using std::variant instead of pointer

row.h

@@ -4,6 +4,7 @@
 #include "parser.h"
 #include "settings.h"
 
+#include <variant>
 #include <vector>
 
 namespace usql {
@@ -119,6 +120,8 @@ namespace usql {
         bool m_bool;
     };
 
+
+
     class Row {
 
     public:
@@ -139,14 +142,32 @@ namespace usql {
 	void setColumnValue(ColDefNode *col_def, ColValue &col_value);
 	void setColumnValue(ColDefNode *col_def, ValueNode *col_value);
 
-	ColValue &operator[](int i) const { return *m_columns[i]; }
+	ColValue &operator[](int i) const { 
+		auto type_index = m_columns[i].index(); 
+		switch (type_index) {
+			case 0:
+				return (ColValue &) *std::get_if<ColNullValue>(&m_columns[i]);
+			case 1:
+				return (ColValue &) *std::get_if<ColIntegerValue>(&m_columns[i]);
+			case 2:
+				return (ColValue &) *std::get_if<ColDoubleValue>(&m_columns[i]);
+			case 3:
+				return (ColValue &) *std::get_if<ColStringValue>(&m_columns[i]);
+			case 4:
+				return (ColValue &) *std::get_if<ColDateValue>(&m_columns[i]);
+			case 5:
+				return (ColValue &) *std::get_if<ColBooleanValue>(&m_columns[i]);
+		}
+		throw Exception("should not happen");	
+	}
 
 	int compare(const Row  &other) const;
 
 	void print(const std::vector<ColDefNode> &col_defs);
 	static int print_get_column_size(const ColDefNode &col_def);
     private:
-	std::vector<std::unique_ptr<ColValue>> m_columns;
+	// xx std::vector<std::unique_ptr<ColValue>> m_columns;
+	std::vector<std::variant<ColNullValue, ColIntegerValue, ColDoubleValue, ColStringValue, ColDateValue, ColBooleanValue>> m_columns;
     };
 
 }	// namespace