include/wx/itemid.h

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/itemid.h
   3 // Purpose:     wxItemId class declaration.
   4 // Author:      Vadim Zeitlin
   5 // Created:     2011-08-17
   6 // Copyright:   (c) 2011 Vadim Zeitlin <vadim@wxwidgets.org>
   7 // Licence:     wxWindows licence
   8 ///////////////////////////////////////////////////////////////////////////////
   9
  10 #ifndef _WX_ITEMID_H_
  11 #define _WX_ITEMID_H_
  12
  13 // ----------------------------------------------------------------------------
  14 // wxItemId: an opaque item identifier used with wx{Tree,TreeList,DataView}Ctrl.
  15 // ----------------------------------------------------------------------------
  16
  17 // The template argument T is typically a pointer to some opaque type. While
  18 // wxTreeItemId and wxDataViewItem use a pointer to void, this is dangerous and
  19 // not recommended for the new item id classes.
  20 template <typename T>
  21 class wxItemId
  22 {
  23 public:
  24     typedef T Type;
  25
  26     // This ctor is implicit which is fine for non-void* types, but if you use
  27     // this class with void* you're strongly advised to make the derived class
  28     // ctor explicit as implicitly converting from any pointer is simply too
  29     // dangerous.
  30     wxItemId(Type item = NULL) : m_pItem(item) { }
  31
  32     // Default copy ctor, assignment operator and dtor are ok.
  33
  34     bool IsOk() const { return m_pItem != NULL; }
  35     Type GetID() const { return m_pItem; }
  36     operator const Type() const { return m_pItem; }
  37
  38     // This is used for implementation purposes only.
  39     Type operator->() const { return m_pItem; }
  40
  41     void Unset() { m_pItem = NULL; }
  42
  43     // This field is public *only* for compatibility with the old wxTreeItemId
  44     // implementation and must not be used in any new code.
  45 //private:
  46     Type m_pItem;
  47 };
  48
  49 template <typename T>
  50 bool operator==(const wxItemId<T>& left, const wxItemId<T>& right)
  51 {
  52     return left.GetID() == right.GetID();
  53 }
  54
  55 template <typename T>
  56 bool operator!=(const wxItemId<T>& left, const wxItemId<T>& right)
  57 {
  58     return !(left == right);
  59 }
  60
  61 #endif // _WX_ITEMID_H_