// file:    extractFromSexp.java
// author:  Robert Keller
//
// purpose: Showing how to extract information from an S expression
//
// action:  Repeatedly reads S expressions and "extracts" information from 
//          them 
//
// run:     java -cs analyzeSexp

// $Id: extractFromSexp.java,v 1.3 1997/02/10 04:14:05 keller Exp keller $

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

class extractFromSexp
  {
  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;

    while( (ob = prompt(in, out)) != Tokenizer.eof )       // read next S exp
      {
      if( ob instanceof Long )
        {
        long value = ((Long)ob).longValue();               // handle long
        out.println("Long: " + value);
        }

      else if( ob instanceof Double )
        {
        double value = ((Double)ob).doubleValue();         // handle double
        out.println("Double: " + value);
        }

      else if( ob instanceof String )                  
        {
        String value = (String)ob;                         // handle string
        out.println("String: " + value);
        }

      else if( ob instanceof Poly.List )
        {
        Object array[] = ((Poly.List)ob).array();	   // convert to array

        out.print("A list of length " + array.length);

        out.println( array.length > 0  ?  " consisting of:"  :  "");
      
        for( int i = 0; i < array.length; i++ )           // traverse the array
          {
          out.println("  " + i + ": " + array[i]);    
          }
        }

      else out.println(Poly.List.analysis(ob));            // other
      }
    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
    }
  }