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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 
*/
//#########################################################################
//	OrPredicate
//#########################################################################

package ubc.cs.JLog.Terms;

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

public class jOrPredicate extends iPredicate implements iMakeUnmake
{
 protected Vector 		predicateterms;
 
 public jOrPredicate()
 {
  predicateterms = new Vector();
  type = TYPE_ORPREDICATE;
 };
 
 protected jOrPredicate(Vector t)
 {
  predicateterms = t;
  type = TYPE_ORPREDICATE;
 };

 public String 		getName()
 {
  return ";";
 };
 
 public int 		getArity()
 {
  return predicateterms.size();
 };

 public jCompoundTerm 	getArguments()
 {jCompoundTerm 	ct = new jCompoundTerm();
  Enumeration 		e = predicateterms.elements();
  
  while (e.hasMoreElements())
   ct.addTerm((jPredicateTerms) e.nextElement());
  
  return ct;
 };

 protected int 		compareArguments(iPredicate ipred,boolean first_call,boolean var_equal)
 {
  if (ipred instanceof jOrPredicate)
  {Vector 		pt = ((jOrPredicate) ipred).predicateterms;
   int 			i,max = predicateterms.size();
   int 			result;

   // both vectors being the same size is a pre-condition   
   for (i = 0; i < max; i++)
   {
    result = ((jPredicateTerms) predicateterms.elementAt(i)).
                                compare((jPredicateTerms) pt.elementAt(i),true,var_equal);
    if (result != EQUAL)
     return result; 
   }
   return EQUAL;
  }
  
  return (first_call ? -ipred.compareArguments(this,false,var_equal) : EQUAL);
 };

 public void 			addPredicateTerms(jPredicateTerms t)
 {
  predicateterms.addElement(t); 
 };
 
 public void 			removePredicateTerms(jPredicateTerms t)
 {
  predicateterms.removeElement(t);
 };
 
 public Enumeration 	enumPredicateTerms()
 {
  return predicateterms.elements();
 };
 
 public int 			size()
 {
  return predicateterms.size();
 };
 
 public jPredicateTerms 			elementAt(int index)
 {
  return (jPredicateTerms) predicateterms.elementAt(index);
 };
 
 public boolean 		isEmpty()
 {
  return predicateterms.isEmpty();
 };
 
 public boolean 	equivalence(jTerm term,jEquivalenceMapping v)
 {jTerm t = term.getTerm();

  // only equiv with other terms of same type
  if (type != t.type)
   return false;
 
  // altough we cannot be certain that term is a jOrPredicate, if it is not then type 
  // was wrong so this warrents a failing exception.
  {jOrPredicate 	orpred;
   int 				sz;
   
   orpred = (jOrPredicate) t;
   
   // only unify if terms have same size
   if ((sz = predicateterms.size()) != orpred.predicateterms.size())
    return false;

   {int 		i;
   
    // equiv each element of orpredicate, exit on first failure.
    for (i = 0; i < sz; i++)
     if (!((jPredicateTerms) predicateterms.elementAt(i)).equivalence(
             (jPredicateTerms) orpred.predicateterms.elementAt(i),v))
      return false;
   }    
  }   
  return true;
 };

 public boolean 	unify(jTerm term,jUnifiedVector v)
 {
  // if term is variable we let it handle the unification
  if (term.type == TYPE_VARIABLE)
   return term.unify(this,v);

  // only unify with other terms of same type
  if (type != term.type)
   return false;
 
  // altough we cannot be certain that term is a jOrPredicate, if it is not then type 
  // was wrong so this warrents a failing exception.
  {jOrPredicate 	orpred;
   int 				sz;
   
   orpred = (jOrPredicate) term;
   
   // only unify if terms have same size
   if ((sz = predicateterms.size()) != orpred.predicateterms.size())
    return false;

   {int 		i;
   
