ubc.cs.JLog.Builtins.jAssert Maven / Gradle / Ivy

Go to download
/*
    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 
*/
//#########################################################################
//	Assert
//#########################################################################
 
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 jAssert extends jUnaryBuiltinPredicate
{
 public final static boolean 			FIRST = false;
 public final static boolean 			LAST = true;
 
 public jAssert(jTerm t)
 {
  super(t,TYPE_BUILTINPREDICATE);
 };
  
 public String 		getName()
 {
  return "assert";
 };

 public boolean 	prove(jAssertGoal ag,jKnowledgeBase kb)
 {jTerm 	t;
 
  t = ag.term.getTerm();
  
  if (t instanceof jIf)
  {jIf 					jif = (jIf) t;
   jTerm 				lhs = jif.getLHS().getTerm();
   jPredicate 			head = null;
   jPredicateTerms 		base = null;
   jVariableRegistry 	vars = new jVariableRegistry();
      
   if (lhs instanceof jPredicate)
    head = (jPredicate) lhs;
   else
    throw new InvalidAssertException("Expected single predicate before if operator in assert.");
    
   try
   {
    base = new jPredicateTerms();
    base.makePredicateTerms(jif.getRHS().getTerm());
   }
   catch (PredicateExpectedException e)
   {
    throw new InvalidAssertException("Expected predicates after if operator.");
   }
     
   return assertPredicate((jPredicate) head.copy(vars),(jPredicateTerms) base.copy(vars),kb,ag.addlast);
  }
  else if (t instanceof jPredicate)
  {
   return assertPredicate((jPredicate) t.copy(),null,kb,ag.addlast);
  }
  else if (t instanceof jAtom)
  {jPredicate 	tp = new jPredicate((jAtom) t);
   
   return assertPredicate(tp,null,kb,ag.addlast);
  }
  else
   throw new InvalidAssertException("Asserted term cannot be builtin or unbound variable.");
 };

 // h and b should be copied terms.  b may be null.
 protected boolean 		assertPredicate(jPredicate h,jPredicateTerms b,
                                        jKnowledgeBase kb,boolean addlast)
 {jRuleDefinitions 		rds;
  jRule 				rule;
  
  rule = new jRule(h,(b == null ? new jPredicateTerms() : b));
  if ((rds = h.getCachedRuleDefinitions()) == null)
   rds = kb.getRuleDefinitionsMatch(rule);
  
  if (rds == null)
  {
   kb.makeRuleDefinitionDynamic(rule);
   if (addlast)
    kb.addRuleLast(rule);
   else
    kb.addRuleFirst(rule);
  }
  else if (rds instanceof jDynamicRuleDefinitions)
  {
   if (addlast) 
    rds.addRuleLast(rule);
   else
    rds.addRuleFirst(rule);
  }
  else
   throw new InvalidAssertException("Asserted term '"+h.getName()+"/"+
                                      String.valueOf(h.getArity())+"' must be dynamic.");

  rule.consult(kb);
  return true;
 };
 
 public void 		addGoals(jGoal g,jVariable[] vars,iGoalStack goals)
 {
  goals.push(new jAssertGoal(this,rhs.duplicate(vars),LAST));
 };

 public void 		addGoals(jGoal g,iGoalStack goals)
 {
  goals.push(new jAssertGoal(this,rhs,LAST));
 };

 protected jUnaryBuiltinPredicate 		duplicate(jTerm r)
 {
  return new jAssert(r); 
 };
};