package it.unimi.dsi.mg4j.query.nodes;/*		  * MG4J: Managing Gigabytes for Java * * Copyright (C) 2006-2007 Sebastiano Vigna  * *  This library 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 library 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 program; if not, write to the Free Software *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * */import it.unimi.dsi.lang.MutableString;/** A node representing the logical not of the underlying query. *   * @author Sebastiano Vigna */public class Not implements Query {	/** The only underlying node. */	public final Query query;	public Not( final Query query ) {		this.query = query;	}		public String toString() {		return new MutableString().append( "! (" ).append( query ).append( ')' ).toString();	}	public <T> T accept( final QueryBuilderVisitor<T> visitor ) throws QueryBuilderVisitorException {		if ( ! visitor.visitPre( this ) ) return null;		final T result = query.accept( visitor );		if ( result == null ) return null;		return visitor.visitPost( this, result );	}	public boolean equals( final Object o ) {		if ( ! ( o instanceof Not) ) return false;		return query.equals( ((Not)o).query );	}		public int hashCode() {		return ~query.hashCode();	}}