1 files changed, 77 insertions, 0 deletions
diff --git a/src/queue.c b/src/queue.c
new file mode 100644
index 00000000..90823ae6
--- /dev/null
+++ b/src/queue.c
@@ -0,0 +1,77 @@
+#include <assert.h>
+#include <stdlib.h>
+
+#include "queue.h"
+
+struct queue_entry {
+    struct queue_entry *next;
+    void *data;
+};
+
+struct queue {
+    struct queue_entry *front, *back;
+    unsigned length;
+};
+
+struct queue* queue_new(void) {
+    struct queue *q = malloc(sizeof(struct queue));
+    assert(q);
+    q->front = q->back = NULL;
+    q->length = 0;
+    return q;
+}
+
+void queue_free(struct queue* q, void (*destroy)(void *p, void *userdata), void *userdata) {
+    struct queue_entry *e;
+    assert(q);
+
+    e = q->front;
+    while (e) {
+        struct queue_entry *n = e->next;
+
+        if (destroy)
+            destroy(e->data, userdata);
+
+        free(e);
+        e = n;
+    }
+
+    free(q);
+}
+
+void queue_push(struct queue *q, void *p) {
+    struct queue_entry *e;
+
+    e = malloc(sizeof(struct queue_entry));
+
+    e->data = p;
+    e->next = NULL;
+
+    if (q->back)
+        q->back->next = e;
+    else {
+        assert(!q->front);
+        q->front = e;
+    }
+
+    q->back = e;
+    q->length++;
+}
+
+void* queue_pop(struct queue *q) {
+    void *p;
+    struct queue_entry *e;
+    assert(q);
+
+    if (!(e = q->front))
+        return NULL;
+
+    q->front = e->next;
+    if (q->back == e)
+        q->back = NULL;
+
+    p = e->data;
+    free(e);
+
+    return p;
+}