_COLLECTION_CLASSNAME(_class)                                  \
        _class::NS_CYCLE_COLLECTION_INNERCLASS

#define NS_CYCLE_COLLECTION_NAME(_class)                                       \
        _class##_cycleCollectorGlobal

#define NS_IMPL_QUERY_CYCLE_COLLECTION(_class)                                 \
  if ( aIID.Equals(NS_GET_IID(nsCycleCollectionParticipant)) ) {               \
    foundInterface = & NS_CYCLE_COLLECTION_NAME(_class);                       \
  } else

#define NS_IMPL_QUERY_CYCLE_COLLECTION_ISUPPORTS(_class)                       \
  if ( aIID.Equals(NS_GET_IID(nsCycleCollectionISupports)) )                   \
    foundInterface = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this);      \
  else

#define NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION(_class)                        \
  NS_IMPL_QUERY_CYCLE_COLLECTION(_class)

#define NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_ISUPPORTS(_class)              \
  NS_IMPL_QUERY_CYCLE_COLLECTION_ISUPPORTS(_class)

#define NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION(_class)                      \
  NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION(_class)                              \
  NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_ISUPPORTS(_class)


///////////////////////////////////////////////////////////////////////////////
// Helpers for implementing nsCycleCollectionParticipant::Unlink
///////////////////////////////////////////////////////////////////////////////

#define NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                          \
  NS_IMETHODIMP                                                                \
  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Unlink(nsISupports *s)                \
  {                                                                            \
    NS_ASSERTION(CheckForRightISupports(s),                                    \
                 "not the nsISupports pointer we expect");                     \
    _class *tmp = Downcast(s);

#define NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(_class, _base_class)   \
  NS_IMETHODIMP                                                                \
  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Unlink(nsISupports *s)                \
  {                                                                            \
    NS_ASSERTION(CheckForRightISupports(s),                                    \
                 "not the nsISupports pointer we expect");                     \
    _class *tmp = NS_STATIC_CAST(_class*, Downcast(s));                        \
    NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Unlink(s);

#define NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(_field)                       \
    tmp->_field = NULL;    

#define NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMARRAY(_field)                     \
    tmp->_field.Clear();

#define NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                    \
    return NS_OK;                                                              \
  }

#define NS_IMPL_CYCLE_COLLECTION_UNLINK_0(_class)                              \
  NS_IMETHODIMP                                                                \
  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Unlink(nsISupports *s)                \
  {                                                                            \
    NS_ASSERTION(CheckForRightISupports(s),                                    \
                 "not the nsISupports pointer we expect");                     \
    return NS_OK;                                                              \
  }


///////////////////////////////////////////////////////////////////////////////
// Helpers for implementing nsCycleCollectionParticipant::Traverse
///////////////////////////////////////////////////////////////////////////////

#define NS_IMPL_CYCLE_COLLECTION_DESCRIBE(_class)                              \
    cb.DescribeNode(tmp->mRefCnt.get(), sizeof(_class), #_class);

#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class)                        \
  NS_IMETHODIMP                                                                \
  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Traverse                              \
                         (nsISupports *s,                                      \
                          nsCycleCollectionTraversalCallback &cb)              \
  {                                                                            \
    NS_ASSERTION(CheckForRightISupports(s),                                    \
                 "not the nsISupports pointer we expect");                     \
    _class *tmp = Downcast(s);                                                 \
    NS_IMPL_CYCLE_COLLECTION_DESCRIBE(_class)

#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(_class, _base_class) \
  NS_IMETHODIMP                                                                \
  NS_CYCLE_COLLECTION_CLASSNAME(_class)::Traverse                              \
                         (nsISupports *s,                                      \
                          nsCycleCollectionTraversalCallback &cb)              \
  {                                                                            \
    NS_ASSERTION(CheckForRightISupports(s),                                    \
                 "not the nsISupports pointer we expect");                     \
    _class *tmp = NS_STATIC_CAST(_class*, Downcast(s));                        \
    NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Traverse(s, cb);

#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_RAWPTR(_field)                       \
    cb.NoteXPCOMChild(tmp->_field);

#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(_field)                     \
    cb.NoteXPCOMChild(tmp->_field.get());

#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR_AMBIGUOUS(_field, _base)    \
    cb.NoteXPCOMChild(NS_ISUPPORTS_CAST(_base*, tmp->_field));

#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMARRAY(_field)                   \
    {                                                                          \
      PRInt32 i;                                                               \
      for (i = 0; i < tmp->_field.Count(); ++i)                                \
        cb.NoteXPCOMChild(tmp->_field[i]);                                     \
    }

#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END                                  \
    return NS_OK;                                                              \
  }

