gecko-dev/xpcom/base/nsAgg.h

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C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef nsAgg_h___
#define nsAgg_h___
#include "nsISupports.h"
#include "nsCycleCollectionParticipant.h"
////////////////////////////////////////////////////////////////////////////////
// Put NS_DECL_AGGREGATED or NS_DECL_CYCLE_COLLECTING_AGGREGATED in your class's
// declaration.
#define NS_DECL_AGGREGATED \
NS_DECL_ISUPPORTS \
NS_DECL_AGGREGATED_HELPER
#define NS_DECL_CYCLE_COLLECTING_AGGREGATED \
NS_DECL_CYCLE_COLLECTING_ISUPPORTS \
NS_DECL_AGGREGATED_HELPER
#define NS_DECL_AGGREGATED_HELPER \
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; } \
\
/** \
* Returns true if this object is part of an aggregated object. \
*/ \
bool IsPartOfAggregated(void) { return fOuter != InnerObject(); } \
\
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) override; \
NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override; \
NS_IMETHOD_(MozExternalRefCountType) Release(void) override; \
\
NS_DECL_OWNINGTHREAD \
}; \
\
friend class Internal; \
\
nsISupports* MOZ_UNSAFE_REF( \
"fOuter can either point to fAggregated " \
"or to an outer object, and the safety " \
"of this reference depends on the exact " \
"lifetime semantics of the AddRef/Release " \
"functions created by these macros.") fOuter; \
Internal fAggregated; \
\
public:
#define NS_DECL_AGGREGATED_CYCLE_COLLECTION_CLASS(_class) \
class NS_CYCLE_COLLECTION_INNERCLASS \
: public nsXPCOMCycleCollectionParticipant { \
public: \
constexpr explicit NS_CYCLE_COLLECTION_INNERCLASS(bool aSkip = false) \
: nsXPCOMCycleCollectionParticipant(aSkip) {} \
\
NS_IMETHOD_(void) Unlink(void* p) override; \
NS_IMETHOD TraverseNative( \
void* p, nsCycleCollectionTraversalCallback& cb) override; \
NS_DECL_CYCLE_COLLECTION_CLASS_NAME_METHOD(_class) \
NS_IMETHOD_(void) DeleteCycleCollectable(void* p) override { \
NS_CYCLE_COLLECTION_CLASSNAME(_class)::Downcast( \
static_cast<nsISupports*>(p)) \
->DeleteCycleCollectable(); \
} \
static _class* Downcast(nsISupports* s) { \
return (_class*)((char*)(s)-offsetof(_class, fAggregated)); \
} \
static nsISupports* Upcast(_class* p) { return p->InnerObject(); } \
static nsXPCOMCycleCollectionParticipant* GetParticipant() { \
return &_class::NS_CYCLE_COLLECTION_INNERNAME; \
} \
}; \
NS_CHECK_FOR_RIGHT_PARTICIPANT_IMPL(_class); \
static NS_CYCLE_COLLECTION_INNERCLASS NS_CYCLE_COLLECTION_INNERNAME;
// Put this in your class's constructor:
#define NS_INIT_AGGREGATED(outer) \
do { \
fOuter = outer ? outer : &fAggregated; \
} while (0)
// Put this in your class's implementation file:
#define NS_IMPL_AGGREGATED(_class) \
\
NS_IMPL_AGGREGATED_HELPER(_class) \
\
NS_IMETHODIMP_(MozExternalRefCountType) \
_class::Internal::AddRef(void) { \
_class* agg = (_class*)((char*)(this) - offsetof(_class, fAggregated)); \
MOZ_ASSERT(int32_t(agg->mRefCnt) >= 0, "illegal refcnt"); \
NS_ASSERT_OWNINGTHREAD(_class); \
++agg->mRefCnt; \
NS_LOG_ADDREF(this, agg->mRefCnt, #_class, sizeof(*this)); \
return agg->mRefCnt; \
} \
\
NS_IMETHODIMP_(MozExternalRefCountType) \
_class::Internal::Release(void) { \
