reverse iterators

.gitignore

 .deps
 utf8_test
+
+json_unit

src/json.hpp.re2c

@@ -93,7 +93,10 @@ class basic_json
     using iterator = basic_json::iterator;
     /// a const iterator for a basic_json container
     using const_iterator = basic_json::const_iterator;
-
+    /// a reverse iterator for a basic_json container
+    using reverse_iterator = std::reverse_iterator<iterator>;
+    /// a const reverse iterator for a basic_json container
+    using const_reverse_iterator = std::reverse_iterator<const_iterator>;
 
     ///////////////////////////
     // JSON value data types //
@@ -264,6 +267,8 @@ class basic_json
               std::enable_if<
                   not std::is_same<V, basic_json::iterator>::value and
                   not std::is_same<V, basic_json::const_iterator>::value and
+                  not std::is_same<V, basic_json::reverse_iterator>::value and
+                  not std::is_same<V, basic_json::const_reverse_iterator>::value and
                   not std::is_same<V, typename array_t::iterator>::value and
                   not std::is_same<V, typename array_t::const_iterator>::value and
                   std::is_constructible<basic_json, typename V::value_type>::value, int>::type
@@ -822,6 +827,30 @@ class basic_json
         return result;
     }
 
+    /// returns a reverse iterator to the beginning
+    inline reverse_iterator rbegin() noexcept
+    {
+        return reverse_iterator(end());
+    }
+
+    /// returns a reverse iterator to the end
+    inline reverse_iterator rend() noexcept
+    {
+        return reverse_iterator(begin());
+    }
+
+    /// returns a reverse iterator to the beginning
+    inline const_reverse_iterator crbegin() const noexcept
+    {
+        return const_reverse_iterator(cend());
+    }
+
+    /// returns a reverse iterator to the end
+    inline const_reverse_iterator crend() const noexcept
+    {
+        return const_reverse_iterator(cbegin());
+    }
+
 
     //////////////
     // capacity //