/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.jena.sparql.function.library.leviathan;
import java.math.BigInteger;
import org.apache.jena.sparql.expr.ExprEvalException ;
import org.apache.jena.sparql.expr.NodeValue ;
import org.apache.jena.sparql.function.FunctionBase1 ;
public class factorial extends FunctionBase1 {
@Override
public NodeValue exec(NodeValue v) {
BigInteger i = v.getInteger();
switch (i.compareTo(BigInteger.ZERO)) {
case 0:
// 0! is 1
return NodeValue.makeInteger(BigInteger.ONE);
case -1:
// Negative factorial is error
throw new ExprEvalException("Cannot evaluate a negative factorial");
case 1:
BigInteger res = i.add(BigInteger.ZERO);
i = i.subtract(BigInteger.ONE);
while (i.compareTo(BigInteger.ZERO) != 0) {
res = res.multiply(i);
i = i.subtract(BigInteger.ONE);
}
return NodeValue.makeInteger(res);
default:
throw new ExprEvalException("Unexpecte comparison result");
}
}
}