source3/ubiqx/ubi_sLinkList.h

   1 #ifndef UBI_SLINKLIST_H
   2 #define UBI_SLINKLIST_H
   3 /* ========================================================================== **
   4  *                              ubi_sLinkList.h
   5  *
   6  *  Copyright (C) 1997, 1998 by Christopher R. Hertel
   7  *
   8  *  Email: crh@ubiqx.mn.org
   9  * -------------------------------------------------------------------------- **
  10  *  This module implements a simple singly-linked list.
  11  * -------------------------------------------------------------------------- **
  12  *
  13  *  This library is free software; you can redistribute it and/or
  14  *  modify it under the terms of the GNU Library General Public
  15  *  License as published by the Free Software Foundation; either
  16  *  version 2 of the License, or (at your option) any later version.
  17  *
  18  *  This library is distributed in the hope that it will be useful,
  19  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  21  *  Library General Public License for more details.
  22  *
  23  *  You should have received a copy of the GNU Library General Public
  24  *  License along with this library; if not, write to the Free
  25  *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  26  *
  27  * -------------------------------------------------------------------------- **
  28  *
  29  * Log: ubi_sLinkList.h,v
  30  * Revision 0.10  1999/06/19 16:58:06  crh
  31  * Renamed the ubi_slRemove() function in ubi_sLinkList to
  32  * ubi_slRemoveNext().  I was bothered by the fact that it didn't
  33  * match the functionality of the ubi_dlRemove() function in
  34  * ubi_dLinkList.  The new name is more 'correct'.
  35  *
  36  * Revision 0.9  1998/07/24 07:30:20  crh
  37  * Added the ubi_slNewList() macro.
  38  *
  39  * Revision 0.8  1998/06/04 21:29:27  crh
  40  * Upper-cased defined constants (eg UBI_BINTREE_H) in some header files.
  41  * This is more "standard", and is what people expect.  Weird, eh?
  42  *
  43  * Revision 0.7  1998/06/03 18:06:03  crh
  44  * Further fiddling with sys_include.h, which has been moved from the .c file
  45  * to the .h file.
  46  *
  47  * Revision 0.6  1998/06/02 01:38:47  crh
  48  * Changed include file name from ubi_null.h to sys_include.h to make it
  49  * more generic.
  50  *
  51  * Revision 0.5  1998/05/20 04:38:05  crh
  52  * The C file now includes ubi_null.h.  See ubi_null.h for more info.
  53  *
  54  * Revision 0.4  1998/03/10 02:22:39  crh
  55  * Combined ubi_StackQueue and ubi_sLinkList into one module.  Redesigned
  56  * the functions and macros.  Not a complete rewrite but close to it.
  57  *
  58  * Revision 0.3  1998/01/03 02:00:02  crh
  59  * Added ubi_slCount() macro.
  60  *
  61  * Revision 0.2  1997/10/21 03:36:14  crh
  62  * Added parameter <After> in function Insert().  Made necessary changes
  63  * to macro AddHead() and added macro AddHere().
  64  *
  65  * Revision 0.1  1997/10/16 02:54:08  crh
  66  * Initial Revision.
  67  *
  68  * -------------------------------------------------------------------------- **
  69  *  This module implements a singly-linked list which may also be used as a
  70  *  queue or a stack.  For a queue, entries are added at the tail and removed
  71  *  from the head of the list.  For a stack, the entries are entered and
  72  *  removed from the head of the list.  A traversal of the list will always
  73  *  start at the head of the list and proceed toward the tail.  This is all
  74  *  mind-numbingly simple, but I'm surprised by the number of programs out
  75  *  there which re-implement this a dozen or so times.
  76  *
  77  *  Note:  When the list header is initialized, the Tail pointer is set to
  78  *         point to the Head pointer.  This simplifies things a great deal,
  79  *         except that you can't initialize a stack or queue by simply
  80  *         zeroing it out.  One sure way to initialize the header is to call
  81  *         ubi_slInit().  Another option would be something like this:
  82  *
  83  *           ubi_slNewList( MyList );
  84  *
  85  *         Which translates to:
  86  *
  87  *           ubi_slList MyList[1] = { NULL, (ubi_slNodePtr)MyList, 0 };
  88  *
  89  *         See ubi_slInit(), ubi_slNewList(), and the ubi_slList structure
  90  *         for more info.
  91  *
  92  *        + Also, note that this module is similar to the ubi_dLinkList
  93  *          module.  There are three key differences:
  94  *          - This is a singly-linked list, the other is a doubly-linked
  95  *            list.
  96  *          - In this module, if the list is empty, the tail pointer will
  97  *            point back to the head of the list as described above.  This
  98  *            is not done in ubi_dLinkList.
  99  *          - The ubi_slRemoveNext() function, by necessity, removes the
 100  *            'next' node.  In ubi_dLinkList, the ubi_dlRemove() function
 101  *            removes the 'current' node.
 102  *
 103  * ========================================================================== **
 104  */
 105
 106 #include "sys_include.h"    /* System-specific includes. */
 107
 108 /* ========================================================================== **
 109  * Typedefs...
 110  *
 111  *  ubi_slNode    - This is the basic node structure.
 112  *  ubi_slNodePtr - Pointer to a node.
 113  *  ubi_slList    - This is the list header structure.
 114  *  ubi_slListPtr - Pointer to a List (i.e., a list header structure).
 115  *
 116  */
 117
 118 typedef struct ubi_slListNode
 119   {
 120   struct ubi_slListNode *Next;
 121   } ubi_slNode;
 122
 123 typedef ubi_slNode *ubi_slNodePtr;
 124
 125 typedef struct
 126   {
 127   ubi_slNodePtr Head;
 128   ubi_slNodePtr Tail;
 129   unsigned long count;
 130   } ubi_slList;
 131
 132 typedef ubi_slList *ubi_slListPtr;
 133
 134
 135 /* ========================================================================== **
 136  * Macros...
