order by refactoring

row.h

@@ -11,16 +11,24 @@ namespace usql {
     struct ColValue {
 
 	virtual bool isNull() { return false; };
-	virtual long getIntValue() { throw Exception("Not supported"); };
-	virtual double getDoubleValue() { throw Exception("Not supported"); };
-	virtual std::string getStringValue() { throw Exception("Not supported"); };
+	virtual long getIntValue() = 0;
+	virtual double getDoubleValue() = 0;
+	virtual std::string getStringValue() = 0;
+
+	virtual int compare(ColValue * other) = 0;
+
+	virtual ~ColValue() = default;
     };
 
 
     struct ColNullValue : ColValue {
 
-	virtual bool isNull() { return true; };
-	virtual std::string getStringValue() { return "null"; };
+        bool isNull() override { return true; };
+	long getIntValue() override { throw Exception("Not supported"); };
+	double getDoubleValue() override { throw Exception("Not supported"); };
+	std::string getStringValue() override { return "null"; };
+
+	int compare(ColValue * other) override;
     };
 
 
@@ -29,11 +37,13 @@ namespace usql {
 	ColIntegerValue(long value) : m_integer(value) {};
 	ColIntegerValue(const ColIntegerValue &other) : m_integer(other.m_integer) {};
 
-	virtual long getIntValue() { return m_integer; };
-	virtual double getDoubleValue() { return (double) m_integer; };
-	virtual std::string getStringValue() { return std::to_string(m_integer); };
+	long getIntValue() override { return m_integer; };
+	double getDoubleValue() override { return (double) m_integer; };
+	std::string getStringValue() override { return std::to_string(m_integer); };
 
-	int m_integer;
+	int compare(ColValue * other) override;
+
+	long m_integer;
     };
 
 
@@ -42,9 +52,11 @@ namespace usql {
 	ColDoubleValue(double value) : m_double(value) {};
 	ColDoubleValue(const ColDoubleValue &other) : m_double(other.m_double) {}
 
-	virtual long getIntValue() { return (long) m_double; };
-	virtual double getDoubleValue() { return m_double; };
-	virtual std::string getStringValue() { return std::to_string(m_double); };
+	long getIntValue() override { return (long) m_double; };
+	double getDoubleValue() override { return m_double; };
+	std::string getStringValue() override { return std::to_string(m_double); };
+
+	int compare(ColValue * other) override;
 
 	double m_double;
     };
@@ -52,12 +64,14 @@ namespace usql {
 
     struct ColStringValue : ColValue {
 
-	ColStringValue(const std::string value) : m_string(value) {};
+	ColStringValue(const std::string &value) : m_string(value) {};
 	ColStringValue(const ColStringValue &other) : m_string(other.m_string) {};
 
-	virtual long getIntValue() { return std::stoi(m_string); };
-	virtual double getDoubleValue() { return std::stod(m_string); };
-	virtual std::string getStringValue() { return m_string; };
+	long getIntValue() override { return std::stoi(m_string); };
+	double getDoubleValue() override { return std::stod(m_string); };
+	std::string getStringValue() override { return m_string; };
+
+	int compare(ColValue * other) override;
 
 	std::string m_string;
     };