source/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 0.9  1998/07/24 07:30:20  crh
  31  * Added the ubi_slNewList() macro.
  32  *
  33  * Revision 0.8  1998/06/04 21:29:27  crh
  34  * Upper-cased defined constants (eg UBI_BINTREE_H) in some header files.
  35  * This is more "standard", and is what people expect.  Weird, eh?
  36  *
  37  * Revision 0.7  1998/06/03 18:06:03  crh
  38  * Further fiddling with sys_include.h, which has been moved from the .c file
  39  * to the .h file.
  40  *
  41  * Revision 0.6  1998/06/02 01:38:47  crh
  42  * Changed include file name from ubi_null.h to sys_include.h to make it
  43  * more generic.
  44  *
  45  * Revision 0.5  1998/05/20 04:38:05  crh
  46  * The C file now includes ubi_null.h.  See ubi_null.h for more info.
  47  *
  48  * Revision 0.4  1998/03/10 02:22:39  crh
  49  * Combined ubi_StackQueue and ubi_sLinkList into one module.  Redesigned
  50  * the functions and macros.  Not a complete rewrite but close to it.
  51  *
  52  * Revision 0.3  1998/01/03 02:00:02  crh
  53  * Added ubi_slCount() macro.
  54  *
  55  * Revision 0.2  1997/10/21 03:36:14  crh
  56  * Added parameter <After> in function Insert().  Made necessary changes
  57  * to macro AddHead() and added macro AddHere().
  58  *
  59  * Revision 0.1  1997/10/16 02:54:08  crh
  60  * Initial Revision.
  61  *
  62  * -------------------------------------------------------------------------- **
  63  *  This module implements a singly-linked list which may also be used as a
  64  *  queue or a stack.  For a queue, entries are added at the tail and removed
  65  *  from the head of the list.  For a stack, the entries are entered and
  66  *  removed from the head of the list.  A traversal of the list will always
  67  *  start at the head of the list and proceed toward the tail.  This is all
  68  *  mind-numbingly simple, but I'm surprised by the number of programs out
  69  *  there which re-implement this a dozen or so times.
  70  *
  71  *  Note:  When the list header is initialized, the Tail pointer is set to
  72  *         point to the Head pointer.  This simplifies things a great deal,
  73  *         except that you can't initialize a stack or queue by simply
  74  *         zeroing it out.  One sure way to initialize the header is to call
  75  *         ubi_slInit().  Another option would be something like this:
  76  *
  77  *           ubi_slNewList( MyList );
  78  *
  79  *         Which translates to:
  80  *
  81  *           ubi_slList MyList[1] = { NULL, (ubi_slNodePtr)MyList, 0 };
  82  *
  83  *         See ubi_slInit(), ubi_slNewList(), and the ubi_slList structure
  84  *         for more info.
  85  *
  86  *        + Also, note that this module is similar to the ubi_dLinkList
  87  *          module.  There are three key differences:
  88  *          - This is a singly-linked list, the other is a doubly-linked
  89  *            list.
  90  *          - In this module, if the list is empty, the tail pointer will
  91  *            point back to the head of the list as described above.  This
  92  *            is not done in ubi_dLinkList.
  93  *          - The ubi_slRemove() function, by necessity, removed the 'next'
  94  *            node.  In ubi_dLinkList, the ubi_dlRemove() function removes
  95  *            the 'current' node.
  96  *
  97  * ========================================================================== **
  98  */
  99
 100 #include "sys_include.h"    /* System-specific includes. */
 101
 102 /* ========================================================================== **
 103  * Typedefs...
 104  *
 105  *  ubi_slNode    - This is the basic node structure.
 106  *  ubi_slNodePtr - Pointer to a node.
 107  *  ubi_slList    - This is the list header structure.
 108  *  ubi_slListPtr - Pointer to a List (i.e., a list header structure).
 109  *
 110  */
 111
 112 typedef struct ubi_slListNode
 113   {
 114   struct ubi_slListNode *Next;
 115   } ubi_slNode;
 116
 117 typedef ubi_slNode *ubi_slNodePtr;
 118
 119 typedef struct
 120   {
 121   ubi_slNodePtr Head;
 122   ubi_slNodePtr Tail;
 123   unsigned long count;
 124   } ubi_slList;
 125
 126 typedef ubi_slList *ubi_slListPtr;
 127
 128
 129 /* ========================================================================== **
 130  * Macros...
 131  *
 132  *  ubi_slNewList - Macro used to declare and initialize a list header in
 133  *                  one step.
 134  *
 135  *  ubi_slCount   - Returns the current number of entries in the list.
 136  *
 137  *  ubi_slAddHead - Add a new node at the head of the list.
 138  *  ubi_slAddNext - Add a new node following the indicated node.
 139  *  ubi_slAddTail - Add a new node to the tail of the list.
 140  *                  Note: AddTail evaluates the L parameter twice.
 141  *
 142  *  ubi_slRemHead - Remove the node at the head of the list, if any.