///////////////////////////////////////////////////////////////////////////////
// Helpers for implementing a concrete nsCycleCollectionParticipant 
///////////////////////////////////////////////////////////////////////////////

#define NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(_class, _base)                \
class NS_CYCLE_COLLECTION_INNERCLASS                                           \
 : public nsCycleCollectionParticipant                                         \
{                                                                              \
public:                                                                        \
  NS_IMETHOD Unlink(nsISupports *n);                                           \
  NS_IMETHOD Traverse(nsISupports *n,                                          \
                      nsCycleCollectionTraversalCallback &cb);                 \
  NS_IMETHOD_(void) UnmarkPurple(nsISupports *n)                               \
  {                                                                            \
    Downcast(n)->UnmarkPurple();                                               \
  }                                                                            \
  static _class* Downcast(nsISupports* s)                                      \
  {                                                                            \
    return NS_STATIC_CAST(_class*, NS_STATIC_CAST(_base*, s));                 \
  }                                                                            \
  static nsISupports* Upcast(_class *p)                                        \
  {                                                                            \
    return NS_ISUPPORTS_CAST(_base*, p);                                       \
  }                                                                            \
};                                                           

#define NS_DECL_CYCLE_COLLECTION_CLASS(_class)                                 \
  NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(_class, _class)

#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(_class, _base_class)          \
class NS_CYCLE_COLLECTION_INNERCLASS                                           \
 : public NS_CYCLE_COLLECTION_CLASSNAME(_base_class)                           \
{                                                                              \
public:                                                                        \
  NS_IMETHOD Unlink(nsISupports *n);                                           \
  NS_IMETHOD Traverse(nsISupports *n,                                          \
                      nsCycleCollectionTraversalCallback &cb);                 \
  static _class* Downcast(nsISupports* s)                                      \
  {                                                                            \
    return NS_STATIC_CAST(_class*, NS_STATIC_CAST(_base_class*,                \
      NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Downcast(s)));               \
  }                                                                            \
};

#define NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED_NO_UNLINK(_class,             \
                                                           _base_class)        \
class NS_CYCLE_COLLECTION_INNERCLASS                                           \
 : public NS_CYCLE_COLLECTION_CLASSNAME(_base_class)                           \
{                                                                              \
public:                                                                        \
  NS_IMETHOD Traverse(nsISupports *n,                                          \
                      nsCycleCollectionTraversalCallback &cb);                 \
  static _class* Downcast(nsISupports* s)                                      \
  {                                                                            \
    return NS_STATIC_CAST(_class*, NS_STATIC_CAST(_base_class*,                \
      NS_CYCLE_COLLECTION_CLASSNAME(_base_class)::Downcast(s)));               \
  }                                                                            \
};

/**
 * This implements a stub UnmarkPurple function for classes that want to be
 * traversed but whose AddRef/Release functions don't add/remove them to/from
 * the purple buffer. If you're just using NS_DECL_CYCLE_COLLECTING_ISUPPORTS
 * then you don't need this.
 */
#define NS_DECL_CYCLE_COLLECTION_UNMARK_PURPLE_STUB(_class)                    \
  void UnmarkPurple()                                                          \
  {                                                                            \
  }                                                                            \

#define NS_IMPL_CYCLE_COLLECTION_CLASS(_class)                                 \
  static NS_CYCLE_COLLECTION_CLASSNAME(_class)                                 \
    NS_CYCLE_COLLECTION_NAME(_class);

#define NS_IMPL_CYCLE_COLLECTION_0(_class)                                     \
 NS_IMPL_CYCLE_COLLECTION_CLASS(_class)                                        \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                 \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                           \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class)                               \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

#define NS_IMPL_CYCLE_COLLECTION_1(_class, _f)                                 \
 NS_IMPL_CYCLE_COLLECTION_CLASS(_class)                                        \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                 \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(_f)                                  \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                           \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class)                               \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(_f)                                \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

#define NS_IMPL_CYCLE_COLLECTION_2(_class, _f1, _f2)                           \
 NS_IMPL_CYCLE_COLLECTION_CLASS(_class)                                        \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                 \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(_f1)                                 \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(_f2)                                 \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                           \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class)                               \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(_f1)                               \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(_f2)                               \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

#define NS_IMPL_CYCLE_COLLECTION_3(_class, _f1, _f2, _f3)                      \
 NS_IMPL_CYCLE_COLLECTION_CLASS(_class)                                        \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(_class)                                 \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(_f1)                                 \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(_f2)                                 \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMPTR(_f3)                                 \
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END                                           \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(_class)                               \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(_f1)                               \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(_f2)                               \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(_f3)                               \
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END

#endif // nsCycleCollectionParticipant_h__