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#ifndef nsCycleCollector_h__
#define nsCycleCollector_h__

// NOTE: If you use header files to define DEBUG_CC, you must do so here
// *and* in nsCycleCollectionParticipant.h
//#define DEBUG_CC

class nsISupports;
class nsCycleCollectionParticipant;
class nsCycleCollectionTraversalCallback;

// An nsCycleCollectionLanguageRuntime is a per-language object that
// implements language-specific aspects of the cycle collection task.

struct nsCycleCollectionLanguageRuntime
{
    virtual nsresult BeginCycleCollection(nsCycleCollectionTraversalCallback &cb) = 0;
    virtual nsresult FinishCycleCollection() = 0;
    virtual nsCycleCollectionParticipant *ToParticipant(void *p) = 0;
#ifdef DEBUG_CC
    virtual void PrintAllReferencesTo(void *p) = 0;
#endif
};

nsresult nsCycleCollector_startup();
// Returns the number of collected nodes.
NS_COM PRUint32 nsCycleCollector_collect();
NS_COM PRUint32 nsCycleCollector_suspectedCount();
void nsCycleCollector_shutdown();

// The JS runtime is special, it needs to call cycle collection during its GC.
// If the JS runtime is registered nsCycleCollector_collect will call
// nsCycleCollectionJSRuntime::Collect which will call
// nsCycleCollector_doCollect, else nsCycleCollector_collect will call
// nsCycleCollector_doCollect directly.
struct nsCycleCollectionJSRuntime : public nsCycleCollectionLanguageRuntime
{
    /**
     * Runs cycle collection and returns whether cycle collection collected
     * anything.
     */
    virtual PRBool Collect() = 0;
};
// Returns PR_TRUE if cycle collection was started.
NS_COM PRBool nsCycleCollector_beginCollection();
// Returns PR_TRUE if some nodes were collected. Should only be called after
// nsCycleCollector_beginCollection() returned PR_TRUE.
NS_COM PRBool nsCycleCollector_finishCollection();

#ifdef DEBUG
NS_COM void nsCycleCollector_DEBUG_shouldBeFreed(nsISupports *n);
NS_COM void nsCycleCollector_DEBUG_wasFreed(nsISupports *n);
#endif

// Helpers for interacting with language-identified scripts

NS_COM void nsCycleCollector_registerRuntime(PRUint32 langID, nsCycleCollectionLanguageRuntime *rt);
NS_COM void nsCycleCollector_forgetRuntime(PRUint32 langID);

#endif // nsCycleCollector_h__