content/base/public/nsIDOMGCParticipant.h

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  37
  38 #ifndef nsIDOMGCParticipant_h_
  39 #define nsIDOMGCParticipant_h_
  40
  41 #include "nsISupports.h"
  42
  43 template<class E> class nsCOMArray;
  44
  45 // 0e2a5a8d-28fd-4a5c-8bf1-5b0067ff3286
  46 #define NS_IDOMGCPARTICIPANT_IID \
  47 { 0x0e2a5a8d, 0x28fd, 0x4a5c, \
  48   {0x8b, 0xf1, 0x5b, 0x00, 0x67, 0xff, 0x32, 0x86} }
  49
  50 /**
  51  * DOM GC Participants are objects that expose information about
  52  * reachability in the native object graphs to help prevent script ->
  53  * native -> script cyclical reference from causing leaks due to the
  54  * creation of garbage collection roots and native/script boundaries.
  55  *
  56  * Some implementations of nsIDOMGCParticipant may be responsible for
  57  * enforcing the requirement that callers of
  58  * |nsDOMClassInfo::PreserveWrapper| must call
  59  * |nsDOMClassInfo::ReleaseWrapper| before the nsIDOMGCParticipant
  60  * argument to the former is destroyed.
  61  */
  62 class nsIDOMGCParticipant : public nsISupports
  63 {
  64 public:
  65   NS_DECLARE_STATIC_IID_ACCESSOR(NS_IDOMGCPARTICIPANT_IID)
  66
  67   /**
  68    * Get a reference node for what is known to be a strongly connected
  69    * component of nsIDOMGCParticipants.  For example, DOM trees are
  70    * strongly connected, so can return the root node to greatly reduce
  71    * the number of nodes on which we need to run graph algorithms.
  72    *
  73    * Note that it's acceptable for nodes in a single strongly connected
  74    * component to return different values for GetSCCIndex, as long as
  75    * those two values claim that they're reachable from each other in
  76    * AppendReachableList.
  77    */
  78   virtual nsIDOMGCParticipant* GetSCCIndex() = 0;
  79
  80   /**
  81    * Append the list of nsIDOMGCPartipants reachable from this one via
  82    * C++ getters exposed to script that return a different result from
  83    * |GetSCCIndex|.  The caller is responsible for taking the transitive
  84    * closure of |AppendReachableList|.
  85    *
  86    * This will only be called on objects that are returned by GetSCCIndex.
  87    *
  88    * null pointers may be appended; they will be ignored by the caller.
  89    */
  90   virtual void AppendReachableList(nsCOMArray<nsIDOMGCParticipant>& aArray) = 0;
  91 };
  92
  93 NS_DEFINE_STATIC_IID_ACCESSOR(nsIDOMGCParticipant, NS_IDOMGCPARTICIPANT_IID)
  94
  95 #endif // !defined(nsIDOMGCParticipant_h_)