1 files changed, 8 insertions, 1 deletions
diff --git a/impl/IdSet.hpp b/impl/IdSet.hpp
index 2ba88d3..f845325 100644
--- a/impl/IdSet.hpp
+++ b/impl/IdSet.hpp
@@ -45,6 +45,12 @@ class IdSet {
     return *this;
   }
 
+  void invert() {
+    for (unsigned int i = 0; i < DIV_ROUND_UP(_length, CELL_SIZE); ++i) {
+      _values[i] = ~_values[i];
+    }
+  }
+
   bool contains(const T& obj) const {
     unsigned int id = obj.id();
     if (id >= _length) {
@@ -125,7 +131,8 @@ class IdSet {
       do {
         index++;
         for (;; index += CELL_SIZE) {
-          if (index == set._length) {
+          if (index >= set._length) {
+            index = set._length;
             return *this;
           }
           cell = index / CELL_SIZE;