org.apache.jena.sparql.function.library.strjoin.java Source code

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Here is the source code for org.apache.jena.sparql.function.library.strjoin.java

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/*
 * 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 org.apache.commons.logging.*;

import java.util.ArrayList;
import java.util.Iterator;
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.ExprList;
import org.apache.jena.sparql.expr.NodeValue;
import org.apache.jena.sparql.function.FunctionBase;

/** Function that concatenates strings using a separator.
 *  This is not fn:string-join because 
 *  (1) that takes a sequence as argument
 *  (2) the arguments are in a different order 
 */

public class strjoin extends FunctionBase {
    @Override
    public final NodeValue exec(List<NodeValue> args) {
        if (args == null)
            // The contract on the function interface is that this should not happen.
            throw new ARQInternalErrorException(Lib.className(this) + ": Null args list");

        Iterator<NodeValue> iter = args.iterator();
        String sep = iter.next().asString();

        List<String> x = new ArrayList<>();
        iter.forEachRemaining(arg -> x.add(arg.asString()));

        return NodeValue.makeString(String.join(sep, x));
    }

    @Override
    public void checkBuild(String uri, ExprList args) {
        if (args.size() < 1)
            throw new QueryBuildException("Function '" + Lib.className(this) + "' requires at least one arguments");
    }
}