[1660792 ] wxObject::Dec/IncRef and wxObjectDataPtr

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@44521 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/latex/wx/object.tex

@@ -202,6 +202,10 @@ The {\it delete} operator is defined for debugging versions of the library only,
 the identifier \_\_WXDEBUG\_\_ is defined. It takes over memory deallocation, allowing
 wxDebugContext operations.
 
+
+
+%% wxObjectRefData
+
 \section{\class{wxObjectRefData}}\label{wxobjectrefdata}
 
 This class is used to store reference-counted data. Derive classes from this to
@@ -223,19 +227,36 @@ you will need to cast to your own derived class.
 
 \func{}{wxObjectRefData}{\void}
 
-Default constructor. Initialises the {\bf m\_count} member to 1.
+Default constructor. Initialises the internal reference count to 1.
 
 \membersection{wxObjectRefData::\destruct{wxObjectRefData}}\label{wxobjectrefdatadtor}
 
 \func{}{wxObjectRefData}{\void}
 
-Destructor.
+Destructor. It's declared {\tt protected} so that wxObjectRefData instances will never
+be destroyed directly but only as result of a \helpref{DecRef}{wxobjectrefdatadecref} call.
 
 \membersection{wxObjectRefData::GetRefCount}\label{wxobjectrefdatagetrefcount}
 
 \constfunc{int}{GetRefCount}{\void}
 
 Returns the reference count associated with this shared data.
-When this goes to zero during a \helpref{wxObject::UnRef}{wxobjectunref}, an object
+When this goes to zero during a \helpref{DecRef}{wxobjectrefdatadecref} call, the object
-can delete this {\bf wxObjectRefData} object.
+will auto-free itself.
+
+\membersection{wxObjectRefData::DecRef}\label{wxobjectrefdatadecref}
+
+\func{void}{DecRef}{\void}
+
+Decrements the reference count associated with this shared data and, if it reaches zero,
+destroys this instance of wxObjectRefData releasing its memory.
+
+Please note that after calling this function, the caller should absolutely avoid to use
+the pointer to this instance since it may not be valid anymore.
+
+\membersection{wxObjectRefData::IncRef}\label{wxobjectrefdataincref}
+
+\func{void}{IncRef}{\void}
+
+Increments the reference count associated with this shared data.
 

include/wx/object.h

@@ -392,14 +392,83 @@ class WXDLLIMPEXP_BASE wxObjectRefData
 
 public:
     wxObjectRefData() : m_count(1) { }
-    virtual ~wxObjectRefData() { }
 
     int GetRefCount() const { return m_count; }
 
+    void IncRef() { m_count++; }
+    void DecRef();
+
+protected:
+    // this object should never be destroyed directly but only as a
+    // result of a DecRef() call:
+    virtual ~wxObjectRefData() { }
+
 private:
+    // our refcount:
     int m_count;
 };
 
+// ----------------------------------------------------------------------------
+// wxObjectDataPtr: helper class to avoid memleaks because of missing calls
+//                  to wxObjectRefData::DecRef
+// ----------------------------------------------------------------------------
+
+template <class T>
+class wxObjectDataPtr
+{
+public:
+    typedef T element_type;
+
+    wxEXPLICIT wxObjectDataPtr(T *ptr = NULL) : m_ptr(ptr) {}
+
+    // copy ctor
+    wxObjectDataPtr(const wxObjectDataPtr<T> &tocopy) 
+        : m_ptr(tocopy.m_ptr)
+    { 
+        if (m_ptr)
+            m_ptr->IncRef(); 
+    }
+
+    ~wxObjectDataPtr() 
+    { 
+        if (m_ptr) 
+            m_ptr->DecRef(); 
+    }
+
+    T *get() const { return m_ptr; }
+    T *operator->() const { return get(); }
+
+    void reset(T *ptr)
+    {
+        if (m_ptr)
+            m_ptr->DecRef();
+        m_ptr = ptr;
+    }
+
+    wxObjectDataPtr& operator=(const wxObjectDataPtr &tocopy)
+    { 
+        if (m_ptr) 
+            m_ptr->DecRef(); 
+        m_ptr = tocopy.m_ptr; 
+        if (m_ptr)
+            m_ptr->IncRef(); 
+        return *this;
+    }
+
+    wxObjectDataPtr& operator=(T *ptr)
+    { 
+        if (m_ptr) 
+            m_ptr->DecRef(); 
+        m_ptr = ptr; 
+        if (m_ptr)
+            m_ptr->IncRef(); 
+        return *this;
+    }
+
+private:
+    T *m_ptr;
+};
+
 // ----------------------------------------------------------------------------
 // wxObject: the root class of wxWidgets object hierarchy
 // ----------------------------------------------------------------------------
@@ -520,7 +589,8 @@ public:
 #ifdef _MSC_VER
         return (wxClassInfo*) m_classInfo;
 #else
-        return wx_const_cast(wxClassInfo *, m_classInfo);
+        wxDynamicClassInfo *nonconst = wx_const_cast(wxDynamicClassInfo *, m_classInfo);
+        return wx_static_cast(wxClassInfo *, nonconst);
 #endif
     }
 

src/common/object.cpp

@@ -289,6 +289,17 @@ wxObject *wxCreateDynamicObject(const wxChar *name)
 }
 
 
+// ----------------------------------------------------------------------------
+// wxObjectRefData
+// ----------------------------------------------------------------------------
+
+void wxObjectRefData::DecRef()
+{
+    if ( --m_count == 0 )
+        delete this;
+}
+
+
 // ----------------------------------------------------------------------------
 // wxObject
 // ----------------------------------------------------------------------------
@@ -310,7 +321,7 @@ void wxObject::Ref(const wxObject& clone)
     if ( clone.m_refData )
     {
         m_refData = clone.m_refData;
-        ++(m_refData->m_count);
+        m_refData->IncRef();
     }
 }
 
@@ -320,8 +331,7 @@ void wxObject::UnRef()
     {
         wxASSERT_MSG( m_refData->m_count > 0, _T("invalid ref data count") );
 
-        if ( --m_refData->m_count == 0 )
+        m_refData->DecRef();
-            delete m_refData;
         m_refData = NULL;
     }
 }