/*
A simple lexical analyser that converts a string into a sequence of
tokens.  Java's StreamTokenizer can't be used since it only can
"push back" one token.
     
This will convert a string into a sequence of
tokens that can be inspected and processed in-order. It is a bit
of an overkill for the simple application, but makes actual
parsing later much easier and more robust than a quicker hack.
        
Copyright 2010-2011 Adam Pease, apease@articulatesoftware.com

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program ; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston,
MA  02111-1307 USA 
*/

package atp;

import java.io.*;
import java.util.*;
import java.util.regex.*;
import java.text.*;

public class Lexer {

    public int ttype = 0;
    public String sval = "";
       
    public static final String NoToken        = "No Token";
    public static final String WhiteSpace     = "White Space";
    public static final String Newline        = "Newline";
    public static final String HashComment    = "HashComment";
    public static final String PerComment     = "PerComment";
    public static final String IdentUpper     = "Identifier starting with capital letter";
    public static final String IdentLower     = "Identifier starting with lower case letter";
    public static final String DefFunctor     = "Defined symbol (starting with a $)";
    public static final String Number         = "Positive or negative Integer or real";
    public static final String QuotedString   = "Quoted string";   
    public static final String FullStop       = ". (full stop)";
    public static final String OpenPar        = "(";
    public static final String ClosePar       = ")";
    public static final String OpenSquare     = "[";
    public static final String CloseSquare    = "]";
    public static final String Comma          = ",";
    public static final String Colon          = ":";
    public static final String EqualSign      = "=";
    public static final String NotEqualSign   = "!=";
    public static final String Nand           = "~&";
    public static final String Nor            = "~|";
    public static final String Or             = "|";
    public static final String And            = "&";
    public static final String Implies        = "=>";   
    public static final String BImplies       = ""));              
        tokenDefs.put(Equiv,       Pattern.compile(""));                  
        tokenDefs.put(BImplies,    Pattern.compile("