solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/SequenceEvaluator.java

  /*
 * 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.solr.client.solrj.io.eval;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

import org.apache.commons.math3.util.MathArrays;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;

public class SequenceEvaluator extends RecursiveNumericEvaluator implements ManyValueWorker {
  protected static final long serialVersionUID = 1L;
  
  public SequenceEvaluator(StreamExpression expression, StreamFactory factory) throws IOException{
    super(expression, factory);
    
    if(3 != containedEvaluators.size()){
      throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting three values but found %d",expression, containedEvaluators.size()));
    }
  }

  @Override
  public Object doWork(Object... values) throws IOException {
    if(3 != values.length){
      throw new IOException(String.format(Locale.ROOT,"%s(...) only works with 3 values but %d were provided", constructingFactory.getFunctionName(getClass()), values.length));
    }
    
    Number sizeNum = (Number)values[0];
    Number startNum = (Number)values[1];
    Number strideNum = (Number)values[2];
    
    List<Number> sequence = new ArrayList<>(sizeNum.intValue());
    for(int number : MathArrays.sequence(sizeNum.intValue(), startNum.intValue(), strideNum.intValue())){
      sequence.add(number);
    }
    
    return sequence;
  }
}