Make variant iterator bidirectional and stdlib compatible

src/variant.cpp

@@ -164,6 +164,33 @@ variant_iterator variant_iterator::operator++(int)
 	return iter;
 }
 
+variant_iterator& variant_iterator::operator--()
+{
+	if (type_ == TYPE_LIST)
+	{
+		--list_iterator_;
+	} else if (type_ == TYPE_MAP)
+	{
+		--map_iterator_;
+	}
+
+	return *this;
+}
+
+variant_iterator variant_iterator::operator--(int)
+{
+	variant_iterator iter(*this);
+	if (type_ == TYPE_LIST)
+	{
+		--list_iterator_;
+	} else if (type_ == TYPE_MAP)
+	{
+		--map_iterator_;
+	}
+
+	return iter;
+}
+
 variant_iterator& variant_iterator::operator=(const variant_iterator& that)
 {
 	if (this == &that)

src/variant.hpp

@@ -181,6 +181,12 @@ class variant {
  */
 class variant_iterator {
 public:
+	typedef variant value_type;
+	typedef std::bidirectional_iterator_tag iterator_category;
+	typedef variant& reference;
+	typedef variant* pointer;
+	typedef int difference_type;
+
 	/**
 	 * Constructor for a TYPE_NULL variant.
 	 */
@@ -209,6 +215,8 @@ class variant_iterator {
 	variant operator*() const;
 	variant_iterator& operator++();
 	variant_iterator operator++(int);
+	variant_iterator& operator--();
+	variant_iterator operator--(int);
 	variant_iterator& operator=(const variant_iterator& that);
 	bool operator==(const variant_iterator& that) const;
 	bool operator!=(const variant_iterator& that) const;