gistfile1.txt

struct queue_node {
  struct queue_node *next;
  void *p;
};

struct vertex {
  /* ... */
  struct queue_node queue_entry;
};

struct queue {
  struct queue_node *head, *tail;
};

void queue_push(struct queue *q, struct queue_node *node);
struct queue_node *queue_pop(struct queue *q);