+// Single command mode - command line arguments mode - evaluate the expression
+// given in the command line and quit
+fn run_command_line (args : &Vec<String>, match_num : ®ex::Regex) {
+ let mut expr = String::new ();
+ let mut i = 0;
+ // create the expression string to evaluate
+ for arg in args.iter() {
+ if i > 0 {
+ expr.push_str (&arg);
+ expr.push_str (" ");
+ }
+ i += 1;
+ }
+ // evaluate the result
+ let res = evaluate (&expr, &match_num);
+ // if Result is OK then print the result in green
+ if res.is_ok () {
+ let restxt = format! ("{}", res.unwrap());
+ println! ("{}", restxt.green ());
+ } else {
+ // print the error in purple
+ let errtxt = format! ("{}: {}", ERROR,
+ res.unwrap_err());
+ eprintln! ("{}", errtxt.purple ());
+ }
+}
+
+// Interactive mode - display the prompt and evaluate expressions entered into
+// the prompt - until user quits
+fn run_interactive_mode (match_num : ®ex::Regex) {