Rule.java

/*
 * Copyright (c) 2013-2015 Josef Hardi <josef.hardi@gmail.com>
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.obidea.semantika.expression.base;

import com.obidea.semantika.knowledgebase.TermSubstitutionBinding;

public class Rule extends AbstractDatalog implements IRule
{
   private static final long serialVersionUID = 629451L;

   public Rule(final IPredicate consequent)
   {
      super(consequent);
   }

   @Override
   public void apply(TermSubstitutionBinding binding)
   {
      mAllVars.removeAll(binding.getVariables());
      
      /*
       * Apply the substitution to the distinct variables and all variables
       */
      for (int i = 0; i < mDistVars.size(); i++) {
         IVariable var = mDistVars.get(i);
         if (binding.isBound(var)) {
            ITerm substitutedTerm = binding.replace(var);
            if (substitutedTerm instanceof IVariable) {
               mDistVars.set(i, (IVariable) substitutedTerm);
               mAllVars.add((IVariable) substitutedTerm);
            }
            else if (substitutedTerm instanceof IConstant) {
               mDistVars.remove(i);
               mConstants.add((IConstant) substitutedTerm);
            }
         }
      }
      /*
       * Apply the substitution to atoms in the body
       */
      for (final IAtom atom : getBody()) {
         atom.apply(binding);
      }
   }

   @Override
   public boolean equals(Object obj)
   {
      if (this == obj) {
         return true;
      }
      if (obj == null) {
         return false;
      }
      if (getClass() != obj.getClass()) {
         return false;
      }
      final Rule other = (Rule) obj;
      return getHead().equals(other.getHead()) && getBody().equals(other.getBody());
   }

   public void accept(IRuleVisitor visitor)
   {
      visitor.visit(this);
   }
}