zephyr/zwgc/stack.h

   1 /* This file is part of the Project Athena Zephyr Notification System.
   2  * It is one of the source files comprising zwgc, the Zephyr WindowGram
   3  * client.
   4  *
   5  *      Created by:     Marc Horowitz <marc@athena.mit.edu>
   6  *
   7  *      $Id$
   8  *
   9  *      Copyright (c) 1989 by the Massachusetts Institute of Technology.
  10  *      For copying and distribution information, see the file
  11  *      "mit-copyright.h".
  12  */
  13
  14
  15 #include <zephyr/mit-copyright.h>
  16
  17 /****************************************************************************/
  18 /*                                                                          */
  19 /*               A generic stack type based on linked lists:                */
  20 /*                                                                          */
  21 /****************************************************************************/
  22
  23 #ifndef TYPE_T_stack_TYPE
  24 #define TYPE_T_stack_TYPE
  25
  26 #ifndef  NULL
  27 #define  NULL 0
  28 #endif
  29
  30 typedef struct _TYPE_T_stack {
  31     struct _TYPE_T_stack *next;
  32     TYPE_T data;
  33 } *TYPE_T_stack;
  34
  35 #define  TYPE_T_stack_create()           ((struct _TYPE_T_stack *) NULL)
  36
  37 #define  TYPE_T_stack_empty(stack)       (!(stack))
  38
  39 #ifdef DEBUG
  40 #define  TYPE_T_stack_top(stack)         ((stack) ? (stack)->data :\
  41                                           (abort(),(stack)->data))
  42 #else
  43 #define  TYPE_T_stack_top(stack)         ((stack)->data)
  44 #endif
  45
  46 #ifdef DEBUG
  47 #define  TYPE_T_stack_pop(stack)  { TYPE_T_stack old = (stack);\
  48                                     if (!old)\
  49                                       abort(); /*<<<>>>*/\
  50                                     (stack) = old->next;\
  51                                     free(old); }
  52 #else
  53 #define  TYPE_T_stack_pop(stack)  { TYPE_T_stack old = (stack);\
  54                                     (stack) = old->next;\
  55                                     free(old); }
  56 #endif
  57
  58 #define  TYPE_T_stack_push(stack,object) \
  59            { TYPE_T_stack new = (struct _TYPE_T_stack *)\
  60                malloc(sizeof (struct _TYPE_T_stack));\
  61              new->next = (stack);\
  62              new->data = object;\
  63              (stack) = new; }
  64
  65 #endif