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ARQ is a SPARQL 1.1 query engine for Apache Jena

There is a newer version: 5.1.0

/*
 * 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;

import java.util.List ;

import org.apache.jena.atlas.lib.Lib ;
import org.apache.jena.query.QueryBuildException ;
import org.apache.jena.sparql.ARQInternalErrorException ;
import org.apache.jena.sparql.expr.ExprEvalException ;
import org.apache.jena.sparql.expr.ExprList ;
import org.apache.jena.sparql.expr.NodeValue ;

/** Support for a function of zero arguments. */

public abstract class FunctionBase0 extends FunctionBase
{
    @Override
    public void checkBuild(String uri, ExprList args)
    { 
        if ( args.size() != 0 )
            throw new QueryBuildException("Function '"+Lib.className(this)+"' takes no arguments") ;
    }
    
    @Override
    public final NodeValue exec(List args)
    {
        if ( args == null )
            // The contract on the function interface is that this should not happen.
            throw new ARQInternalErrorException("Function '"+Lib.className(this)+" Null args list") ;
        
        if ( args.size() != 0 )
            throw new ExprEvalException("Function '"+Lib.className(this)+" Wanted 0, got "+args.size()) ;
        
        return exec() ;
    }
    
    public abstract NodeValue exec() ;
}