_class* agg = (_class*)((char*)(this) - offsetof(_class, fAggregated)); \
MOZ_ASSERT(int32_t(agg->mRefCnt) > 0, "dup release"); \
NS_ASSERT_OWNINGTHREAD(_class); \
--agg->mRefCnt; \
NS_LOG_RELEASE(this, agg->mRefCnt, #_class); \
if (agg->mRefCnt == 0) { \
agg->mRefCnt = 1; /* stabilize */ \
delete agg; \
return 0; \
} \
return agg->mRefCnt; \
}
#define NS_IMPL_CYCLE_COLLECTING_AGGREGATED(_class) \
\
NS_IMPL_AGGREGATED_HELPER(_class) \
\
NS_IMETHODIMP_(MozExternalRefCountType) \
_class::Internal::AddRef(void) { \
_class* agg = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Downcast(this); \
MOZ_ASSERT(int32_t(agg->mRefCnt) >= 0, "illegal refcnt"); \
NS_ASSERT_OWNINGTHREAD_AGGREGATE(agg, _class); \
nsrefcnt count = agg->mRefCnt.incr(this); \
NS_LOG_ADDREF(this, count, #_class, sizeof(*agg)); \
return count; \
} \
NS_IMETHODIMP_(MozExternalRefCountType) \
_class::Internal::Release(void) { \
_class* agg = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Downcast(this); \
MOZ_ASSERT(int32_t(agg->mRefCnt) > 0, "dup release"); \
NS_ASSERT_OWNINGTHREAD_AGGREGATE(agg, _class); \
nsrefcnt count = agg->mRefCnt.decr(this); \
NS_LOG_RELEASE(this, count, #_class); \
return count; \
} \
NS_IMETHODIMP_(void) \
_class::DeleteCycleCollectable(void) { delete this; }
#define NS_IMPL_AGGREGATED_HELPER(_class) \
NS_IMETHODIMP \
_class::QueryInterface(const nsIID& aIID, void** aInstancePtr) { \
return fOuter->QueryInterface(aIID, aInstancePtr); \
} \
\
NS_IMETHODIMP_(MozExternalRefCountType) \
_class::AddRef(void) { return fOuter->AddRef(); } \
\
NS_IMETHODIMP_(MozExternalRefCountType) \
_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); \
}
/**
* To make aggregated objects participate in cycle collection we need to enable
* the outer object (aggregator) to traverse/unlink the objects held by the
* inner object (the aggregatee). We can't just make the inner object QI'able to
* NS_CYCLECOLLECTIONPARTICIPANT_IID, we don't want to return the inner object's
* nsCycleCollectionParticipant for the outer object (which will happen if the
* outer object doesn't participate in cycle collection itself).
* NS_AGGREGATED_CYCLECOLLECTIONPARTICIPANT_IID enables the outer object to get
* the inner objects nsCycleCollectionParticipant.
*
* There are three cases:
* - No aggregation
* QI'ing to NS_CYCLECOLLECTIONPARTICIPANT_IID will return the inner
* object's nsCycleCollectionParticipant.
*
* - Aggregation and outer object does not participate in cycle collection
* QI'ing to NS_CYCLECOLLECTIONPARTICIPANT_IID will not return anything.
*
* - Aggregation and outer object does participate in cycle collection
* QI'ing to NS_CYCLECOLLECTIONPARTICIPANT_IID will return the outer
* object's nsCycleCollectionParticipant. The outer object's
* nsCycleCollectionParticipant can then QI the inner object to
* NS_AGGREGATED_CYCLECOLLECTIONPARTICIPANT_IID to get the inner object's
* nsCycleCollectionParticipant, which it can use to traverse/unlink the
* objects reachable from the inner object.
*/
#define NS_AGGREGATED_CYCLECOLLECTIONPARTICIPANT_IID \
{ \
0x32889b7e, 0xe4fe, 0x43f4, { \
0x85, 0x31, 0xb5, 0x28, 0x23, 0xa2, 0xe9, 0xfc \
} \
}
/**
* Just holds the IID so NS_GET_IID works.
