Fix reverse_iterator in Vector and tests (#5344)

Before this commit tests for iterators passed, even if the code inside
the loop has not been executed.

1 files changed, 12 insertions, 10 deletions

diff --git a/include/flatbuffers/flatbuffers.h b/include/flatbuffers/flatbuffers.h
index a1a95f00..83dd09de 100644
--- a/include/flatbuffers/flatbuffers.h
+++ b/include/flatbuffers/flatbuffers.h
@@ -201,14 +201,16 @@ template<typename T, typename IT> struct VectorIterator {
 template<typename Iterator> struct VectorReverseIterator :
   public std::reverse_iterator<Iterator> {
 
-  explicit VectorReverseIterator(Iterator iter) : iter_(iter) {}
+  explicit VectorReverseIterator(Iterator iter) :
+    std::reverse_iterator<Iterator>(iter) {}
 
-  typename Iterator::value_type operator*() const { return *(iter_ - 1); }
-
-  typename Iterator::value_type operator->() const { return *(iter_ - 1); }
+  typename Iterator::value_type operator*() const {
+    return *(std::reverse_iterator<Iterator>::current);
+  }
 
- private:
-  Iterator iter_;
+  typename Iterator::value_type operator->() const {
+    return *(std::reverse_iterator<Iterator>::current);
+  }
 };
 
 struct String;
@@ -269,11 +271,11 @@ template<typename T> class Vector {
   iterator end() { return iterator(Data(), size()); }
   const_iterator end() const { return const_iterator(Data(), size()); }
 
-  reverse_iterator rbegin() { return reverse_iterator(end()); }
-  const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); }
+  reverse_iterator rbegin() { return reverse_iterator(end() - 1); }
+  const_reverse_iterator rbegin() const { return const_reverse_iterator(end() - 1); }
 
-  reverse_iterator rend() { return reverse_iterator(end()); }
-  const_reverse_iterator rend() const { return const_reverse_iterator(end()); }
+  reverse_iterator rend() { return reverse_iterator(begin() - 1); }
+  const_reverse_iterator rend() const { return const_reverse_iterator(begin() - 1); }
 
   const_iterator cbegin() const { return begin(); }