added index attribute to field class

src/sql/field.cpp

@@ -3,21 +3,29 @@
 namespace matador::sql {
 
 field::field(std::string name)
-  : name_(std::move(name)), value_(nullptr), type_(field_traits<nullptr_t>::type())
+  : name_(std::move(name))
+  , value_(nullptr)
+  , type_(field_traits<nullptr_t>::type())
 {}
 
 field::field(field &&x) noexcept
-  : name_(std::move(x.name_)), value_(std::move(x.value_)), type_(x.type_)
+  : name_(std::move(x.name_))
+  , index_(x.index_)
+  , value_(std::move(x.value_))
+  , type_(x.type_)
 {
   x.value_ = nullptr;
+  x.index_ = -1;
   x.type_ = field_type::Null;
 }
 
 field &field::operator=(field &&x) noexcept
 {
   name_ = std::move(x.name_);
+  index_ = x.index_;
   value_ = std::move(x.value_);
   type_ = x.type_;
+  x.index_ = -1;
   x.value_ = nullptr;
   x.type_ = field_type::Null;
 
@@ -29,6 +37,11 @@ const std::string &field::name() const
   return name_;
 }
 
+int field::index() const
+{
+  return index_;
+}
+
 std::ostream &operator<<(std::ostream &out, const field &col)
 {
   out << col.str();