iterator: use index_type for the indices pseudo-container

iterator.hpp

@@ -251,14 +251,17 @@ namespace util {
     template <typename ContainerT>
     class indices {
     public:
+        using value_type = typename index_type<ContainerT>::type;
+
         indices (const ContainerT &_container):
             m_container (_container)
         { ; }
 
-        class iterator : public std::iterator<std::forward_iterator_tag, std::size_t, std::size_t> {
+        class iterator {
         public:
+            using iterator_category = std::forward_iterator_tag;
 
-            iterator (std::size_t _index):
+            iterator (value_type _index):
                 m_index (_index)
             { ; }
 
@@ -281,18 +284,18 @@ namespace util {
                 return *this;
             };
 
-            const std::size_t&
+            const value_type&
             operator* (void) const&
             {
                 return m_index;
             }
 
         private:
-            std::size_t m_index;
+            value_type m_index;
         };
 
-        iterator begin (void) const { return iterator { 0 }; }
+        iterator begin (void) const { return iterator { value_type {0} }; }
-        iterator end   (void) const { return iterator { m_container.size () }; }
+        iterator end   (void) const { return iterator { value_type (m_container.size ()) }; }
 
     private:
         const ContainerT &m_container;