Github user ajs6f commented on a diff in the pull request: https://github.com/apache/jena/pull/331#discussion_r157378417 --- Diff: jena-arq/src/main/java/org/apache/jena/sparql/function/library/FN_Error.java --- @@ -0,0 +1,66 @@ +/* + * 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; + +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 ; +import org.apache.jena.sparql.expr.nodevalue.NodeFunctions; +import org.apache.jena.sparql.function.FunctionBase; + +/** XPath and XQuery Functions and Operators 3.1 + * <p> + * {@code fn:error()} + * <br/> + * {@code fn:error(message)} + */ +public class FN_Error extends FunctionBase { + + @Override + public void checkBuild(String uri, ExprList args) { + if ( args.size() != 0 && args.size() != 1 ) + throw new QueryBuildException("Function '"+Lib.className(this)+"' takes zero or one arguments") ; + } + + @Override + public NodeValue exec(List<NodeValue> args) { + if ( args == null ) + // The contract on the function interface is that this should not happen. + throw new ARQInternalErrorException("FunctionBase1: Null args list") ; + + int size = args.size(); --- End diff -- Did you mean to use this `size` var below? It doesn't seem to get used at all...
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