1 files changed, 115 insertions, 0 deletions

diff --git a/src/queue.c b/src/queue.c
new file mode 100644
index 0000000..6a472ee
--- /dev/null
+++ b/src/queue.c
@@ -0,0 +1,115 @@
+/* Standard C */
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/* Project */
+#include "util.h"
+
+/* --8<-- queue_type */
+typedef int T;
+
+struct queue_item {
+        struct queue_item *next;
+        T                  data;
+};
+
+struct queue {
+        struct queue_item *head, *tail;
+};
+/* -->8-- */
+
+/* --8<-- queue_init */
+void
+queue_init(struct queue *queue)
+{
+        queue->head = NULL;
+}
+/* -->8-- */
+
+/* --8<-- queue_put */
+void
+queue_put(struct queue *queue, T data)
+{
+        struct queue_item *new_item;
+
+        if ( (new_item = malloc(sizeof *new_item)) != NULL ) {
+                struct queue_item *tmp = queue->tail;
+                new_item->data         = data;
+                new_item->next         = NULL;
+                queue->tail            = new_item;
+                if ( queue->head == NULL )
+                        queue->head = queue->tail;
+                else
+                        tmp->next = queue->tail;
+        }
+        else {
+                ERROR("out of memory");
+        }
+}
+/* -->8-- */
+
+/* --8<-- queue_get */
+bool
+queue_get(struct queue *queue, T *data)
+{
+        if ( queue->head ) {
+                struct queue_item *next = queue->head->next;
+
+                if ( data ) {
+                        *data = queue->head->data;
+                }
+                free(queue->head);
+                queue->head = next;
+
+                return true;
+        }
+        else
+                return false;
+}
+/* -->8-- */
+
+/* --8<-- queue_empty */
+bool
+queue_empty(struct queue *queue)
+{
+        return queue->head == NULL;
+}
+/* -->8-- */
+
+/* --8<-- queue_free */
+void
+queue_free(struct queue *queue)
+{
+        struct queue_item *item, *next;
+
+        for ( item = queue->head; item; item = next ) {
+                next = item->next;
+                free(item);
+        }
+}
+/* -->8-- */
+
+int
+main()
+{
+        struct queue queue[1];
+
+        queue_init(queue);
+
+        for ( int i = 0; i != 10; ++i ) {
+                queue_put(queue, i);
+        }
+
+        while ( !queue_empty(queue) ) {
+                int i;
+                if ( queue_get(queue, &i) )
+                        printf("%d\n", i);
+                else
+                        ERROR("this shouldn't happen!");
+        }
+
+        queue_free(queue);
+
+        return EXIT_SUCCESS;
+}