lib/stack.cc

   1 /*
   2  * Copyright (C) 2004 Jesus Gimenez, Lluis Marquez and Senen Moya
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  17  */
  18
  19 #include <stdlib.h>
  20 #include <stdio.h>
  21 #include "stack.h"
  22
  23 /****************************************************************************/
  24
  25 /*
  26  * empty -- Indica si la pila est  vac¡a o no
  27  * Parametros:
  28  *      *ps: puntero a la pila
  29  * Devuelve:
  30  *      TRUE si est  vac¡a FALSE si no lo est
  31  */
  32 boolean empty(struct stack_t *ps)
  33 {
  34         return((boolean)(ps->top == -1));
  35 }
  36
  37 /****************************************************************************/
  38
  39 /*
  40  * init_stack -- Inicializa la pila
  41  * Parametros:
  42  *              *ps: puntero a la pila
  43  */
  44 void init_stack(struct stack_t *ps)
  45 {
  46         ps->top = -1;
  47 }
  48
  49 /****************************************************************************/
  50
  51 /*
  52  * pop -- Extrae el elemento del top de la pila si no est  vac¡a
  53  * Parametros:
  54  *      *ps: puntero a la pila
  55  * Devuelve:
  56  *      El elemento del top de la pila si no est  vac¡a
  57  */
  58 element_type pop(struct stack_t *ps)
  59 {
  60         if (empty(ps))  return NULL;
  61         return(ps->items[ps->top--]);
  62 }
  63
  64 /****************************************************************************/
  65
  66 /*
  67  * push -- Coloca un valor en la pila
  68  * Parametros:
  69  *      *ps: puntero a la pila
  70  *      x: valor a colocar en la pila
  71  */
  72 void push(struct stack_t *ps, element_type x)
  73 {
  74         if (ps->top == STACKSIZE -1) {
  75                 fprintf(stderr,"Error: Stack Overflow. %d %d\n",ps->top,STACKSIZE-1);
  76                 exit(1);
  77         }
  78         else
  79                 ps->items[++(ps->top)] = x;
  80 }
  81
  82 /****************************************************************************/
  83
  84 /*
  85  * stack_top -- Devuelve sin quitarlo de la pila el elemento que esta en el
  86  * top de la misma, si no est  vacia
  87  * Parametros:
  88  *      *ps: puntero a la pila
  89  * Devuelve:
  90  *      El elemento del top de la pila si no esta vacia
  91  *      si esta vacia devuelve NULL
  92  */
  93 element_type stack_top(struct stack_t *ps)
  94 {
  95         if (empty(ps))  return NULL;
  96         return(ps->items[ps->top]);
  97 }
  98
  99 /****************************************************************************/
 100
 101 /*
 102 stack_t::stack_t()
 103 {}
 104
 105 stack_t::~stack_t()
 106 {}
 107 */