*/
class nsAggregatedCycleCollectionParticipant {
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_AGGREGATED_CYCLECOLLECTIONPARTICIPANT_IID)
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsAggregatedCycleCollectionParticipant,
NS_AGGREGATED_CYCLECOLLECTIONPARTICIPANT_IID)
// for use with QI macros in nsISupportsUtils.h:
#define NS_INTERFACE_MAP_BEGIN_AGGREGATED(_class) \
NS_IMPL_AGGREGATED_QUERY_HEAD(_class)
#define NS_IMPL_QUERY_CYCLE_COLLECTION(_class) \
if (aIID.Equals(NS_GET_IID(nsXPCOMCycleCollectionParticipant))) { \
*aInstancePtr = NS_CYCLE_COLLECTION_PARTICIPANT(_class); \
return NS_OK; \
} else
#define NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_AGGREGATED(_class) \
NS_IMPL_QUERY_CYCLE_COLLECTION(_class)
#define NS_IMPL_QUERY_CYCLE_COLLECTION_ISUPPORTS(_class) \
if (aIID.Equals(NS_GET_IID(nsCycleCollectionISupports))) { \
*aInstancePtr = NS_CYCLE_COLLECTION_CLASSNAME(_class)::Upcast(this); \
return NS_OK; \
} else
#define NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_ISUPPORTS(_class) \
NS_IMPL_QUERY_CYCLE_COLLECTION_ISUPPORTS(_class)
#define NS_INTERFACE_MAP_ENTRIES_CYCLE_COLLECTION_AGGREGATED(_class) \
NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_AGGREGATED(_class) \
NS_INTERFACE_MAP_ENTRY_CYCLE_COLLECTION_ISUPPORTS(_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_IMPL_AGGREGATED_QUERY_CYCLE_COLLECTION(_class) \
if (aIID.Equals(IsPartOfAggregated() \
? NS_GET_IID(nsCycleCollectionParticipant) \
: NS_GET_IID(nsAggregatedCycleCollectionParticipant))) \
foundInterface = NS_CYCLE_COLLECTION_PARTICIPANT(_class); \
else
#define NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_AGGREGATED(_class) \
NS_IMETHODIMP \
NS_CYCLE_COLLECTION_CLASSNAME(_class)::TraverseNative( \
void* p, nsCycleCollectionTraversalCallback& cb) { \
nsISupports* s = static_cast<nsISupports*>(p); \
MOZ_ASSERT(CheckForRightISupports(s), \
"not the nsISupports pointer we expect"); \
_class* tmp = static_cast<_class*>(Downcast(s)); \
if (!tmp->IsPartOfAggregated()) \
NS_IMPL_CYCLE_COLLECTION_DESCRIBE(_class, tmp->mRefCnt.get())
#define NS_GENERIC_AGGREGATED_CONSTRUCTOR(_InstanceClass) \
static nsresult _InstanceClass##Constructor(nsISupports* aOuter, \
REFNSIID aIID, void** aResult) { \
*aResult = nullptr; \
if (NS_WARN_IF(aOuter && !aIID.Equals(NS_GET_IID(nsISupports)))) \
return NS_ERROR_INVALID_ARG; \
\
RefPtr<_InstanceClass> inst = new _InstanceClass(aOuter); \
nsISupports* inner = inst->InnerObject(); \
nsresult rv = inner->QueryInterface(aIID, aResult); \
\
return rv; \
}
#define NS_GENERIC_AGGREGATED_CONSTRUCTOR_INIT(_InstanceClass, _InitMethod) \
static nsresult _InstanceClass##Constructor(nsISupports* aOuter, \
REFNSIID aIID, void** aResult) { \
*aResult = nullptr; \
if (NS_WARN_IF(aOuter && !aIID.Equals(NS_GET_IID(nsISupports)))) \
return NS_ERROR_INVALID_ARG; \
\
RefPtr<_InstanceClass> inst = new _InstanceClass(aOuter); \
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___ */