gecko-dev/xpcom/base/nsAgg.h

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#ifndef nsAgg_h___
#define nsAgg_h___

#include "nsISupports.h"


////////////////////////////////////////////////////////////////////////////////

// Put this in your class's declaration:
#define NS_DECL_AGGREGATED                                                  \
    NS_DECL_ISUPPORTS                                                       \
                                                                            \
public:                                                                     \
                                                                            \
    /**                                                                     \
     * Returns the nsISupports pointer of the inner object (aka the         \
     * aggregatee). This pointer is really only useful to the outer object  \
     * (aka the aggregator), which can use it to hold on to the inner       \
     * object. Anything else wants the nsISupports pointer of the outer     \
     * object (gotten by QI'ing inner or outer to nsISupports). This method \
     * returns a non-addrefed pointer.                                      \
     * @return the nsISupports pointer of the inner object                  \
     */                                                                     \
    nsISupports* InnerObject(void) { return &fAggregated; }                 \
                                                                            \
private:                                                                    \
                                                                            \
    /* You must implement this operation instead of the nsISupports */      \
    /* methods. */                                                          \
    nsresult                                                                \
    AggregatedQueryInterface(const nsIID& aIID, void** aInstancePtr);       \
                                                                            \
    class Internal : public nsISupports {                                   \
    public:                                                                 \
                                                                            \
        Internal() {}                                                       \
                                                                            \
        NS_IMETHOD QueryInterface(const nsIID& aIID, void** aInstancePtr);  \
        NS_IMETHOD_(nsrefcnt) AddRef(void);                                 \
        NS_IMETHOD_(nsrefcnt) Release(void);                                \
                                                                            \
    };                                                                      \
                                                                            \
    friend class Internal;                                                  \
                                                                            \
    nsISupports*        fOuter;                                             \
    Internal            fAggregated;                                        \
                                                                            \
public:                                                                     \


// Put this in your class's constructor:
#define NS_INIT_AGGREGATED(outer)                                           \
  PR_BEGIN_MACRO                                                            \
    fOuter = outer ? outer : &fAggregated;                                  \
  PR_END_MACRO


// Put this in your class's implementation file:
#define NS_IMPL_AGGREGATED(_class)                                          \
NS_IMETHODIMP                                                               \
_class::QueryInterface(const nsIID& aIID, void** aInstancePtr)              \
{                                                                           \
    return fOuter->QueryInterface(aIID, aInstancePtr);                      \
}                                                                           \
                                                                            \
NS_IMETHODIMP_(nsrefcnt)                                                    \
_class::AddRef(void)                                                        \
{                                                                           \
    return fOuter->AddRef();                                                \
}                                                                           \
                                                                            \
NS_IMETHODIMP_(nsrefcnt)                                                    \
_class::Release(void)                                                       \
{                                                                           \
    return fOuter->Release();                                               \
}                                                                           \
                                                                            \
NS_IMETHODIMP                                                               \
_class::Internal::QueryInterface(const nsIID& aIID, void** aInstancePtr)    \
{                                                                           \
    _class* agg = (_class*)((char*)(this) - offsetof(_class, fAggregated)); \
    return agg->AggregatedQueryInterface(aIID, aInstancePtr);               \
}                                                                           \
                                                                            \
NS_IMETHODIMP_(nsrefcnt)                                                    \
_class::Internal::AddRef(void)                                              \
{                                                                           \
    _class* agg = (_class*)((char*)(this) - offsetof(_class, fAggregated)); \
    NS_PRECONDITION(PRInt32(agg->mRefCnt) >= 0, "illegal refcnt");          \
    ++agg->mRefCnt;                                                         \
    NS_LOG_ADDREF(this, agg->mRefCnt, #_class, sizeof(*this));              \
    return agg->mRefCnt;                                                    \
}                                                                           \
                                                                            \
NS_IMETHODIMP_(nsrefcnt)                                                    \
_class::Internal::Release(void)                                             \
{                                                                           \
    _class* agg = (_class*)((char*)(this) - offsetof(_class, fAggregated)); \
    NS_PRECONDITION(0 != agg->mRefCnt, "dup release");                      \
    --agg->mRefCnt;                                                         \
    NS_LOG_RELEASE(this, agg->mRefCnt, #_class);                            \
    if (agg->mRefCnt == 0) {                                                \
        agg->mRefCnt = 1; /* stabilize */                                   \
        NS_DELETEXPCOM(agg);                                                \
        return 0;                                                           \
    }                                                                       \
    return agg->mRefCnt;                                                    \
}                                                                           \

// for use with QI macros in nsISupportsUtils.h:

#define NS_INTERFACE_MAP_BEGIN_AGGREGATED(_class)                           \
  NS_IMPL_AGGREGATED_QUERY_HEAD(_class)

#define NS_IMPL_AGGREGATED_QUERY_HEAD(_class)                               \
nsresult                                                                    \
_class::AggregatedQueryInterface(REFNSIID aIID, void** aInstancePtr)        \
{                                                                           \
  NS_ASSERTION(aInstancePtr,                                                \
               "AggregatedQueryInterface requires a non-NULL result ptr!"); \
  if ( !aInstancePtr )                                                      \
    return NS_ERROR_NULL_POINTER;                                           \
  nsISupports* foundInterface;                                              \
  if ( aIID.Equals(NS_GET_IID(nsISupports)) )                               \
    foundInterface = InnerObject();                                         \
  else

#define NS_GENERIC_AGGREGATED_CONSTRUCTOR(_InstanceClass)                   \
static NS_METHOD                                                            \
_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID,             \
                            void **aResult)                                 \
{                                                                           \
    *aResult = nsnull;                                                      \
                                                                            \
    NS_ENSURE_PROPER_AGGREGATION(aOuter, aIID);                             \
                                                                            \
    _InstanceClass* inst = new _InstanceClass(aOuter);                      \
    if (!inst) {                                                            \
        return NS_ERROR_OUT_OF_MEMORY;                                      \
    }                                                                       \
                                                                            \
    nsISupports* inner = inst->InnerObject();                               \
    nsresult rv = inner->QueryInterface(aIID, aResult);                     \
    if (NS_FAILED(rv)) {                                                    \
        delete inst;                                                        \
    }                                                                       \
                                                                            \
    return rv;                                                              \
}                                                                           \

#define NS_GENERIC_AGGREGATED_CONSTRUCTOR_INIT(_InstanceClass, _InitMethod) \
static NS_METHOD                                                            \
_InstanceClass##Constructor(nsISupports *aOuter, REFNSIID aIID,             \
                            void **aResult)                                 \
{                                                                           \
    *aResult = nsnull;                                                      \
                                                                            \
    NS_ENSURE_PROPER_AGGREGATION(aOuter, aIID);                             \
                                                                            \
    _InstanceClass* inst = new _InstanceClass(aOuter);                      \
    if (!inst) {                                                            \
        return NS_ERROR_OUT_OF_MEMORY;                                      \
    }                                                                       \
                                                                            \
    nsISupports* inner = inst->InnerObject();                               \
    NS_ADDREF(inner);                                                       \
    nsresult rv = inst->_InitMethod();                                      \
    if (NS_SUCCEEDED(rv)) {                                                 \
        rv = inner->QueryInterface(aIID, aResult);                          \
    }                                                                       \
    NS_RELEASE(inner);                                                      \
                                                                            \
    return rv;                                                              \
}                                                                           \

#endif /* nsAgg_h___ */