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/*Queue implementation*/
typedef struct queue_element queue_element;
struct queue_element {
void *val;
struct queue_element *next;
};
typedef struct {
queue_element *first;
queue_element *last;
int size;
} queue;
typedef struct {
queue_element *prev;
queue_element *cur;
} queue_iterator;
queue_iterator* queue_iterator_new(queue *q) {
queue_iterator *it = malloc(sizeof(queue_iterator));
it->prev = NULL;
it->cur = q->first;
return it;
}
void queue_iterator_next(queue_iterator *it) {
it->prev = it->cur;
if (it->cur != NULL) {
it->cur = it->cur->next;
}
}
char queue_iterator_end(queue_iterator *it) {
return it->cur == NULL;
}
void queue_iterator_destroy(queue_iterator *it) {
free(it);
}
queue* queue_new() {
queue *q = malloc(sizeof(queue));
q->first = q->last = NULL;
q->size = 0;
return q;
}
void queue_push(queue *q, void *val) {
queue_element *q_e = malloc(sizeof(queue_element));
q_e->val = val;
q_e->next = NULL;
if (q->first == NULL) {
q->first = q->last = q_e;
}
else {
q->last = q->last->next = q_e;
}
q->size++;
}
void* queue_shift(queue *q) {
if (q->first == NULL) {
return NULL;
}
queue_element *q_e = q->first;
void *val = q_e->val;
q->first = q_e->next;
free(q_e);
q->size--;
return val;
}
void* queue_at(queue *q, queue_iterator *it) {
if (it->cur == NULL)
return NULL;
return it->cur->val;
}
void queue_del(queue *q, queue_iterator *it) {
if (it->cur == NULL)
return;
if (it->prev != NULL) {
it->prev->next = it->cur->next;
}
else {
q->first = it->cur->next;
}
if (q->last == it->cur)
q->last = it->prev;
queue_element *cur = it->cur;
it->cur = it->cur->next;
free(cur);
q->size--;
}
void queue_clear(queue *q) {
queue_element *q_e, *old;
for (q_e = q->first; q_e != NULL; old = q_e, q_e = q_e->next, free(old));
q->first = q->last = NULL;
q->size = 0;
}
int queue_size(queue *q) {
return q->size;
}
void queue_destroy(queue *q) {
queue_element *q_e, *old;
for (q_e = q->first; q_e != NULL; old = q_e, q_e = q_e->next, free(old));
free(q);
}
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