projectionelem.java

这是外国一个开源推理机

/*  Sesame - Storage and Querying architecture for RDF and RDF Schema
 *  Copyright (C) 2001-2005 Aduna
 *
 *  Contact: 
 *  	Aduna
 *  	Prinses Julianaplein 14 b
 *  	3817 CS Amersfoort
 *  	The Netherlands
 *  	tel. [phone]
 *  	fax. [phone]
 *
 *  	http://aduna.biz/
 *  	http://www.openrdf.org/
 *  
 *  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 library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package org.openrdf.sesame.sail.query;


public class ProjectionElem {

/*----------+
| Variables |
+----------*/

	private ValueExpr _valueExpr;
	private String _alias;

/*-------------+
| Constructors |
+-------------*/

	public ProjectionElem(ValueExpr ve) {
		_valueExpr = ve;
	}

	public ProjectionElem(ValueExpr ve, String alias) {
		this(ve);
		_alias = alias;
	}

/*--------+
| Methods |
+--------*/

	public ValueExpr getValueExpr() {
		return _valueExpr;
	}

	public String getAlias() {
		return _alias;
	}

	/**
	 * Returns the alias if available, or the string-representation of the value
	 * expression otherwise.
	 **/
	public String getName() {
		if (_alias != null) {
			return _alias;
		}
		else {
			return _valueExpr.toString();
		}
	}

	// overrides Object.toString()
	public String toString() {
		String result = _valueExpr.toString();

		if (_alias != null) {
			result += " AS \"" + _alias + "\"";
		}

		return result;
	}
}