/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-09 Wolfgang M. Meier
* wolfgang@exist-db.org
* http://exist.sourceforge.net
*
* This program 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
* of the License, or (at your option) any later version.
*
* This program 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id: GetExists.java 2436 2006-01-07 21:47:15 +0000 (Sat, 07 Jan 2006) brihaye $
*/
package org.exist.xquery.functions.response;
import org.apache.log4j.Logger;
import org.exist.dom.QName;
import org.exist.xquery.BasicFunction;
import org.exist.xquery.Cardinality;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.Variable;
import org.exist.xquery.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.BooleanValue;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.Type;
/**
* DOCUMENT ME!
*
* @author Andrzej Taramina <andrzej@chaeron.com>
*/
public class GetExists extends BasicFunction
{
protected static final Logger logger = Logger.getLogger(GetExists.class);
public final static FunctionSignature signature =
new FunctionSignature(
new QName( "exists", ResponseModule.NAMESPACE_URI, ResponseModule.PREFIX ),
"Returns whether a response object exists.",
null,
new FunctionParameterSequenceType( "result", Type.BOOLEAN, Cardinality.EXACTLY_ONE, "true if the response object exists" ) );
/**
* Creates a new GetExists object.
*
* @param context
*/
public GetExists( XQueryContext context )
{
super( context, signature );
}
/* (non-Javadoc)
* @see org.exist.xquery.BasicFunction#eval(org.exist.xquery.value.Sequence[], org.exist.xquery.value.Sequence)
*/
public Sequence eval( Sequence[] args, Sequence contextSequence ) throws XPathException
{
BooleanValue exists = BooleanValue.TRUE;
ResponseModule myModule = (ResponseModule)context.getModule( ResponseModule.NAMESPACE_URI );
// response object is read from global variable $response
Variable var = myModule.resolveVariable( ResponseModule.RESPONSE_VAR );
if( ( var == null ) || ( var.getValue() == null ) ) {
exists = BooleanValue.FALSE;
}
return( exists );
}
}