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#ifndef ubi_sLinkList_H
#define ubi_sLinkList_H
/* ========================================================================== **
* ubi_sLinkList.h
*
* Copyright (C) 1997, 1998 by Christopher R. Hertel
*
* Email: crh@ubiqx.mn.org
* -------------------------------------------------------------------------- **
* This module implements a simple singly-linked list.
* -------------------------------------------------------------------------- **
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* -------------------------------------------------------------------------- **
*
* Log: ubi_sLinkList.h,v
* Revision 0.5 1998/05/20 04:38:05 crh
* The C file now includes ubi_null.h. See ubi_null.h for more info.
*
* Revision 0.4 1998/03/10 02:22:39 crh
* Combined ubi_StackQueue and ubi_sLinkList into one module. Redesigned
* the functions and macros. Not a complete rewrite but close to it.
*
* Revision 0.3 1998/01/03 02:00:02 crh
* Added ubi_slCount() macro.
*
* Revision 0.2 1997/10/21 03:36:14 crh
* Added parameter <After> in function Insert(). Made necessary changes
* to macro AddHead() and added macro AddHere().
*
* Revision 0.1 1997/10/16 02:54:08 crh
* Initial Revision.
*
* -------------------------------------------------------------------------- **
* This module implements a singly-linked list which may also be used as a
* queue or a stack. For a queue, entries are added at the tail and removed
* from the head of the list. For a stack, the entries are entered and
* removed from the head of the list. A traversal of the list will always
* start at the head of the list and proceed toward the tail. This is all
* mind-numbingly simple, but I'm surprised by the number of programs out
* there which re-implement this a dozen or so times.
*
* Note: When the list header is initialized, the Tail pointer is set to
* point to the Head pointer. This simplifies things a great deal,
* except that you can't initialize a stack or queue by simply
* zeroing it out. One sure way to initialize the header is to call
* ubi_slInit(). Another option would be something like this:
*
* static ubi_slList MyList = { NULL, (ubi_slNodePtr)&MyList, 0 };
*
* See ubi_slInit() and the ubi_slList structure for more info.
*
* + Also, note that this module is similar to the ubi_dLinkList
* module. There are three key differences:
* - This is a singly-linked list, the other is a doubly-linked
* list.
* - In this module, if the list is empty, the tail pointer will
* point back to the head of the list as described above. This
* is not done in ubi_dLinkList.
* - The ubi_slRemove() function, by necessity, removed the 'next'
* node. In ubi_dLinkList, the ubi_dlRemove() function removes
* the 'current' node.
*
* ========================================================================== **
*/
/* ========================================================================== **
* Typedefs...
*
* ubi_slNode - This is the basic node structure.
* ubi_slNodePtr - Pointer to a node.
* ubi_slList - This is the list header structure.
* ubi_slListPtr - Pointer to a List (i.e., a list header structure).
*
*/
typedef struct ubi_slListNode
{
struct ubi_slListNode *Next;
} ubi_slNode;
typedef ubi_slNode *ubi_slNodePtr;
typedef struct
{
ubi_slNodePtr Head;
ubi_slNodePtr Tail;
unsigned long count;
} ubi_slList;
typedef ubi_slList *ubi_slListPtr;
/* ========================================================================== **
* Macros...
*
* ubi_slCount - Returns the current number of entries in the list.
*
* ubi_slAddHead - Add a new node at the head of the list.
* ubi_slAddNext - Add a new node following the indicated node.
* ubi_slAddTail - Add a new node to the tail of the list.
* Note: AddTail evaluates the L parameter twice.
*
* ubi_slRemHead - Remove the node at the head of the list, if any.
* ubi_slRemNext - Remove the node following the given node.
*
* ubi_slFirst - Return a pointer to the first node in the list, if any.
* ubi_slNext - Given a node, return a pointer to the next node.
* ubi_slLast - Return a pointer to the last node in the list, if any.
*
* ubi_slPush - Add a node at the head of the list (synonym of AddHead).
* ubi_slPop - Remove a node at the head of the list (synonym of RemHead).
* ubi_slEnqueue - Add a node at the tail of the list (sysnonym of AddTail).
* ubi_slDequeue - Remove a node at the head of the list (synonym of RemHead).
*
* Note that all of these provide type casting of the parameters. The
* Add and Rem macros are nothing more than nice front-ends to the
* Insert and Remove functions.
*
* Also note that there the First, Next and Last macros do no parameter
* checking!
*
*/
#define ubi_slCount( L ) (((ubi_slListPtr)(L))->count)
#define ubi_slAddHead( L, N ) \
ubi_slInsert( (ubi_slListPtr)(L), (ubi_slNodePtr)(N), NULL )
#define ubi_slAddNext( L, N, A ) \
ubi_slInsert( (ubi_slListPtr)(L), \
(ubi_slNodePtr)(N), \
(ubi_slNodePtr)(A) )
#define ubi_slAddTail( L, N ) \
ubi_slInsert( (ubi_slListPtr)(L), \
(ubi_slNodePtr)(N), \
((ubi_slListPtr)(L))->Tail )
#define ubi_slRemHead( L ) ubi_slRemove( (ubi_slListPtr)(L), NULL )
#define ubi_slRemNext( L, N ) \
ubi_slRemove( (ubi_slListPtr)(L), (ubi_slNodePtr)(N) )
#define ubi_slFirst( L ) (((ubi_slListPtr)(L))->Head)
#define ubi_slNext( N ) (((ubi_slNodePtr)(N))->Next)
#define ubi_slLast( L ) (((ubi_slListPtr)(L))->Tail)
#define ubi_slPush ubi_slAddHead
#define ubi_slPop ubi_slRemHead
#define ubi_slEnqueue ubi_slAddTail
#define ubi_slDequeue ubi_slRemHead
/* ========================================================================== **
* Function prototypes...
*/
ubi_slListPtr ubi_slInitList( ubi_slListPtr ListPtr );
/* ------------------------------------------------------------------------ **
* Initialize a singly-linked list header.
*
* Input: ListPtr - A pointer to the list structure that is to be
* initialized for use.
*
* Output: A pointer to the initialized list header (i.e., same as
* <ListPtr>).
*
* ------------------------------------------------------------------------ **
*/
ubi_slNodePtr ubi_slInsert( ubi_slListPtr ListPtr,
ubi_slNodePtr New,
ubi_slNodePtr After );
/* ------------------------------------------------------------------------ **
* Add a node to the list.
*
* Input: ListPtr - A pointer to the list into which the node is to
* be inserted.
* New - Pointer to the node that is to be added to the list.
* After - Pointer to a list in a node after which the new node
* will be inserted. If NULL, then the new node will
* be added at the head of the list.
*
* Output: A pointer to the node that was inserted into the list (i.e.,
* the same as <New>).
*
* ------------------------------------------------------------------------ **
*/
ubi_slNodePtr ubi_slRemove( ubi_slListPtr ListPtr, ubi_slNodePtr After );
/* ------------------------------------------------------------------------ **
* Remove the node followng <After>. If <After> is NULL, remove from the
* head of the list.
*
* Input: ListPtr - A pointer to the list from which the node is to be
* removed.
* After - Pointer to the node preceeding the node to be
* removed.
*
* Output: A pointer to the node that was removed, or NULL if the list is
* empty.
*
* ------------------------------------------------------------------------ **
*/
/* ================================ The End ================================= */
#endif /* ubi_sLinkList_H */
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