solr/solrj/src/java/org/apache/solr/client/solrj/io/eval/PrimesEvaluator.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.primes.Primes;
import org.apache.solr.client.solrj.io.stream.expr.StreamExpression;
import org.apache.solr.client.solrj.io.stream.expr.StreamFactory;

public class PrimesEvaluator extends RecursiveNumericEvaluator implements ManyValueWorker {
  protected static final long serialVersionUID = 1L;

  public PrimesEvaluator(StreamExpression expression, StreamFactory factory) throws IOException{
    super(expression, factory);

    if(2 != containedEvaluators.size()){
      throw new IOException(String.format(Locale.ROOT,"Invalid expression %s - expecting two values but found %d",expression, containedEvaluators.size()));
    }
  }

  @Override
  public Object doWork(Object... values) throws IOException {
    if(2 != values.length){
      throw new IOException(String.format(Locale.ROOT,"%s(...) only works with 2 values but %d were provided", constructingFactory.getFunctionName(getClass()), values.length));
    }

    int sizeNum = ((Number)values[0]).intValue();
    int startNum = ((Number)values[1]).intValue();
    List<Number> primes = new ArrayList<>();

    for(int i=0; i< sizeNum; i++) {
      int prime = Primes.nextPrime(startNum);
      primes.add(prime);
      startNum = prime;
      ++startNum;
    }

    return primes;
  }
}