// file:    prompter.java
// author:  Robert Keller
//
// purpose: Modification of echoSexp showing how to do a prompt
//
// action:  Repeatedly prompts single S expressions and prints them.
//
// run:     java -cs prompter

import Poly.*;                                             // cs 60 package
import java.io.*;

class prompter
  {
  static String promptString = " > ";                      // default prompt

  static int count = 1;                                    // line counter

  public static void main(String arg[])
    {
    Tokenizer in = new Tokenizer(System.in);               // S exp tokenizer

    PrintStream out = System.out;

    Object ob;                                             // Object to be read

    while( (ob = prompt(in, out)) != Tokenizer.eof )       // read next S exp
      {
      out.println(ob);                                     // echo the value
      }
    out.println();                                         // new line
    }

  static Object prompt(Tokenizer in, PrintStream out)      // prompt method
    {
    out.print(count++ + promptString);                     // display prompt
    out.flush();                                           // & increment count
    return in.nextSexp();                                  // get input
    }
  }