Implements iterator for user data collection

src/Evaluator/Iterator/Iterator.hpp

@@ -10,7 +10,7 @@ using namespace std;
 namespace Porygon::Evaluation{
     class Iterator {
     public:
-        virtual EvalValue* GetCurrent() = 0;
+        virtual const  EvalValue* GetCurrent() = 0;
         virtual bool MoveNext() = 0;
         virtual void Reset() = 0;
         virtual ~Iterator(){}

src/Evaluator/Iterator/NumericalKeyIterator.hpp

@@ -16,7 +16,7 @@ namespace Porygon::Evaluation{
         explicit NumericalKeyIterator(const NumericalTableEvalValue* table)
                 : _vec(table->GetTable()), _size(_vec->size() + 1){}
 
-        inline EvalValue* GetCurrent() final{
+        inline const EvalValue* GetCurrent() final{
             return new IntegerEvalValue(_position);
         }
 

src/Evaluator/Iterator/SimpleKeyIterator.hpp

@@ -15,7 +15,7 @@ namespace Porygon::Evaluation{
         explicit TableKeyIterator(const TableEvalValue* table)
                 : _iterator(table->GetTableIterator()), _end(table->GetTableIteratorEnd()){}
 
-        inline EvalValue* GetCurrent() final{
+        inline const EvalValue* GetCurrent() final{
             return new StringEvalValue(*_iterator->first.GetString());
         }