fixed restriction and constraint class to use size_t

source/core/object/restriction.cpp

@@ -4,16 +4,23 @@
 #include "matador/object/object.hpp"
 
 namespace matador::object {
-restriction::restriction(const class attribute& attr)
-: attr_(attr) {}
+restriction::restriction(const size_t attr_index)
+: index_(attr_index) {}
 
-const class attribute& restriction::attribute() const {
-  return attr_;
+size_t restriction::attribute_index() const {
+  return index_;
 }
 
 std::string restriction::column_name() const {
-  return attr_.name();
+  const auto o = owner_.lock();
+  return o ? o->attributes().at(index_).name() : "";
 }
+
+utils::constraints restriction::options() const {
+  const auto o = owner_.lock();
+  return o ? o->attributes().at(index_).attributes().options() : utils::constraints::None;
+}
+
 std::shared_ptr<object> restriction::owner() const {
   return owner_.lock();
 }