View source for ADTs de 1ª ordem: Fila

== Interface ==

  #ifndef __QUEUE_H__
  #define __QUEUE_H__
  
  #include "Item.h"
  
  typedef struct queue *Q;
  
  Q    QUEUEinit(int);
  int  QUEUEempty(Q);
  void QUEUEput(Q, Item);
  Item QUEUEget(Q);
  
  #endif

== Implementação ==

=== Implementação baseada em lista ===

  #include <stdlib.h>
  #include "Item.h"
  #include "QUEUE.h"
  
  typedef struct QUEUEnode* link;
  struct QUEUEnode { Item item; link next; };
  struct queue     { link head; link tail; };
  
  link NEW(Item item, link next) {
    link x = malloc(sizeof *x);
    x->item = item; x->next = next;     
    return x;                         
  }                                   
  
  Q QUEUEinit(int maxN) {
    Q q = malloc(sizeof *q); 
    q->head = NULL;
    q->tail = NULL; 
    return q;
  }
  
  int QUEUEempty(Q q) { return q->head == NULL; }
  
  void QUEUEput(Q q, Item item) { 
    if (q->head == NULL) {
      q->tail = NEW(item, q->head);
      q->head = q->tail;
      return;
    }
  
    q->tail->next = NEW(item, q->tail->next); 
    q->tail       = q->tail->next;
  }
  
  Item QUEUEget(Q q) {
    Item item = q->head->item;
    link t    = q->head->next;
    free(q->head);
    q->head = t;
    return item;
  }

== Cliente ==

  #include <stdio.h>
  #include <stdlib.h>
  
  #include "Item.h"  /* também incluÃdo por QUEUE.h */
  #include "QUEUE.h"
  #define M 10
  
  main(int argc, char *argv[]) {
    int i, j, N = atoi(argv[1]); 
    Q queues[M]; 
  
    for (i = 0; i < M; i++) queues[i] = QUEUEinit(N);
    for (i = 0; i < N; i++) QUEUEput(queues[rand() % M], i);
  
    for (i = 0; i < M; i++, printf("\n"))
      for (j = 0; !QUEUEempty(queues[i]); j++) 
        printf("%3d ", QUEUEget(queues[i]));
  }