diff options
Diffstat (limited to 'src/corelib/tools/qsharedpointer_impl.h')
| -rw-r--r-- | src/corelib/tools/qsharedpointer_impl.h | 80 |
1 files changed, 61 insertions, 19 deletions
diff --git a/src/corelib/tools/qsharedpointer_impl.h b/src/corelib/tools/qsharedpointer_impl.h index 8a343620b..cbeb79ff3 100644 --- a/src/corelib/tools/qsharedpointer_impl.h +++ b/src/corelib/tools/qsharedpointer_impl.h @@ -34,7 +34,7 @@ ** met: http://www.gnu.org/copyleft/gpl.html. ** ** If you are unsure which license is appropriate for your use, please -** contact the sales department at http://www.qtsoftware.com/contact. +** contact the sales department at http://qt.nokia.com/contact. ** $QT_END_LICENSE$ ** ****************************************************************************/ @@ -115,12 +115,22 @@ 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 { typedef T *Basic:: *RestrictedBool; public: typedef T Type; + typedef T element_type; + typedef T value_type; + typedef value_type *pointer; + typedef const value_type *const_pointer; + typedef value_type &reference; + typedef const value_type &const_reference; + typedef ptrdiff_t difference_type; inline T *data() const { return value; } inline bool isNull() const { return !data(); } @@ -148,6 +158,12 @@ 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; @@ -161,6 +177,9 @@ namespace QtSharedPointer { 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 @@ -171,18 +190,8 @@ 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 *); @@ -197,13 +206,26 @@ 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) { @@ -211,7 +233,7 @@ namespace QtSharedPointer { executeDeleter(realself->extra.ptr, realself->extra.deleter); // delete the deleter too - realself->extra.~Next(); + realself->extra.~CustomDeleter(); } static void safetyCheckDeleter(ExternalRefCountData *self) { @@ -229,8 +251,8 @@ 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; } @@ -240,6 +262,10 @@ 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 { @@ -282,6 +308,8 @@ 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> { @@ -490,6 +518,14 @@ class QWeakPointer typedef QtSharedPointer::ExternalRefCountData Data; public: + typedef T element_type; + typedef T value_type; + typedef value_type *pointer; + typedef const value_type *const_pointer; + typedef value_type &reference; + typedef const value_type &const_reference; + typedef ptrdiff_t difference_type; + inline bool isNull() const { return d == 0 || d->strongref == 0 || value == 0; } inline operator RestrictedBool() const { return isNull() ? 0 : &QWeakPointer::value; } inline bool operator !() const { return isNull(); } @@ -634,6 +670,12 @@ bool operator!=(const QSharedPointer<T> &ptr1, const QWeakPointer<X> &ptr2) return ptr2 != ptr1; } +template <class T, class X> +Q_INLINE_TEMPLATE typename T::difference_type operator-(const QSharedPointer<T> &ptr1, const QSharedPointer<X> &ptr2) +{ + return ptr1.data() - ptr2.data(); +} + template <class T> Q_INLINE_TEMPLATE QWeakPointer<T> QSharedPointer<T>::toWeakRef() const { |