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/*
    This file is part of JLog.

    Created by Glendon Holst for Alan Mackworth and the 
    "Computational Intelligence: A Logical Approach" text.
    
    Copyright 1998, 2000, 2002 by University of British Columbia and 
    Alan Mackworth.
    
    This notice must remain in all files which belong to, or are derived 
    from JLog.
    
    Check  or 
     for further information
    about JLog, or to contact the authors.
     
    JLog 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.

    JLog 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 JLog; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    URLs:  or 
*/
//#########################################################################
//	Name
//#########################################################################
 
package ubc.cs.JLog.Builtins;

import java.lang.*;
import java.util.*;
import ubc.cs.JLog.Terms.*;
import ubc.cs.JLog.Foundation.*;
import ubc.cs.JLog.Builtins.Goals.*;

public class jName extends jBinaryBuiltinPredicate
{
 protected boolean 		prefer_atom;
 
 public jName(jTerm l,jTerm r)
 {
  this(l,r,false);
 };

 public jName(jTerm l,jTerm r,boolean pa)
 {
  super(l,r,TYPE_BUILTINPREDICATE);
  prefer_atom = pa; 
 };
  
 public String 		getName()
 {
  return "name";
 };

 public boolean 	prove(jNameGoal ng)
 {jTerm 	l,r;
  
  l = ng.lhs.getTerm();
  r = ng.rhs.getTerm();
  
  if ((l instanceof iPredicate && ((iPredicate) l).getArity() == 0) || 
		(l.type == TYPE_INTEGER) || (l.type == TYPE_REAL))
  {String 		s;
   jList 		il;
   
   if (l.type == TYPE_REAL)
    s = String.valueOf(((jReal) l).getRealValue());
   if (l.type == TYPE_INTEGER)
    s = String.valueOf(((jInteger) l).getIntegerValue());
   else
    s = l.getName();

   il = convertStringToList(s);
   return r.unify(il,ng.unified);  
  }
  else if (r instanceof jList)
  {String 		s;
   jTerm 		t;
   
   s = convertListToString((jList) r);
   t = convertStringToTerm(s,ng.prefer_atom);
   
   return l.unify(t,ng.unified);
  }
  else
   throw new InvalidNameArgumentException();
 };

 protected jTerm 	convertStringToTerm(String s,boolean pa)
 {
  if (pa)
   return new jAtom(s);
  
  // try to create an integer first
  try
  {
   return new jInteger(Integer.parseInt(s));
  }
  catch (NumberFormatException e)
  {
   // do nothing
  }
  // try to create a real next
  try
  {
   return new jReal(Float.parseFloat(s));
  }
  catch (NumberFormatException e)
  {
   return new jAtom(s);
  }
 };

 protected String 	convertListToString(jList i)
 {StringBuffer 		sb = new StringBuffer();
  jTerm 			t = i;
  
  while (t.type == TYPE_LIST)
  {jListPair 	l = (jListPair) t;
   jTerm 	it;
  
   it = l.getHead().getTerm();
   
   if (it.type != TYPE_INTEGER)
    throw new InvalidNameArgumentException();
    
   sb.append((char) ((jInteger) it).getIntegerValue());
   
   t = l.getTail().getTerm();
  }
    
  return sb.toString();
 }; 	
 
 protected jList 	convertStringToList(String s)
 {int 		i,max = s.length();
  jList 	head = null;
  jListPair 	prev = null;
  
  for (i = 0; i < max; i++)
  {jListPair 	next;
  
   next = new jListPair(new jInteger((int) s.charAt(i)),null);
   
   if (prev == null)
    head = next;
   else
    prev.setTail(next);
    
   prev = next;
  }
  
  if (prev == null)
   head = jNullList.NULL_LIST;
  else
   prev.setTail(jNullList.NULL_LIST);
    
  return head;
 }; 	
 
 public void 		addGoals(jGoal g,jVariable[] vars,iGoalStack goals)
 {
  goals.push(new jNameGoal(this,lhs.duplicate(vars),rhs.duplicate(vars),prefer_atom));
 };

 public void 		addGoals(jGoal g,iGoalStack goals)
 {
  goals.push(new jNameGoal(this,lhs,rhs,prefer_atom));
 };

 protected jBinaryBuiltinPredicate 		duplicate(jTerm lhs,jTerm rhs)
 {
  return new jName(lhs,rhs,prefer_atom); 
 };
};