    // unify each element of orpredicate, exit on first unification failure.
    for (i = 0; i < sz; i++)
     if (!((jPredicateTerms) predicateterms.elementAt(i)).unify(
             (jPredicateTerms) orpred.predicateterms.elementAt(i),v))
      return false;
   }    
  }   
  return true;
 };

 public boolean 	requiresCompleteVariableState()
 {Enumeration 	e;
 
  e = predicateterms.elements();
  
  while (e.hasMoreElements())
   if (((jPredicateTerms) e.nextElement()).requiresCompleteVariableState())
    return true;
  
  return false;
 };
 
 public void 		registerUnboundVariables(jUnifiedVector v)
 {int 		i,sz = predicateterms.size();
 
  for (i = 0; i < sz; i++)
   ((jPredicateTerms) predicateterms.elementAt(i)).registerUnboundVariables(v);
 };

 public void 		registerVariables(jVariableVector v)
 {Enumeration 	e;
 
  e = predicateterms.elements();
  
  while (e.hasMoreElements())
   ((jPredicateTerms) e.nextElement()).registerVariables(v);
 };
 
 public void 		enumerateVariables(jVariableVector v,boolean all)
 {Enumeration 	e;
 
  e = predicateterms.elements();
  
  while (e.hasMoreElements())
   ((jPredicateTerms) e.nextElement()).enumerateVariables(v,all);
 };

 public jTerm 		duplicate(jVariable[] vars)
 {int 				i,sz = predicateterms.size();
  Vector 			t = new Vector(sz);  

  for (i = 0;i < sz;i++)  
   t.addElement(((jPredicateTerms) predicateterms.elementAt(i)).duplicate(vars));
  
  return new jOrPredicate(t);
 };
 
 public jTerm 		copy(jVariableRegistry vars)
 {int 				i,sz = predicateterms.size();
  Vector 			t = new Vector(sz);  

  for (i = 0;i < sz;i++)  
   t.addElement(((jPredicateTerms) predicateterms.elementAt(i)).copy(vars));
  
  return new jOrPredicate(t);
 };

 public void 		consult(jKnowledgeBase kb)
 {Enumeration 	e;
 
  e = enumPredicateTerms();
  
  while (e.hasMoreElements())
   ((iConsultable) e.nextElement()).consult(kb);
 };
 
 public void 		consultReset()
 {Enumeration 	e;
 
  e = enumPredicateTerms();
  
  while (e.hasMoreElements())
   ((iConsultable) e.nextElement()).consultReset();
 };
 
 public String 		toString(boolean usename)
 {StringBuffer 	sb = new StringBuffer();
  Enumeration 	e;
  boolean 		first = true;
  
  e = predicateterms.elements();
  
  while (e.hasMoreElements())
  {
   if (!first)
    sb.append(";");
   sb.append(((jPredicateTerms) e.nextElement()).toString(usename));
   
   first = false;
  }
  
  return sb.toString();
 };

 public void 		addGoals(jGoal g,jVariable[] vars,iGoalStack goals)
 {
  goals.push(new jOrGoalWVars(this,g,vars,(goals.empty() ? null : goals.peek())));
 }; 

 public void 		addGoals(jGoal g,iGoalStack goals)
 {
  goals.push(new jOrGoal(this,g,(goals.empty() ? null : goals.peek())));
 }; 

 public final boolean 	prove(jOrGoal og,jGoal g,jVariable[] vars,iGoalStack goals)
 {int 	next_pterm;
 
  if ((next_pterm = og.getNextPredicateTermNumber()) < predicateterms.size())
  {
   ((jPredicateTerms) predicateterms.elementAt(next_pterm)).addGoals(g,vars,goals);
   return true;
  }
 
  return false;
 };

 public final boolean 	prove(jOrGoal og,jGoal g,iGoalStack goals)
 {int 	next_pterm;
 
  if ((next_pterm = og.getNextPredicateTermNumber()) < predicateterms.size())
  {
   ((jPredicateTerms) predicateterms.elementAt(next_pterm)).addGoals(g,goals);
   return true;
  }
 
  return false;
 };

 public boolean 		retry(jOrGoal og)
 {
  return (og.getPredicateTermNumber() < predicateterms.size());
 };
 
 public void 		make(jTerm t)
 {
  predicateterms.removeAllElements();
  makeOrPredicate(t);
 };
 
 public void 		makeOrPredicate(jTerm t)
 {
 };
 
 public jTerm 		unmake()
 {
  return unmakeOrPredicate();
 };
 
 public synchronized jTerm 		unmakeOrPredicate()
 {int 		i;
  jTerm 	prev = null;
 
  for (i = predicateterms.size() - 1; i >= 0; i--)
  {jPredicateTerms 	curr = (jPredicateTerms) predicateterms.elementAt(i);
  
   if (prev == null)
    prev = curr.unmakePredicateTerms();
   else
    prev = new jOr(curr.unmakePredicateTerms(),prev);
  }
  return prev;
 };
};