From 9d35ddb703d7ba22bdd6cdbaaf3b5c992ec79025 Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Fri, 24 Oct 2025 15:14:07 -0500
Subject: add list copy

---
 lichen.c      | 32 +++++++++++++++++++++++++-------
 lichen.h      |  6 +++---
 lichen.test.c | 29 +++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+), 10 deletions(-)

diff --git a/lichen.c b/lichen.c
index b0b0684..d7f0f82 100644
--- a/lichen.c
+++ b/lichen.c
@@ -77,10 +77,10 @@ void li_free_ll(struct li_ll_t *list, void (*free_data)(void*)) {
 }
 
 
-void li_ll_append(struct li_ll_t *list, void *data) {
+int li_ll_append(struct li_ll_t *list, void *data) {
   li_llnode_t *n = li_alloc_llnode();
   if (n == NULL) {
-    return;
+    return 1;
   }
   n->data = data;
   if (list->end != NULL) {
@@ -91,13 +91,14 @@ void li_ll_append(struct li_ll_t *list, void *data) {
     list->end = n;
   }
   list->count += 1;
+  return 0;
 }
 
 
-void li_ll_prepend(struct li_ll_t *list, void *data) {
+int li_ll_prepend(struct li_ll_t *list, void *data) {
   li_llnode_t *n = li_alloc_llnode();
   if (n == NULL) {
-    return;
+    return 1;
   }
   n->data = data;
   if (list->head != NULL) {
@@ -108,10 +109,27 @@ void li_ll_prepend(struct li_ll_t *list, void *data) {
     list->end = n;
   }
   list->count += 1;
+  return 0;
 }
 
 
-struct li_ll_t * li_copy_list(struct li_ll_t *list) {
-  list = list;
-  return NULL;
+int li_copy_list(struct li_ll_t **dst, struct li_ll_t *src, void *(*copy_data)(void*)) {
+  *dst = li_alloc_ll();
+  if (*dst == NULL) {
+    return 1;
+  }
+
+  (*dst)->tag = src->tag;
+
+  for (li_llnode_t *n = src->head; n != NULL; n = n->next) {
+    void *dup = copy_data(n->data);
+    if (dup == NULL) {
+      return 1;
+    }
+    if (li_ll_append(*dst, dup) != 0) {
+      return 1;
+    }
+  }
+
+  return 0;
 }
diff --git a/lichen.h b/lichen.h
index 4bcd608..5f13e85 100644
--- a/lichen.h
+++ b/lichen.h
@@ -49,9 +49,9 @@ typedef struct li_ll_t {
 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);
-void li_ll_prepend(struct li_ll_t *list, void *data);
-struct li_ll_t * li_copy_list(struct li_ll_t *list);
+int li_ll_append(struct li_ll_t *list, void *data);
+int li_ll_prepend(struct li_ll_t *list, void *data);
+int li_copy_list(struct li_ll_t **dst, struct li_ll_t *src, void *(*copy_data)(void*));
 
 
 
diff --git a/lichen.test.c b/lichen.test.c
index 622f480..946e0be 100644
--- a/lichen.test.c
+++ b/lichen.test.c
@@ -146,6 +146,35 @@ LILY_TEST("mix prepends and appends") {
 #include LILY_PUSH_TEST()
 
 
+void * copy_int(void *n) {
+  int *copy = malloc(sizeof(int));
+  *copy = *((int*)n);
+  return copy;
+}
+LILY_TEST("copy a list") {
+  struct li_ll_t *list_a = li_alloc_ll();
+  list_a->tag = 8;
+  int a = 1; int b = 2; int c = 3;
+  li_ll_append(list_a, &a);
+  li_ll_append(list_a, &b);
+  li_ll_append(list_a, &c);
+
+  struct li_ll_t *list_b;
+  li_copy_list(&list_b, list_a, copy_int);
+  li_free_ll(list_a, do_nothing);
+
+  REQUIRE_NEQ(list_b, NULL, "%p");
+  CHECK_EQ(list_b->tag, 8, "%d");
+  CHECK_EQ(list_b->count, 3, "%d");
+  CHECK_EQ(*((int*)list_b->head->data), a, "%d");
+  CHECK_EQ(*((int*)list_b->head->next->data), b, "%d");
+  CHECK_EQ(*((int*)list_b->head->next->next->data), c, "%d");
+
+  li_free_ll(list_b, free);
+}
+#include LILY_PUSH_TEST()
+
+
 
 #define LILY_FILE_END
 #include LILY_REGISTER_TESTS()
-- 
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