/*
 *  eXist Open Source Native XML Database
 *  Copyright (C) 2001-03 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.
 *  
 *  $Id$
 */
package org.exist.xquery.functions;

import java.text.Collator;

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

/**
 * @author Wolfgang Meier (wolfgang@exist-db.org)
 */
public class FunMax extends CollatingFunction {

	public final static FunctionSignature signatures[] = {
			new FunctionSignature(
					new QName("max", ModuleImpl.NAMESPACE_URI, ModuleImpl.PREFIX),
					"Selects an item from the input sequence $a whose value " +
					"is greater than or equal to the value of every other item in the " +
					"input sequence.",
					new SequenceType[] {
							new SequenceType(Type.ATOMIC, Cardinality.ZERO_OR_MORE)
					},
					new SequenceType(Type.ATOMIC, Cardinality.ZERO_OR_ONE)
			),
			new FunctionSignature(
					new QName("max", ModuleImpl.NAMESPACE_URI, ModuleImpl.PREFIX),
					"Selects an item from the input sequence $a whose value " +
					"is greater than or equal to the value of every other item in the " +
					"input sequence. The collation URI specified in $b will be used for " +
					"string comparisons.",
					new SequenceType[] {
							new SequenceType(Type.ATOMIC, Cardinality.ZERO_OR_MORE),
							new SequenceType(Type.STRING, Cardinality.EXACTLY_ONE)
					},
					new SequenceType(Type.ATOMIC, Cardinality.ZERO_OR_ONE)
			)
	};

	/**
	 * @param context
	 * @param signature
	 */
	public FunMax(XQueryContext context, FunctionSignature signature) {
		super(context, signature);
	}

	/* (non-Javadoc)
	 * @see org.exist.xquery.Expression#eval(org.exist.dom.DocumentSet, org.exist.xquery.value.Sequence, org.exist.xquery.value.Item)
	 */
	public Sequence eval(Sequence contextSequence, Item contextItem)
		throws XPathException {
		Sequence arg = getArgument(0).eval(contextSequence, contextItem);
		if(arg.getLength() == 0)
			return Sequence.EMPTY_SEQUENCE;
		Collator collator = getCollator(contextSequence, contextItem, 2);
		SequenceIterator iter = arg.iterate();
		AtomicValue max = (AtomicValue)iter.nextItem();
		if(max.getType() == Type.ATOMIC)
			max = max.convertTo(Type.DOUBLE);
		AtomicValue current;
		while(iter.hasNext()) {
			current = (AtomicValue)iter.nextItem();
			if(current.getType() == Type.ATOMIC)
				current = current.convertTo(Type.DOUBLE);
			if(Type.subTypeOf(current.getType(), Type.NUMBER) &&
				((NumericValue)current).isNaN())
				return DoubleValue.NaN;
				
			max = max.max(collator, current);
		}
		return max;
	}
}

@@ -960,16 +960,43 @@
 ollator;
+%0Aimport java.util.Iterator;
 %0A%0Aimport
@@ -3328,15 +3328,25 @@
 arg.
-i
+unorderedI
 terat
-e
+or
 ();%0A

Use unordered iterator instead of ordered one.