initialize eval_set to a proper copy of involved_set

src/backends/packrat.c

@@ -103,7 +103,7 @@ HParseResult* grow(HParserCacheKey *k, HParseState *state, HRecursionHead *head)
   HParseResult *old_res = old_cached->right->result;
   
   // reset the eval_set of the head of the recursion at each beginning of growth
-  head->eval_set = head->involved_set;  // BUG: this must be a copy
+  head->eval_set = h_slist_copy(head->involved_set);
   HParseResult *tmp_res = perform_lowlevel_parse(state, k->parser);
 
   if (tmp_res) {

src/datastructures.c

@@ -41,6 +41,26 @@ HSlist* h_slist_new(HArena *arena) {
   return ret;
 }
 
+HSlist* h_slist_copy(HSlist *slist) {
+  HSlist *ret = h_slist_new(slist->arena);
+  HSlistNode *head = slist->head;
+  HSlistNode *tail;
+  if (head != NULL) {
+    h_slist_push(ret, head->elem);
+    tail = ret->head;
+    head = head->next;
+  }
+  while (head != NULL) {
+    // append head item to tail in a new node
+    HSlistNode *node = h_arena_malloc(slist->arena, sizeof(HSlistNode));
+    node->elem = head->elem;
+    node->next = NULL;
+    tail = tail->next = node;
+    head = head->next;
+  }
+  return ret;
+}
+
 void* h_slist_pop(HSlist *slist) {
   HSlistNode *head = slist->head;
   if (!head)

src/internal.h

@@ -209,6 +209,7 @@ HCountedArray *h_carray_new(HArena * arena);
 void h_carray_append(HCountedArray *array, void* item);
 
 HSlist* h_slist_new(HArena *arena);
+HSlist* h_slist_copy(HSlist *slist);
 void* h_slist_pop(HSlist *slist);
 void h_slist_push(HSlist *slist, void* item);
 bool h_slist_find(HSlist *slist, const void* item);