removed name member from restriction and changed attribute member to a reference

source/core/object/restriction.cpp

@@ -4,32 +4,16 @@
 #include "matador/object/object.hpp"
 
 namespace matador::object {
-restriction::restriction(std::string name)
-: name_(std::move(name)) {}
+restriction::restriction(const class attribute& attr)
+: attr_(attr) {}
 
-std::string restriction::name() const {
-  return type_string() + name_;
-}
-
-const class attribute* restriction::attribute() const {
-  if (std::holds_alternative<class attribute*>(attr_)) {
-    return std::get<class attribute*>(attr_);
-  }
-
-  return nullptr;
+const class attribute& restriction::attribute() const {
+  return attr_;
 }
 
 std::string restriction::column_name() const {
-    if (std::holds_alternative<class attribute*>(attr_)) {
-        return std::get<class attribute*>(attr_)->name();
-    }
-    if (std::holds_alternative<std::string>(attr_)) {
-        return std::get<std::string>(attr_);
-    }
-
-    return "";
+  return attr_.name();
 }
-
 std::shared_ptr<object> restriction::owner() const {
   return owner_;
 }