lang: struct CryQueue supports lookups for nth and rear elements in list.

src/structures/queue.h

@@ -28,6 +28,9 @@ void            	cry_queue_free(struct CryQueue* queue, cry_free_funptr handler)
 int             	cry_queue_size(struct CryQueue* queue);
 
 pointer         	cry_queue_front(struct CryQueue* queue);
+pointer                 cry_queue_rear(struct CryQueue* queue);
+pointer                 cry_queue_nth(struct CryQueue* queue, size_t index);
+
 pointer         	cry_queue_dequeue(struct CryQueue* queue);
 void            	cry_queue_enqueue(struct CryQueue* queue, pointer data);
 

src/structures/single_linked_list.c

@@ -9,7 +9,7 @@
  * Crystal is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * Lesser GNU General Public License for more details.
+ * Lesser GNU General Public License for more derears.
  *
  * You should have received a copy of the Lesser GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
@@ -31,19 +31,19 @@ struct Stack {
 	struct Node* begin;
 };
 
-struct Queue {
+struct CryQueue {
 	struct Node* front;
-	struct Node* tail;
+	struct Node* rear;
 };
 
 
 struct CryQueue*  	
 cry_queue_new(void)
 {
-	struct Queue* list = cry_malloc(struct Queue);
+	struct CryQueue* list = cry_malloc(struct CryQueue);
 	list->front = 0;
-	list->tail = 0;
-	return cry_cast(struct CryQueue*, list);
+	list->rear = 0;
+	return list;
 }
 
 
@@ -52,7 +52,7 @@ cry_queue_free(struct CryQueue* queue, cry_free_funptr handler)
 {
 	assert(queue != 0);
 
-	struct Node* node = cry_cast(struct Queue*, queue)->front;
+	struct Node* node = queue->front;
 	struct Node* tmp = 0;
 
 	while(node != 0) {
@@ -76,7 +76,7 @@ cry_queue_size(struct CryQueue* queue)
 	assert(queue != 0);
 
 	size_t length = 0;
-	struct Node* node = cry_cast(struct Queue*, queue)->front;
+	struct Node* node = queue->front;
 
 	while(node != 0) {
 		node = node->next;
@@ -92,10 +92,36 @@ cry_queue_front(struct CryQueue* queue)
 {
 	assert(queue != 0);
 
-	if(cry_cast(struct Queue*, queue)->front == 0)
+	if(queue->front == 0)
 		return 0;
 	else
-		return cry_cast(struct Queue*, queue)->front->data;
+		return queue->front->data;
+}
+
+
+pointer
+cry_queue_rear(struct CryQueue* queue)
+{
+	assert(queue != 0);
+
+	if(queue->rear == 0)
+		return 0;
+	else
+		return queue->rear->data;
+}
+
+
+pointer
+cry_queue_nth(struct CryQueue* queue, size_t index)
+{
+	assert(queue != 0);
+
+	struct Node* node = queue->front;
+
+	while(node != 0 && index-- > 0)
+		node = node->next;
+
+	return node;
 }
 
 
@@ -104,8 +130,7 @@ cry_queue_dequeue(struct CryQueue* queue)
 {
 	assert(queue != 0);
 
-	struct Queue* list = cry_cast(struct Queue*, queue);
-	struct Node* front = list->front;
+	struct Node* front = queue->front;
 	pointer data = 0;
 
 	if(front == 0) 
@@ -113,10 +138,10 @@ cry_queue_dequeue(struct CryQueue* queue)
 
 	data = front->data;
 
-	if(list->front == list->tail) 
-		list->front = list->tail = 0;
+	if(queue->front == queue->rear) 
+		queue->front = queue->rear = 0;
 	else
-		list->front = front->next;
+		queue->front = front->next;
 
 	cry_free(front);
 
@@ -129,18 +154,17 @@ cry_queue_enqueue(struct CryQueue* queue, pointer data)
 {
 	assert(queue != 0);
 
-	struct Queue* list = cry_cast(struct Queue*, queue);
 	struct Node* node = cry_malloc(struct Node);
 
 	node->next = 0;
 	node->data = data;
 
-	if(list->front == 0) {
-		list->front = node;
-		list->tail = node;
+	if(queue->front == 0) {
+		queue->front = node;
+		queue->rear = node;
 	 } else {
-		list->tail->next = node;
-		list->tail = node;
+		queue->rear->next = node;
+		queue->rear = node;
 	}
 }