1 files changed, 35 insertions, 21 deletions

diff --git a/include/api-test/freelist.hpp b/include/api-test/freelist.hpp
index 3d0324d..cbcd56d 100644
--- a/include/api-test/freelist.hpp
+++ b/include/api-test/freelist.hpp
@@ -15,17 +15,20 @@ class freelist {
     }
 
     handle<T> add(const T& item) {
-        auto id = elements[0U].next_free;
+        // auto id = elements[0U].next_free;
+        auto id = next_free_id;
 
-        if (id == invalid_id) {
+        if (id == freelist<T>::invalid_id) {
             grow(elements.size());
 
-            id = elements[0U].next_free;
+            // id = elements[0U].next_free;
+            id = next_free_id;
         }
 
         auto& element = elements[id];
 
-        elements[0U].next_free = element.next_free;
+        next_free_id = element.next_free;
+        // elements[0U].next_free = element.next_free;
         element.item = std::move(item);
 
         return { id, ++element.generation };
@@ -33,8 +36,10 @@ class freelist {
 
     void remove(handle<T> handle) {
         assert(handle.generation == elements[handle.id].generation);
-        elements[handle.id].next_free = elements[0U].next_free;
-        elements[0U].next_free = handle.id;
+        // elements[handle.id].next_free = elements[0U].next_free;
+        // elements[0U].next_free = handle.id;
+        elements[handle.id].next_free = next_free_id;
+        next_free_id = handle.id;
     }
 
     T& operator[](handle<T> handle) {
@@ -47,12 +52,13 @@ class freelist {
         return elements[handle.id].item;
     }
 
-    static constexpr uint32_t invalid_id = -1;
+    static constexpr uint32_t invalid_id = UINT32_MAX;
 
 private:
     void grow(size_t grow_size) {
         auto size = elements.size();
-        uint32_t next_free = size;
+        uint32_t next_free = static_cast<uint32_t>(size);
+        next_free_id = next_free;
 
         elements.reserve(size + grow_size);
 
@@ -64,18 +70,19 @@ private:
             );
         }
 
-        elements.back().next_free = -1U;
+        elements.back().next_free = freelist<T>::invalid_id;
     }
 
     struct element {
         union {
             T item;
-            uint32_t next_free = -1;
+            uint32_t next_free = freelist<T>::invalid_id;
         };
         uint32_t generation = 0U;
     };
 
     std::vector<element>        elements;
+    uint32_t next_free_id;
 };
 
 template<const size_t initial_size = default_element_count>
@@ -87,51 +94,58 @@ class idlist {
     }
 
     handle<void> add() {
-        auto id = elements[0U].next_free;
+        // auto id = elements[0U].next_free;
+        auto id = next_free_id;
 
-        if (id == invalid_id) {
+        if (id == idlist<T>::invalid_id) {
             grow(elements.size());
 
-            id = elements[0U].next_free;
+            // id = elements[0U].next_free;
+            id = next_free_id;
         }
 
         auto& element = elements[id];
+        next_free_id = element.next_free;
         elements[0U].next_free = element.next_free;
-        element.next_free = -1;
+        element.next_free = idlist<T>::invalid_id;
 
         return { id, ++element.generation };
     }
 
     void remove(handle<void> handle) {
         assert(handle.generation == elements[handle.id].generation);
-        elements[handle.id].next_free = elements[0U].next_free;
-        elements[0U].next_free = handle.id;
+        // elements[handle.id].next_free = elements[0U].next_free;
+        // elements[0U].next_free = handle.id;
+        elements[handle.id].next_free = next_free_id;
+        next_free_id = handle.id;
     }
 
-    static constexpr uint32_t invalid_id = -1;
+    static constexpr uint32_t invalid_id = UINT32_MAX;
 
 private:
     void grow(size_t grow_size) {
         auto size = elements.size();
-        uint32_t next_free = size;
+        uint32_t next_free = static_cast<uint32_t>(size);
+        next_free_id = next_free;
 
         elements.reserve(size + grow_size);
 
         for (auto id { 0U }; id < initial_size; id++) {
             elements.push_back(
                 {
-                    .next_free = static_cast<uint32_t>(++next_free % initial_size),
+                    .next_free = static_cast<uint32_t>(++next_free% initial_size),
                 }
             );
         }
 
-        elements.back().next_free = -1U;
+        elements.back().next_free = idlist<T>::invalid_id;
     }
 
     struct element {
-        uint32_t next_free = -1;
+        uint32_t next_free = idlist<T>::invalid_id;
         uint32_t generation = 0U;
     };
 
     std::vector<element>        elements;
+    uint32_t next_free_id;
 };