diff options
Diffstat (limited to 'src/corelib/tools/qsharedpointer_impl.h')
| -rw-r--r-- | src/corelib/tools/qsharedpointer_impl.h | 76 |
1 files changed, 56 insertions, 20 deletions
diff --git a/src/corelib/tools/qsharedpointer_impl.h b/src/corelib/tools/qsharedpointer_impl.h index e381433..bce4c64 100644 --- a/src/corelib/tools/qsharedpointer_impl.h +++ b/src/corelib/tools/qsharedpointer_impl.h @@ -115,6 +115,9 @@ namespace QtSharedPointer { template <class T> struct RemovePointer<QSharedPointer<T> > { typedef T Type; }; template <class T> struct RemovePointer<QWeakPointer<T> > { typedef T Type; }; + // This class provides the basic functionality of a pointer wrapper. + // Its existence is mostly legacy, since originally QSharedPointer + // could also be used for internally-refcounted objects. template <class T> class Basic { @@ -161,6 +164,12 @@ namespace QtSharedPointer { Type *value; }; + // This class is the d-pointer of QSharedPointer and QWeakPointer. + // + // It is a reference-counted reference counter. "strongref" is the inner + // reference counter, and it tracks the lifetime of the pointer itself. + // "weakref" is the outer reference counter and it tracks the lifetime of + // the ExternalRefCountData object. struct ExternalRefCountData { QBasicAtomicInt weakref; @@ -168,12 +177,15 @@ namespace QtSharedPointer { inline ExternalRefCountData() { - QBasicAtomicInt proto = Q_BASIC_ATOMIC_INITIALIZER(1); - weakref = strongref = proto; + strongref = 1; + weakref = 1; } inline ExternalRefCountData(Qt::Initialization) { } virtual inline ~ExternalRefCountData() { Q_ASSERT(!weakref); Q_ASSERT(strongref <= 0); } + // overridden by derived classes + // returns false to indicate caller should delete the pointer + // returns true in case it has already done so virtual inline bool destroy() { return false; } #ifndef QT_NO_QOBJECT @@ -184,18 +196,8 @@ namespace QtSharedPointer { }; // sizeof(ExternalRefCount) = 12 (32-bit) / 16 (64-bit) - template <class T, typename Deleter> - struct CustomDeleter - { - Deleter deleter; - T *ptr; - - inline CustomDeleter(T *p, Deleter d) : deleter(d), ptr(p) {} - }; - // sizeof(CustomDeleter) = sizeof(Deleter) + sizeof(void*) - // for Deleter = function pointer: 8 (32-bit) / 16 (64-bit) - // for Deleter = PMF: 12 (32-bit) / 24 (64-bit) (GCC) - + // This class extends ExternalRefCountData with a pointer + // to a function, which is called by the destroy() function. struct ExternalRefCountWithDestroyFn: public ExternalRefCountData { typedef void (*DestroyerFn)(ExternalRefCountData *); @@ -210,13 +212,26 @@ namespace QtSharedPointer { }; // sizeof(ExternalRefCountWithDestroyFn) = 16 (32-bit) / 24 (64-bit) + // This class extends ExternalRefCountWithDestroyFn and implements + // the static function that deletes the object. The pointer and the + // custom deleter are kept in the "extra" member. template <class T, typename Deleter> struct ExternalRefCountWithCustomDeleter: public ExternalRefCountWithDestroyFn { typedef ExternalRefCountWithCustomDeleter Self; - typedef ExternalRefCountWithDestroyFn Parent; - typedef CustomDeleter<T, Deleter> Next; - Next extra; + typedef ExternalRefCountWithDestroyFn BaseClass; + + struct CustomDeleter + { + Deleter deleter; + T *ptr; + + inline CustomDeleter(T *p, Deleter d) : deleter(d), ptr(p) {} + }; + CustomDeleter extra; + // sizeof(CustomDeleter) = sizeof(Deleter) + sizeof(void*) + // for Deleter = function pointer: 8 (32-bit) / 16 (64-bit) + // for Deleter = PMF: 12 (32-bit) / 24 (64-bit) (GCC) static inline void deleter(ExternalRefCountData *self) { @@ -224,7 +239,7 @@ namespace QtSharedPointer { executeDeleter(realself->extra.ptr, realself->extra.deleter); // delete the deleter too - realself->extra.~Next(); + realself->extra.~CustomDeleter(); } static void safetyCheckDeleter(ExternalRefCountData *self) { @@ -242,8 +257,8 @@ namespace QtSharedPointer { Self *d = static_cast<Self *>(::operator new(sizeof(Self))); // initialize the two sub-objects - new (&d->extra) Next(ptr, userDeleter); - new (d) Parent(destroy); // can't throw + new (&d->extra) CustomDeleter(ptr, userDeleter); + new (d) BaseClass(destroy); // can't throw return d; } @@ -253,6 +268,10 @@ namespace QtSharedPointer { ~ExternalRefCountWithCustomDeleter(); }; + // This class extends ExternalRefCountWithDestroyFn and adds a "T" + // member. That way, when the create() function is called, we allocate + // memory for both QSharedPointer's d-pointer and the actual object being + // tracked. template <class T> struct ExternalRefCountWithContiguousData: public ExternalRefCountWithDestroyFn { @@ -295,6 +314,8 @@ namespace QtSharedPointer { ~ExternalRefCountWithContiguousData(); }; + // This is the main body of QSharedPointer. It implements the + // external reference counting functionality. template <class T> class ExternalRefCount: public Basic<T> { @@ -370,6 +391,12 @@ namespace QtSharedPointer { delete this->value; } + inline void internalSwap(ExternalRefCount &other) + { + qSwap(d, other.d); + qSwap(this->value, other.value); + } + #if defined(Q_NO_TEMPLATE_FRIENDS) public: #else @@ -450,6 +477,9 @@ public: inline QSharedPointer<T> &operator=(const QWeakPointer<X> &other) { BaseClass::internalSet(other.d, other.value); return *this; } + inline void swap(QSharedPointer &other) + { internalSwap(other); } + template <class X> QSharedPointer<X> staticCast() const { @@ -673,6 +703,12 @@ Q_INLINE_TEMPLATE QWeakPointer<T> QSharedPointer<T>::toWeakRef() const return QWeakPointer<T>(*this); } +template <class T> +inline void qSwap(QSharedPointer<T> &p1, QSharedPointer<T> &p2) +{ + p1.swap(p2); +} + namespace QtSharedPointer { // helper functions: template <class X, class T> |