 137  *
 138  *  ubi_slNewList - Macro used to declare and initialize a list header in
 139  *                  one step.
 140  *
 141  *  ubi_slCount   - Returns the current number of entries in the list.
 142  *
 143  *  ubi_slAddHead - Add a new node at the head of the list.
 144  *  ubi_slAddNext - Add a new node following the indicated node.
 145  *  ubi_slAddTail - Add a new node to the tail of the list.
 146  *                  Note: AddTail evaluates the L parameter twice.
 147  *
 148  *  ubi_slRemHead - Remove the node at the head of the list, if any.
 149  *  ubi_slRemNext - Remove the node following the given node.
 150  *
 151  *  ubi_slFirst   - Return a pointer to the first node in the list, if any.
 152  *  ubi_slNext    - Given a node, return a pointer to the next node.
 153  *  ubi_slLast    - Return a pointer to the last node in the list, if any.
 154  *
 155  *  ubi_slPush    - Add a node at the head of the list (synonym of AddHead).
 156  *  ubi_slPop     - Remove a node at the head of the list (synonym of RemHead).
 157  *  ubi_slEnqueue - Add a node at the tail of the list (sysnonym of AddTail).
 158  *  ubi_slDequeue - Remove a node at the head of the list (synonym of RemHead).
 159  *
 160  *  Note that all of these provide type casting of the parameters.  The
 161  *  Add and Rem macros are nothing more than nice front-ends to the
 162  *  Insert and Remove functions.
 163  *
 164  *  Also note that the First, Next and Last macros do no parameter checking!
 165  *
 166  */
 167
 168 #define ubi_slNewList( L ) ubi_slList (L)[1] = {{ NULL, (ubi_slNodePtr)(L), 0 }}
 169
 170 #define ubi_slCount( L ) (((ubi_slListPtr)(L))->count)
 171
 172 #define ubi_slAddHead( L, N ) \
 173         ubi_slInsert( (ubi_slListPtr)(L), (ubi_slNodePtr)(N), NULL )
 174
 175 #define ubi_slAddNext( L, N, A ) \
 176         ubi_slInsert( (ubi_slListPtr)(L), \
 177                       (ubi_slNodePtr)(N), \
 178                       (ubi_slNodePtr)(A) )
 179
 180 #define ubi_slAddTail( L, N ) \
 181         ubi_slInsert( (ubi_slListPtr)(L), \
 182                       (ubi_slNodePtr)(N), \
 183                      ((ubi_slListPtr)(L))->Tail )
 184
 185 #define ubi_slRemHead( L ) ubi_slRemoveNext( (ubi_slListPtr)(L), NULL )
 186
 187 #define ubi_slRemNext( L, N ) \
 188         ubi_slRemoveNext( (ubi_slListPtr)(L), (ubi_slNodePtr)(N) )
 189
 190 #define ubi_slFirst( L ) (((ubi_slListPtr)(L))->Head)
 191
 192 #define ubi_slNext( N )  (((ubi_slNodePtr)(N))->Next)
 193
 194 #define ubi_slLast( L )  (((ubi_slListPtr)(L))->Tail)
 195
 196 #define ubi_slPush    ubi_slAddHead
 197 #define ubi_slPop     ubi_slRemHead
 198 #define ubi_slEnqueue ubi_slAddTail
 199 #define ubi_slDequeue ubi_slRemHead
 200
 201 /* ========================================================================== **
 202  * Function prototypes...
 203  */
 204
 205 ubi_slListPtr ubi_slInitList( ubi_slListPtr ListPtr );
 206   /* ------------------------------------------------------------------------ **
 207    * Initialize a singly-linked list header.
 208    *
 209    *  Input:  ListPtr - A pointer to the list structure that is to be
 210    *                    initialized for use.
 211    *
 212    *  Output: A pointer to the initialized list header (i.e., same as
 213    *          <ListPtr>).
 214    *
 215    * ------------------------------------------------------------------------ **
 216    */
 217
 218 ubi_slNodePtr ubi_slInsert( ubi_slListPtr ListPtr,
 219                             ubi_slNodePtr New,
 220                             ubi_slNodePtr After );
 221   /* ------------------------------------------------------------------------ **
 222    * Add a node to the list.
 223    *
 224    *  Input:  ListPtr - A pointer to the list into which the node is to
 225    *                    be inserted.
 226    *          New     - Pointer to the node that is to be added to the list.
 227    *          After   - Pointer to a list in a node after which the new node
 228    *                    will be inserted.  If NULL, then the new node will
 229    *                    be added at the head of the list.
 230    *
 231    *  Output: A pointer to the node that was inserted into the list (i.e.,
 232    *          the same as <New>).
 233    *
 234    * ------------------------------------------------------------------------ **
 235    */
 236
 237 ubi_slNodePtr ubi_slRemoveNext( ubi_slListPtr ListPtr, ubi_slNodePtr AfterMe );
 238   /* ------------------------------------------------------------------------ **
 239    * Remove the node followng <AfterMe>.  If <AfterMe> is NULL, remove from
 240    * the head of the list.
 241    *
 242    *  Input:  ListPtr - A pointer to the list from which the node is to be
 243    *                    removed.
 244    *          AfterMe - Pointer to the node preceeding the node to be
 245    *                    removed.
 246    *
 247    *  Output: A pointer to the node that was removed, or NULL if the list is
 248    *          empty.
 249    *
 250    * ------------------------------------------------------------------------ **
 251    */
 252
 253 /* ================================ The End ================================= */
 254 #endif /* UBI_SLINKLIST_H */