Add qobject_cast for QSharedPointer.

This obviously only works for classes that derive from QObject. And
you must remember that QSharedPointer controls the QObject's lifetime,
not the QObject parent-child relationship.

Reviewed-by: dt
Reviewed-by: Bradley T. Hughes

1 files changed, 56 insertions, 0 deletions

diff --git a/src/corelib/tools/qsharedpointer.cpp b/src/corelib/tools/qsharedpointer.cpp
index ba62ce1..71bf318 100644
--- a/src/corelib/tools/qsharedpointer.cpp
+++ b/src/corelib/tools/qsharedpointer.cpp
@@ -340,6 +340,23 @@
 */
 
 /*!
+    \fn QSharedPointer<X> QSharedPointer::objectCast() const
+
+    Performs a \ref qobject_cast from this pointer's type to \tt X and
+    returns a QSharedPointer that shares the reference. If this
+    function is used to up-cast, then QSharedPointer will perform a \tt
+    qobject_cast, which means that if the object being pointed by this
+    QSharedPointer is not of type \tt X, the returned object will be
+    null.
+
+    Note: the template type \c X must have the same const and volatile
+    qualifiers as the template of this object, or the cast will
+    fail. Use constCast() if you need to drop those qualifiers.
+
+    \sa qSharedPointerObjectCast()
+*/
+
+/*!
     \fn QWeakPointer<T> QSharedPointer::toWeakRef() const
 
     Returns a weak reference object that shares the pointer referenced
@@ -718,6 +735,45 @@
 */
 
 /*!
+    \fn QSharedPointer<X> qSharedPointerObjectCast(const QSharedPointer<T> &other)
+    \relates QSharedPointer
+
+    Returns a shared pointer to the pointer held by \a other, using a
+    \ref qobject_cast to type \tt X to obtain an internal pointer of the
+    appropriate type. If the \tt qobject_cast fails, the object
+    returned will be null.
+
+    Note that \tt X must have the same cv-qualifiers (\tt const and
+    \tt volatile) that \tt T has, or the code will fail to
+    compile. Use qSharedPointerConstCast to cast away the constness.
+
+    \sa QSharedPointer::objectCast(), qSharedPointerCast(), qSharedPointerConstCast()
+*/
+
+/*!
+    \fn QSharedPointer<X> qSharedPointerObjectCast(const QWeakPointer<T> &other)
+    \relates QSharedPointer
+    \relates QWeakPointer
+
+    Returns a shared pointer to the pointer held by \a other, using a
+    \ref qobject_cast to type \tt X to obtain an internal pointer of the
+    appropriate type. If the \tt qobject_cast fails, the object
+    returned will be null.
+
+    The \a other object is converted first to a strong reference. If
+    that conversion fails (because the object it's pointing to has
+    already been deleted), this function also returns a null
+    QSharedPointer.
+
+    Note that \tt X must have the same cv-qualifiers (\tt const and
+    \tt volatile) that \tt T has, or the code will fail to
+    compile. Use qSharedPointerConstCast to cast away the constness.
+
+    \sa QWeakPointer::toStrongRef(), qSharedPointerCast(), qSharedPointerConstCast()
+*/
+
+
+/*!
     \fn QWeakPointer<X> qWeakPointerCast(const QWeakPointer<T> &other)
     \relates QWeakPointer