From 24fbfb8c41c62b11506668a22074379115f57600 Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Fri, 24 Oct 2025 13:32:54 -0500
Subject: implement basic linked list append

---
 lichen.c      | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 lichen.h      |  9 +++++++++
 lichen.test.c | 30 ++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+)

diff --git a/lichen.c b/lichen.c
index e8c8e19..f028d92 100644
--- a/lichen.c
+++ b/lichen.c
@@ -49,6 +49,53 @@ li_llnode_t * li_copy_llnode(li_llnode_t *n) {
 void li_free_llnode(li_llnode_t *n, void (*free_data)(void*)) {
   if (n != NULL) {
     free_data(n->data);
+    li_free_llnode(n->next, free_data);
   }
   free(n);
 }
+
+
+struct li_ll_t * li_alloc_ll() {
+  struct li_ll_t *list = malloc(sizeof(struct li_ll_t));
+  if (list == NULL) {
+    fprintf(stderr, "failed to allocate linked list\n");
+    return NULL;
+  }
+
+  list->tag = 0;
+  list->count = 0;
+  list->head = NULL;
+  list->end = NULL;
+  return list;
+}
+
+void li_free_ll(struct li_ll_t *list, void (*free_data)(void*)) {
+  if (list != NULL) {
+    li_free_llnode(list->head, free_data);
+  }
+  free(list);
+}
+
+
+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;
+  }
+  if (list->end != NULL) {
+    list->end->next = n;
+    list->end = 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;
+}
+
+
diff --git a/lichen.h b/lichen.h
index b30c8cb..a607d24 100644
--- a/lichen.h
+++ b/lichen.h
@@ -41,9 +41,18 @@ typedef struct li_ll_t {
   int tag;
   size_t count;
   li_llnode_t *head;
+  li_llnode_t *end;
 } li_ll_t;
 
 
+// allocate a linked list
+struct li_ll_t * li_alloc_ll();
+// free a linked list
+void li_free_ll(struct li_ll_t *list, void (*free_data)(void*));
+void li_ll_append(struct li_ll_t *list, void *data);
+struct li_ll_t * li_copy_list(struct li_ll_t *list);
+
+
 
 
 #endif
diff --git a/lichen.test.c b/lichen.test.c
index 68d26d0..bca7d27 100644
--- a/lichen.test.c
+++ b/lichen.test.c
@@ -51,6 +51,36 @@ LILY_TEST("allocate, copy, and destroy llnode") {
 #include LILY_PUSH_TEST()
 
 
+
+LILY_TEST("append to list") {
+  struct li_ll_t *list = li_alloc_ll();
+  REQUIRE_NEQ(list, NULL, "%p");
+
+  int a = 1; int b = 2; int c = 3;
+
+  li_ll_append(list, &a);
+  CHECK_EQ(list->count, 1, "%d");
+  REQUIRE_NEQ(list->head, NULL, "%p");
+  CHECK_EQ(list->head->data, &a, "%p");
+  CHECK_EQ(list->head->next, NULL, "%p");
+
+  li_ll_append(list, &b);
+  CHECK_EQ(list->count, 2, "%d");
+  REQUIRE_NEQ(list->head->next, NULL, "%p");
+  CHECK_EQ(list->head->next->data, &b, "%p");
+  CHECK_EQ(list->head->next->next, NULL, "%p");
+
+  li_ll_append(list, &c);
+  CHECK_EQ(list->count, 3, "%d");
+  REQUIRE_NEQ(list->head->next->next, NULL, "%p");
+  CHECK_EQ(list->head->next->next->data, &c, "%p");
+  CHECK_EQ(list->head->next->next->next, NULL, "%p");
+
+  li_free_ll(list, do_nothing);
+}
+#include LILY_PUSH_TEST()
+
+
 #define LILY_FILE_END
 #include LILY_REGISTER_TESTS()
 
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