#include "queue.h"
#include <stdlib.h>

struct Queuerep
{ void* data;
  Queue next;
};

Queue createq(void)
{ return 0;
}

Queue enqueue(Queue q, void* elem)
{ Queue temp = malloc(sizeof(struct Queuerep));
  temp->data = elem;
  if (q)
  { temp->next = q->next;
    q->next = temp;
    q = temp;
  }
  else
  { q = temp;
    q->next = temp;
  }
  return q;
}

void* frontq(Queue q)
{ return q->next->data;
}

Queue dequeue(Queue q)
{ Queue temp;
  if (q == q->next)
  { temp = q;
    q = 0;
  }
  else
  { temp = q->next;
    q->next = q->next->next;
  }
  free(temp);  
  return q;
}

int emptyq(Queue q)
{ return q == 0;
}