XrdOucDLlist.hh

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00001 #ifndef __OUC_DLIST__
00002 #define __OUC_DLIST__
00003 /******************************************************************************/
00004 /*                                                                            */
00005 /*                       X r d O u c D L l i s t . h h                        */
00006 /*                                                                            */
00007 /*(c) 2003 by the Board of Trustees of the Leland Stanford, Jr., University   */
00008 /*                         All Rights Reserved                                */
00009 /*Produced by Andrew Hanushevsky for Stanford University under contract       */
00010 /*           DE-AC02-76-SFO0515 with the Deprtment of Energy                  */
00011 /*                                                                            */
00012 /* This file is part of the XRootD software suite.                            */
00013 /*                                                                            */
00014 /* XRootD is free software: you can redistribute it and/or modify it under    */
00015 /* the terms of the GNU Lesser General Public License as published by the     */
00016 /* Free Software Foundation, either version 3 of the License, or (at your     */
00017 /* option) any later version.                                                 */
00018 /*                                                                            */
00019 /* XRootD is distributed in the hope that it will be useful, but WITHOUT      */
00020 /* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or      */
00021 /* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public       */
00022 /* License for more details.                                                  */
00023 /*                                                                            */
00024 /* You should have received a copy of the GNU Lesser General Public License   */
00025 /* along with XRootD in a file called COPYING.LESSER (LGPL license) and file  */
00026 /* COPYING (GPL license).  If not, see <http://www.gnu.org/licenses/>.        */
00027 /*                                                                            */
00028 /* The copyright holder's institutional names and contributor's names may not */
00029 /* be used to endorse or promote products derived from this software without  */
00030 /* specific prior written permission of the institution or contributor.       */
00031 /******************************************************************************/
00032   
00033 
00034 template<class T>
00035 class XrdOucDLlist
00036 {
00037 public:
00038 
00039          XrdOucDLlist(T *itemval=0) {prev=this; next=this; item=itemval;}
00040         ~XrdOucDLlist() {if (prev != next) Remove();}
00041 
00042 // Apply() applies the specified function to every item in the list. Apply()
00043 //         is pointer-safe in that the current node pointers may be changed
00044 //         without affecting the traversal of the list. An argument may be
00045 //         passed to the function. A null pointer is returned if the list
00046 //         was completely traversed. Otherwise, the pointer to the node on
00047 //         which the applied function returned a non-zero value is returned.
00048 //         An optional starting point may be passed.
00049 //
00050 T       *Apply(int (*func)(T *, void *), void *Arg, XrdOucDLlist *Start=0)
00051          {XrdOucDLlist *nextnode, *node;
00052           if (Start) node = Start;   // Set correct starting point
00053              else    node = this;
00054 
00055           // Iterate through the list until we hit ourselves again. We do the 
00056           // loop once on the current node to allow for anchorless lists.
00057           //
00058              do {nextnode = node->next;
00059                  if (node->item && (*func)(node->item, Arg)) return node->item;
00060                  node = nextnode;
00061                 } while (node != this);
00062 
00063          // All done, indicate we went through the whole list
00064          //
00065          return (T *)0;
00066         }
00067 
00068 // Insert() inserts the specified node immediately off itself. If an item value
00069 //          is not given, it is not changed.
00070 //
00071 void Insert(XrdOucDLlist *Node, T *Item=0)
00072                   {Node->next  = next;        // Chain in the item;
00073                    next->prev  = Node;
00074                    next        = Node;
00075                    Node->prev  = this;
00076                    if (Item) Node->item = Item;
00077                   }
00078 
00079 // Item() supplies the item value associated with itself (used with Next()).
00080 //
00081 T  *Item() {return item;}
00082 
00083 // Remove() removes itself from whatever list it happens to be in.
00084 //
00085 void Remove()
00086                   {prev->next = next;                // Unchain the item
00087                    next->prev = prev;
00088                    next       = this;
00089                    prev       = this;
00090                   }
00091 
00092 // Next() supplies the next list node.
00093 //
00094 XrdOucDLlist *Next() {return next;}
00095 
00096 // Prev() supplies the prev list node.
00097 //
00098 XrdOucDLlist *Prev() {return prev;}
00099 
00100 // Set the item pointer
00101 //
00102 void setItem(T *ival) {item = ival;}
00103 
00104 // Singleton() indicates whether or not the node points to something
00105 //
00106 int          Singleton() {return next == this;}
00107 
00108 private:
00109 XrdOucDLlist *next;
00110 XrdOucDLlist *prev;
00111 T            *item;
00112 };
00113 #endif

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