add list prepend

1 files changed, 19 insertions, 3 deletions

diff --git a/lichen.c b/lichen.c
index f028d92..b0b0684 100644
--- a/lichen.c
+++ b/lichen.c
@@ -79,10 +79,10 @@ void li_free_ll(struct li_ll_t *list, void (*free_data)(void*)) {
 
 void li_ll_append(struct li_ll_t *list, void *data) {
   li_llnode_t *n = li_alloc_llnode();
-  n->data = data;
   if (n == NULL) {
     return;
   }
+  n->data = data;
   if (list->end != NULL) {
     list->end->next = n;
     list->end = n;
@@ -93,9 +93,25 @@ void li_ll_append(struct li_ll_t *list, void *data) {
   list->count += 1;
 }
 
+
+void li_ll_prepend(struct li_ll_t *list, void *data) {
+  li_llnode_t *n = li_alloc_llnode();
+  if (n == NULL) {
+    return;
+  }
+  n->data = data;
+  if (list->head != NULL) {
+    n->next = list->head;
+    list->head = n;
+  } else {
+    list->head = n;
+    list->end = n;
+  }
+  list->count += 1;
+}
+
+
 struct li_ll_t * li_copy_list(struct li_ll_t *list) {
   list = list;
   return NULL;
 }
-
-