 143  *  ubi_slRemNext - Remove the node following the given node.
 144  *
 145  *  ubi_slFirst   - Return a pointer to the first node in the list, if any.
 146  *  ubi_slNext    - Given a node, return a pointer to the next node.
 147  *  ubi_slLast    - Return a pointer to the last node in the list, if any.
 148  *
 149  *  ubi_slPush    - Add a node at the head of the list (synonym of AddHead).
 150  *  ubi_slPop     - Remove a node at the head of the list (synonym of RemHead).
 151  *  ubi_slEnqueue - Add a node at the tail of the list (sysnonym of AddTail).
 152  *  ubi_slDequeue - Remove a node at the head of the list (synonym of RemHead).
 153  *
 154  *  Note that all of these provide type casting of the parameters.  The
 155  *  Add and Rem macros are nothing more than nice front-ends to the
 156  *  Insert and Remove functions.
 157  *
 158  *  Also note that the First, Next and Last macros do no parameter checking!
 159  *
 160  */
 161
 162 #define ubi_slNewList( L ) ubi_slList (L)[1] = {{ NULL, (ubi_slNodePtr)(L), 0 }}
 163
 164 #define ubi_slCount( L ) (((ubi_slListPtr)(L))->count)
 165
 166 #define ubi_slAddHead( L, N ) \
 167         ubi_slInsert( (ubi_slListPtr)(L), (ubi_slNodePtr)(N), NULL )
 168
 169 #define ubi_slAddNext( L, N, A ) \
 170         ubi_slInsert( (ubi_slListPtr)(L), \
 171                       (ubi_slNodePtr)(N), \
 172                       (ubi_slNodePtr)(A) )
 173
 174 #define ubi_slAddTail( L, N ) \
 175         ubi_slInsert( (ubi_slListPtr)(L), \
 176                       (ubi_slNodePtr)(N), \
 177                      ((ubi_slListPtr)(L))->Tail )
 178
 179 #define ubi_slRemHead( L ) ubi_slRemove( (ubi_slListPtr)(L), NULL )
 180
 181 #define ubi_slRemNext( L, N ) \
 182         ubi_slRemove( (ubi_slListPtr)(L), (ubi_slNodePtr)(N) )
 183
 184 #define ubi_slFirst( L ) (((ubi_slListPtr)(L))->Head)
 185
 186 #define ubi_slNext( N )  (((ubi_slNodePtr)(N))->Next)
 187
 188 #define ubi_slLast( L )  (((ubi_slListPtr)(L))->Tail)
 189
 190 #define ubi_slPush    ubi_slAddHead
 191 #define ubi_slPop     ubi_slRemHead
 192 #define ubi_slEnqueue ubi_slAddTail
 193 #define ubi_slDequeue ubi_slRemHead
 194
 195 /* ========================================================================== **
 196  * Function prototypes...
 197  */
 198
 199 ubi_slListPtr ubi_slInitList( ubi_slListPtr ListPtr );
 200   /* ------------------------------------------------------------------------ **
 201    * Initialize a singly-linked list header.
 202    *
 203    *  Input:  ListPtr - A pointer to the list structure that is to be
 204    *                    initialized for use.
 205    *
 206    *  Output: A pointer to the initialized list header (i.e., same as
 207    *          <ListPtr>).
 208    *
 209    * ------------------------------------------------------------------------ **
 210    */
 211
 212 ubi_slNodePtr ubi_slInsert( ubi_slListPtr ListPtr,
 213                             ubi_slNodePtr New,
 214                             ubi_slNodePtr After );
 215   /* ------------------------------------------------------------------------ **
 216    * Add a node to the list.
 217    *
 218    *  Input:  ListPtr - A pointer to the list into which the node is to
 219    *                    be inserted.
 220    *          New     - Pointer to the node that is to be added to the list.
 221    *          After   - Pointer to a list in a node after which the new node
 222    *                    will be inserted.  If NULL, then the new node will
 223    *                    be added at the head of the list.
 224    *
 225    *  Output: A pointer to the node that was inserted into the list (i.e.,
 226    *          the same as <New>).
 227    *
 228    * ------------------------------------------------------------------------ **
 229    */
 230
 231 ubi_slNodePtr ubi_slRemove( ubi_slListPtr ListPtr, ubi_slNodePtr After );
 232   /* ------------------------------------------------------------------------ **
 233    * Remove the node followng <After>.  If <After> is NULL, remove from the
 234    * head of the list.
 235    *
 236    *  Input:  ListPtr - A pointer to the list from which the node is to be
 237    *                    removed.
 238    *          After   - Pointer to the node preceeding the node to be
 239    *                    removed.
 240    *
 241    *  Output: A pointer to the node that was removed, or NULL if the list is
 242    *          empty.
 243    *
 244    * ------------------------------------------------------------------------ **
 245    */
 246
 247 /* ================================ The End ================================= */
 248 #endif /* UBI_SLINKLIST_H */