Implement List::copy

Sources/Objectively/List.c

@@ -32,6 +32,26 @@
 
 #pragma mark - Object
 
+/**
+ * @see Object::copy(const Object *)
+ * @remarks Elements are not retained, since List does not retain them on
+ * insertion either. The copy does not inherit `destroy`, and so borrows the
+ * elements rather than owning them, as `filteredList` and `mappedList` do.
+ */
+static Object *copy(const Object *self) {
+
+  const List *this = (List *) self;
+
+  List *copy = $(alloc(List), init);
+  assert(copy);
+
+  for (ListNode *node = this->head; node; node = node->next) {
+    $(copy, append, node->element);
+  }
+
+  return (Object *) copy;
+}
+
 /**
  * @see Object::dealloc(Object *)
  */
@@ -357,6 +377,7 @@ static void _sort(List *self, Comparator comparator) {
  */
 static void initialize(Class *clazz) {
 
+  ((ObjectInterface *) clazz->interface)->copy = copy;
   ((ObjectInterface *) clazz->interface)->dealloc = dealloc;
 
   ((ListInterface *) clazz->interface)->append = append;

Tests/Objectively/List.c

@@ -25,6 +25,46 @@
 
 #include "Objectively.h"
 
+START_TEST(copyList) {
+
+  int one = 1, two = 2, three = 3, four = 4;
+
+  List *list = $(alloc(List), init);
+
+  $(list, append, &one);
+  $(list, append, &two);
+  $(list, append, &three);
+
+  List *copy = (List *) $((Object *) list, copy);
+
+  ck_assert_ptr_ne(list, copy);
+  ck_assert_int_eq(3, copy->count);
+
+  ListNode *a = list->head, *b = copy->head;
+  while (a && b) {
+    ck_assert_ptr_eq(a->element, b->element);
+    ck_assert_ptr_ne(a, b);
+    a = a->next;
+    b = b->next;
+  }
+  ck_assert_ptr_eq(NULL, a);
+  ck_assert_ptr_eq(NULL, b);
+
+  $(copy, append, &four);
+
+  ck_assert_int_eq(4, copy->count);
+  ck_assert_int_eq(3, list->count);
+
+  release(copy);
+
+  ck_assert_int_eq(3, list->count);
+  ck_assert_ptr_eq(&one, list->head->element);
+  ck_assert_ptr_eq(&three, list->tail->element);
+
+  release(list);
+
+} END_TEST
+
 START_TEST(appendElement) {
 
   int one = 1, two = 2, three = 3;
@@ -384,6 +424,7 @@ int main(int argc, char **argv) {
   TCase *tcase = tcase_create("List");
   tcase_add_test(tcase, appendElement);
   tcase_add_test(tcase, containsElement);
+  tcase_add_test(tcase, copyList);
   tcase_add_test(tcase, enumerate);
   tcase_add_test(tcase, filter);
   tcase_add_test(tcase, filteredList);