add operator conversion for efficient parallelizing

src/parser.cpp

@@ -381,4 +381,15 @@ void print_token_vector(const std::vector<Expression::Token>& tv)
 	std::cout << "(" << *tv[i].to_str() << ")\n";
 }
 
+void print_math_vector(const std::vector<Expression::Token>& tv)
+{
+	int i, l;
+	for (i = 0, l = tv.size() - 1; i < l; i++)
+	{
+		std::cout << *tv[i].to_math_str() << " ";
+	}
+
+	std::cout << *tv[i].to_math_str() << "\n";
+}
+
 }