/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-09 The eXist Project
* http://exist-db.org
*
* 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.util;
import java.math.BigInteger;
import java.util.Random;
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.XPathException;
import org.exist.xquery.XQueryContext;
import org.exist.xquery.value.DoubleValue;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.IntegerValue;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;
public class RandomFunction extends BasicFunction {
protected static final Logger logger = Logger.getLogger(RandomFunction.class);
public final static FunctionSignature signatures[] = {
new FunctionSignature(
new QName("random", UtilModule.NAMESPACE_URI, UtilModule.PREFIX),
"Returns a random number between 0.0 and 1.0",
null,
new FunctionReturnSequenceType(Type.DOUBLE, Cardinality.EXACTLY_ONE, "a random number between 0.0 and 1.0")
),
new FunctionSignature(
new QName("random-ulong", UtilModule.NAMESPACE_URI, UtilModule.PREFIX),
"Returns a random number between 0 and the maximum xs:unsignedLong",
null,
new FunctionReturnSequenceType(Type.UNSIGNED_LONG, Cardinality.EXACTLY_ONE, "a random number between 0 and the maximum xs:unsignedLong")
),
new FunctionSignature(
new QName("random", UtilModule.NAMESPACE_URI, UtilModule.PREFIX),
"Returns a random number between 0 (inclusive) and $max (exclusive), that is, a number greater than or equal to 0 but less than $max",
new SequenceType[] {
new FunctionParameterSequenceType("max", Type.INTEGER, Cardinality.EXACTLY_ONE, "A number to be used as the exclusive maximum value for the random number; the return value will be less than this number.")
},
new FunctionReturnSequenceType(Type.INTEGER, Cardinality.EXACTLY_ONE, "a random number between 0 and $max")
)
};
public RandomFunction(XQueryContext context, FunctionSignature signature) {
super(context, signature);
}
@Override
public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException {
final Sequence result;
final Random rnd = new Random();
if(getArgumentCount() == 0) {
if(isCalledAs("random")) {
result = new DoubleValue(rnd.nextDouble());
} else {
final BigInteger rndInt = new BigInteger(64, rnd);
result = new IntegerValue(rndInt, Type.UNSIGNED_LONG);
}
} else {
final IntegerValue upper = (IntegerValue)args[0].convertTo(Type.INTEGER);
result = new IntegerValue(rnd.nextInt(upper.getInt()));
}
return result;
}
}