/*
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.xcmis.search.model.constraint;

import org.apache.commons.lang.Validate;
import org.xcmis.search.QueryObjectModelVisitor;
import org.xcmis.search.VisitException;
import org.xcmis.search.Visitors;

/**
 * A constraint that negates another constraint.
 */

public class Not extends Constraint
{
   private static final long serialVersionUID = 1L;

   private final Constraint constraint;


   /**
    * Create a constraint that negates another constraint.
    * 
    * @param constraint the constraint that is being negated
    * @throws IllegalArgumentException if the supplied constraint is null
    */
   public Not(Constraint constraint)
   {
      Validate.notNull(constraint, "The constraint argument may not be null");
      this.constraint = constraint;
   }

   /**
   * @see org.xcmis.search.model.QueryElement#accept(org.xcmis.search.QueryObjectModelVisitor)
   */

   public void accept(QueryObjectModelVisitor visitor) throws VisitException
   {

      visitor.visit(this);
   }

   /**
    * {@inheritDoc}
    * 
    * @see java.lang.Object#equals(java.lang.Object)
    */
   @Override
   public boolean equals(Object obj)
   {
      if (obj == null)
      {
         return false;
      }
      if (obj == this)
      {
         return true;
      }
      if (obj.getClass() != getClass())
      {
         return false;
      }
      Not rhs = (Not)obj;
      
      return this.constraint.equals(rhs.constraint);
   }

   /**
    * The constraint being negated.
    * 
    * @return the constraint; never null
    */
   public final Constraint getConstraint()
   {
      return constraint;
   }

   /**
     * {@inheritDoc}
     * 
     * @see java.lang.Object#hashCode()
     */
   @Override
   public int hashCode()
   {
      return getConstraint().hashCode();
   }

   /**
    * {@inheritDoc}
    * 
    * @see java.lang.Object#toString()
    */
   @Override
   public String toString()
   {
      return Visitors.readable(this);
   }
}