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

14 files changed, 42 insertions, 0 deletions

diff --git a/src/corelib/tools/qbytearray.cpp b/src/corelib/tools/qbytearray.cpp
index bf9b6bd..e43c2b5 100644
--- a/src/corelib/tools/qbytearray.cpp
+++ b/src/corelib/tools/qbytearray.cpp
@@ -1048,6 +1048,11 @@ QByteArray &QByteArray::operator=(const char *str)
     \internal
 */
 
+/*! \fn bool QByteArray::isSharedWith(const QByteArray &other)
+
+    \internal
+*/
+
 /*! \fn char QByteArray::at(int i) const
 
     Returns the character at index position \a i in the byte array.
diff --git a/src/corelib/tools/qbytearray.h b/src/corelib/tools/qbytearray.h
index 7dd6f4f..ba344cb 100644
--- a/src/corelib/tools/qbytearray.h
+++ b/src/corelib/tools/qbytearray.h
@@ -164,6 +164,7 @@ public:
     inline const char *constData() const;
     inline void detach();
     bool isDetached() const;
+    inline bool isSharedWith(const QByteArray &other) const { return d == other.d; }
     void clear();
 
 #ifdef Q_COMPILER_MANGLES_RETURN_TYPE
diff --git a/src/corelib/tools/qhash.cpp b/src/corelib/tools/qhash.cpp
index c82c389..a616ac2 100644
--- a/src/corelib/tools/qhash.cpp
+++ b/src/corelib/tools/qhash.cpp
@@ -847,6 +847,11 @@ void QHashData::checkSanity()
     \internal
 */
 
+/*! \fn bool QHash::isSharedWith(const QHash<Key, T> &other) const
+
+    \internal
+*/
+
 /*! \fn void QHash::clear()
 
     Removes all items from the hash.
diff --git a/src/corelib/tools/qhash.h b/src/corelib/tools/qhash.h
index 2de03dc..66e9cde 100644
--- a/src/corelib/tools/qhash.h
+++ b/src/corelib/tools/qhash.h
@@ -299,6 +299,7 @@ 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 QHash<Key, T> &other) const { return d == other.d; }
 
     void clear();
 
diff --git a/src/corelib/tools/qlinkedlist.cpp b/src/corelib/tools/qlinkedlist.cpp
index 281508e..987e538 100644
--- a/src/corelib/tools/qlinkedlist.cpp
+++ b/src/corelib/tools/qlinkedlist.cpp
@@ -197,6 +197,11 @@ QLinkedListData QLinkedListData::shared_null = {
     \internal
 */
 
+/*! \fn bool QLinkedList::isSharedWith(const QLinkedList<T> &other) const
+
+    \internal
+*/
+
 /*! \fn bool QLinkedList::isEmpty() const
 
     Returns true if the list contains no items; otherwise returns
diff --git a/src/corelib/tools/qlinkedlist.h b/src/corelib/tools/qlinkedlist.h
index e119a50..395adf2 100644
--- a/src/corelib/tools/qlinkedlist.h
+++ b/src/corelib/tools/qlinkedlist.h
@@ -93,6 +93,7 @@ public:
     { 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 QLinkedList<T> &other) const { return d == other.d; }
 
     inline bool isEmpty() const { return d->size == 0; }
 
diff --git a/src/corelib/tools/qlist.cpp b/src/corelib/tools/qlist.cpp
index 9b20c82..da93d5f 100644
--- a/src/corelib/tools/qlist.cpp
+++ b/src/corelib/tools/qlist.cpp
@@ -599,6 +599,11 @@ void **QListData::erase(void **xi)
     \internal
 */
 
+/*! \fn bool QList::isSharedWith(const QList<T> &other) const
+
+    \internal
+*/
+
 /*! \fn bool QList::isEmpty() const
 
     Returns true if the list contains no items; otherwise returns
diff --git a/src/corelib/tools/qlist.h b/src/corelib/tools/qlist.h
index 49b5c0d..e65ee15 100644
--- a/src/corelib/tools/qlist.h
+++ b/src/corelib/tools/qlist.h
@@ -130,6 +130,7 @@ public:
 
     inline bool isDetached() const { return d->ref == 1; }
     inline void setSharable(bool sharable) { if (!sharable) detach(); d->sharable = sharable; }
+    inline bool isSharedWith(const QList<T> &other) const { return d == other.d; }
 
     inline bool isEmpty() const { return p.isEmpty(); }
 
diff --git a/src/corelib/tools/qmap.cpp b/src/corelib/tools/qmap.cpp
index 3b48c3f..432b5a5 100644
--- a/src/corelib/tools/qmap.cpp
+++ b/src/corelib/tools/qmap.cpp
@@ -473,6 +473,11 @@ void QMapData::dump()
     \internal
 */
 
+/*! \fn bool QMap::isSharedWith(const QMap<Key, T> &other) const
+
+    \internal
+*/
+
 /*! \fn void QMap::setInsertInOrder(bool sharable)
 
     \internal
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();
diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp
index 98d88ac..f3355df 100644
--- a/src/corelib/tools/qstring.cpp
+++ b/src/corelib/tools/qstring.cpp
@@ -1097,6 +1097,11 @@ QString::QString(QChar ch)
     \internal
 */
 
+/*! \fn bool QString::isSharedWith(const QString &other) const
+
+    \internal
+*/
+
 // ### Qt 5: rename freeData() to avoid confusion. See task 197625.
 void QString::free(Data *d)
 {
diff --git a/src/corelib/tools/qstring.h b/src/corelib/tools/qstring.h
index 668be35..c6fd80a 100644
--- a/src/corelib/tools/qstring.h
+++ b/src/corelib/tools/qstring.h
@@ -122,6 +122,7 @@ public:
 
     inline void detach();
     inline bool isDetached() const;
+    inline bool isSharedWith(const QString &other) const { return d == other.d; }
     void clear();
 
     inline const QChar at(int i) const;
diff --git a/src/corelib/tools/qvector.cpp b/src/corelib/tools/qvector.cpp
index 8bb1074..00d663b 100644
--- a/src/corelib/tools/qvector.cpp
+++ b/src/corelib/tools/qvector.cpp
@@ -392,6 +392,11 @@ int QVectorData::grow(int sizeofTypedData, int size, int sizeofT, bool excessive
     \internal
 */
 
+/*! \fn bool QVector::isSharedWith(const QVector<T> &other) const
+
+    \internal
+*/
+
 /*! \fn T *QVector::data()
 
     Returns a pointer to the data stored in the vector. The pointer
diff --git a/src/corelib/tools/qvector.h b/src/corelib/tools/qvector.h
index e00cf3f..043617f 100644
--- a/src/corelib/tools/qvector.h
+++ b/src/corelib/tools/qvector.h
@@ -134,6 +134,7 @@ 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 QVector<T> &other) const { return d == other.d; }
 
     inline T *data() { detach(); return p->array; }
     inline const T *data() const { return p->array; }