added wxObject::AllocExclusive() and associated methods

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@13937 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/object.h

@@ -382,18 +382,33 @@ public:
     virtual void Dump(wxSTD ostream& str);
 #endif
 
-        // make a 'clone' of the object
+    // ref counted data handling methods
 
+    // get/set
+    wxObjectRefData *GetRefData() const { return m_refData; }
+    void SetRefData(wxObjectRefData *data) { m_refData = data; }
+
+    // make a 'clone' of the object
     void Ref(const wxObject& clone);
 
     // destroy a reference
-  
     void UnRef();
 
-    inline wxObjectRefData *GetRefData() const { return m_refData; }
-    inline void SetRefData(wxObjectRefData *data) { m_refData = data; }
-
 protected:
+    // ensure that our data is not shared with anybody else: if we have no
+    // data, it is created using CreateRefData() below, if we have shared data
+    // it is copied using CloneRefData(), otherwise nothing is done
+    void AllocExclusive();
+
+    // both methods must be implemented if Unshare() is used, not pure virtual
+    // only because of the backwards compatibility reasons
+
+    // create a new m_refData
+    virtual wxObjectRefData *CreateRefData() const;
+
+    // create a new m_refData initialized with the given one
+    virtual wxObjectRefData *CloneRefData(wxObjectRefData *data) const;
+
     wxObjectRefData *m_refData;
 };
 

src/common/object.cpp

@@ -249,10 +249,44 @@ void wxObject::UnRef()
 
         if ( !--m_refData->m_count )
             delete m_refData;
-        m_refData = 0;
+        m_refData = NULL;
     }
 }
 
+void wxObject::AllocExclusive()
+{
+    if ( !m_refData )
+    {
+        m_refData = CreateRefData();
+    }
+    else if ( m_refData->GetRefCount() > 1 )
+    {
+        // note that ref is not going to be destroyed in this case
+        wxObjectRefData* ref = m_refData;
+        UnRef();
+
+        // ... so we can still access it
+        m_refData = CloneRefData(ref);
+    }
+    //else: ref count is 1, we are exclusive owners of m_refData anyhow
+
+    wxASSERT_MSG( m_refData && m_refData->GetRefCount() == 1,
+                  _T("wxObject::AllocExclusive() failed.") );
+}
+
+wxObjectRefData *wxObject::CreateRefData() const
+{
+    return NULL;
+}
+
+wxObjectRefData *wxObject::CloneRefData(wxObjectRefData * WXUNUSED(data)) const
+{
+    return NULL;
+}
+
+// ----------------------------------------------------------------------------
+// misc
+// ----------------------------------------------------------------------------
 
 #if defined(__DARWIN__) && defined(DYLIB_INIT)