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 // RCS-ID:      $Id: wxhead.h,v 1.12 2010-04-22 12:44:51 zeitlin Exp $
   7 // Copyright:   (c) 2011 Vadim Zeitlin <vadim@wxwidgets.org>
   8 // Licence:     wxWindows licence
   9 ///////////////////////////////////////////////////////////////////////////////
  10
  11 #ifndef _WX_ITEMID_H_
  12 #define _WX_ITEMID_H_
  13
  14 // ----------------------------------------------------------------------------
  15 // wxItemId: an opaque item identifier used with wx{Tree,TreeList,DataView}Ctrl.
  16 // ----------------------------------------------------------------------------
  17
  18 // The template argument T is typically a pointer to some opaque type. While
  19 // wxTreeItemId and wxDataViewItem use a pointer to void, this is dangerous and
  20 // not recommended for the new item id classes.
  21 template <typename T>
  22 class wxItemId
  23 {
  24 public:
  25     typedef T Type;
  26
  27     // This ctor is implicit which is fine for non-void* types, but if you use
  28     // this class with void* you're strongly advised to make the derived class
  29     // ctor explicit as implicitly converting from any pointer is simply too
  30     // dangerous.
  31     wxItemId(Type item = NULL) : m_pItem(item) { }
  32
  33     // Default copy ctor, assignment operator and dtor are ok.
  34
  35     bool IsOk() const { return m_pItem != NULL; }
  36     Type GetID() const { return m_pItem; }
  37     operator const Type() const { return m_pItem; }
  38
  39     // This is used for implementation purposes only.
  40     Type operator->() const { return m_pItem; }
  41
  42     void Unset() { m_pItem = NULL; }
  43
  44     // This field is public *only* for compatibility with the old wxTreeItemId
  45     // implementation and must not be used in any new code.
  46 //private:
  47     Type m_pItem;
  48 };
  49
  50 template <typename T>
  51 bool operator==(const wxItemId<T>& left, const wxItemId<T>& right)
  52 {
  53     return left.GetID() == right.GetID();
  54 }
  55
  56 template <typename T>
  57 bool operator!=(const wxItemId<T>& left, const wxItemId<T>& right)
  58 {
  59     return !(left == right);
  60 }
  61
  62 #endif // _WX_ITEMID_H_