1 files changed, 45 insertions, 15 deletions

diff --git a/src/list.c b/src/list.c
index 29ddcf1..0573512 100644
--- a/src/list.c
+++ b/src/list.c
@@ -1,9 +1,21 @@
 #include "list.h"
 #include "util.h"
 
+void
+list_free(struct link *head, void (*free_item)(void *), int offset)
+{
+	struct link *item;
+
+	while (head->next) {
+		item = link_pop(head->next);
+		free_item(((void *) item) - offset);
+	}
+}
+
 int
 list_empty(struct link *head)
 {
+	ASSERT(head != NULL);
 	return head->next == NULL;
 }
 
@@ -28,20 +40,37 @@ list_ffind(struct link *head, struct link *link)
 	struct link *iter;
 
 	ASSERT(head != NULL);
-
 	for (iter = head->next; iter && iter != link; iter = iter->next);
-
 	return (iter == link);
 }
 
 struct link *
-link_back(struct link *link)
+list_at(struct link *head, int n)
 {
-	ASSERT(link != NULL);
+	ASSERT(head != NULL);
+	return link_iter(head->next, n);
+}
 
-	for (; link->next; link = link->next);
+void
+list_push_front(struct link *head, struct link *link)
+{
+	link_append(head, link);
+}
 
-	return link;
+void
+list_push_back(struct link *cur, struct link *link)
+{
+	struct link *back;
+
+	back = link_back(cur);
+	link_append(back, link);
+}
+
+struct link *
+list_pop_front(struct link *head)
+{
+	ASSERT(head != NULL);
+	return link_pop(head->next);
 }
 
 void
@@ -73,6 +102,16 @@ link_append(struct link *cur, struct link *link)
 }
 
 struct link *
+link_back(struct link *link)
+{
+	ASSERT(link != NULL);
+
+	for (; link->next; link = link->next);
+
+	return link;
+}
+
+struct link *
 link_pop(struct link *link)
 {
 	ASSERT(link != NULL);
@@ -97,12 +136,3 @@ link_iter(struct link *link, int n)
 
 	return link;
 }
-
-void
-list_push_back(struct link *cur, struct link *link)
-{
-	struct link *back;
-
-	back = link_back(cur);
-	link_append(back, link);
-}