/* eXist Open Source Native XML Database
 * Copyright (C) 2000-03,  Wolfgang M. Meier (meier@ifs.tu-darmstadt.de)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public License
 * as published by the Free Software Foundation; either version 2
 * 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 Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library 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.
 * 
 * $Id$
 */

package org.exist.xquery.functions;

import org.exist.dom.QName;
import org.exist.xquery.Cardinality;
import org.exist.xquery.Function;
import org.exist.xquery.FunctionSignature;
import org.exist.xquery.Module;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.XPathException;
import org.exist.xquery.value.DoubleValue;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;

/**
 * xpath-library function: number(object)
 *
 */
public class FunNumber extends Function {

	public final static FunctionSignature signatures[] = {
		new FunctionSignature(
				new QName("number", Module.BUILTIN_FUNCTION_NS),
				new SequenceType[0],
				new SequenceType(Type.DOUBLE, Cardinality.EXACTLY_ONE)
		),
		new FunctionSignature(
			new QName("number", Module.BUILTIN_FUNCTION_NS),
			new SequenceType[] {
				 new SequenceType(Type.ATOMIC, Cardinality.ZERO_OR_ONE)},
			new SequenceType(Type.DOUBLE, Cardinality.EXACTLY_ONE)
		)
	};

	public FunNumber(XQueryContext context, FunctionSignature signature) {
		super(context, signature);
	}

	public Sequence eval(
		Sequence contextSequence,
		Item contextItem)
		throws XPathException {
		if (contextItem != null)
			contextSequence = contextItem.toSequence();
		Sequence arg = null;
		if(getSignature().getArgumentCount() == 1)
			arg = getArgument(0).eval(contextSequence);
		else
			arg = contextSequence;
		if(arg.getLength() == 0)
			return DoubleValue.NaN;
		else
			return arg.convertTo(Type.DOUBLE);
	}
}

@@ -2393,46 +2393,183 @@
 else
-%0A%09%09%09return arg.convertTo(Type.DOUBLE);
+ %7B%0A            try %7B%0A                return arg.convertTo(Type.DOUBLE);%0A            %7D catch(XPathException e) %7B%0A                return DoubleValue.NaN;%0A            %7D%0A        %7D
 %0A%09%7D%0A

Return NaN instead of an exception for values that cannot be converted to a double.