add {QString,QByteArray,QList,QLinkedList,QHash,QMap,QVector}::isSharedWith()

these functions just compare the d pointers of two objects. this can be
used to verify the validity of cached data: you keep a copy of the
original data in your cache. consequently, any changes to the original
data must detach, so this function reflects whether the cached data is
still up-to-date.
of course, this is not thread safe, as the data might change right after
you check it, but that's a general problem of cache coherency which
needs to be handled further up the stack.

the functions are internal because the other detaching-related functions
are internal as well for reasons beyond me.

Reviewed-by: brad

1 files changed, 1 insertions, 0 deletions

diff --git a/src/corelib/tools/qmap.h b/src/corelib/tools/qmap.h
index 0441107..ce97178 100644
--- a/src/corelib/tools/qmap.h
+++ b/src/corelib/tools/qmap.h
@@ -182,6 +182,7 @@ public:
     inline void detach() { if (d->ref != 1) detach_helper(); }
     inline bool isDetached() const { return d->ref == 1; }
     inline void setSharable(bool sharable) { if (!sharable) detach(); d->sharable = sharable; }
+    inline bool isSharedWith(const QMap<Key, T> &other) const { return d == other.d; }
     inline void setInsertInOrder(bool ordered) { d->insertInOrder = ordered; }
 
     void clear();