// $Id: listitem.h 751 2006-03-31 15:43:49Z alex $ /* @@tag:xara-cn@@ DO NOT MODIFY THIS LINE ================================XARAHEADERSTART=========================== Xara LX, a vector drawing and manipulation program. Copyright (C) 1993-2006 Xara Group Ltd. Copyright on certain contributions may be held in joint with their respective authors. See AUTHORS file for details. LICENSE TO USE AND MODIFY SOFTWARE ---------------------------------- This file is part of Xara LX. Xara LX is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License version 2 as published by the Free Software Foundation. Xara LX and its component source files are distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. 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Xara Group Ltd, Gaddesden Place, Hemel Hempstead, HP2 6EX, UK. http://www.xara.com/ =================================XARAHEADEREND============================ */ /* */ /********************************************************************************************** > class ListItem : public CCObject Author: Mario_Shamtani (Xara Group Ltd) Created: 13/4/1993 Base Class: CObject Purpose: A list item is an abstract class which is used to derive all objects which are linked together in lists. It has no member functions because all useful operations are defined in the List class. The reason for doing this is that list operations may need to alter the list header. Errors: None. **********************************************************************************************/ /* Technical notes: When using lists with derived listitems it is necessary to explicitly cast from a listitem pointer to the 'derived listitem' pointer. e.g. List x; MyListItem* y; .... y = x.GetHead(); // Wrong!!! need to cast to MyListItem* because // GetHead() returns a ListItem* y = (MyListItem*) x.GetHead(); // This will work honest! (This is only necesary when retrieving items from the list because type convertion from a derived class to a base class is automatic.) You also have to do the cast if the function call is nested within another function call. e.g. void Display(MyListItem*); .... Display(x.GetHead()); // Error! .... Display((MyListItem*)x.GetHead()); // OK! **********************************************************************************************/ #ifndef INC_LISTITEM #define INC_LISTITEM #include "ccobject.h" class CCAPI ListItem : public CCObject { CC_DECLARE_DYNCREATE(ListItem); friend class List; // The class list is a friend of // ListItem friend class ActionList; // ActionList is also a friend private: ListItem *Next; // Pointer to NEXT ListItem in List ListItem *Previous; // " " PREVIOUS ListItem " " public: ListItem(); virtual ~ListItem() {} // base classes must have a virtual destructor virtual ListItem *GetItem(void); // For compatability with OrderedList // traversal methods virtual void ClearPointers(); }; #endif