content: package com.github.aaronshan.functions.regexp;
  
  import io.airlift.slice.Slices;
  import java.util.ArrayList;
  import org.apache.hadoop.hive.ql.exec.Description;
  import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
  import org.apache.hadoop.hive.ql.exec.UDFArgumentLengthException;
  import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
  import org.apache.hadoop.hive.ql.metadata.HiveException;
  import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
  import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
  import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
  import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils;
  import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
  
  /**
   * @author ruifeng.shan
   * date: 2018-07-27
   * time: 22:38
   */
  @Description(name = "regexp_split"
          , value = "_FUNC_(string, string) - returns array of strings split by pattern."
          , extended = "Example:\n > select _FUNC_(string, pattern) from src;")
  public class UDFRe2JRegexpSplit extends GenericUDF {
      private static final int ARG_COUNT = 2;
      private transient ArrayList<Object> result = new ArrayList<Object>();
      private transient Re2JRegexp re2JRegexp;
  
      public UDFRe2JRegexpSplit() {
  
      }
  
      @Override
      public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException {
          // Check if two arguments were passed
          if (arguments.length != ARG_COUNT) {
              throw new UDFArgumentLengthException(
                      "The function regexp_split(string, pattern) takes exactly " + ARG_COUNT + " arguments.");
          }
  
          for (int i = 0; i < ARG_COUNT; i++) {
              if (!ObjectInspectorUtils.compareTypes(PrimitiveObjectInspectorFactory.javaStringObjectInspector, arguments[i])) {
                  throw new UDFArgumentTypeException(i,
                          "\"" + PrimitiveObjectInspectorFactory.javaStringObjectInspector.getTypeName() + "\" "
                                  + "expected at function regexp_split, but "
                                  + "\"" + arguments[i].getTypeName() + "\" "
                                  + "is found");
              }
          }
  
          ObjectInspector expectOI = PrimitiveObjectInspectorFactory.javaStringObjectInspector;
  
          return ObjectInspectorFactory.getStandardListObjectInspector(expectOI);
      }
  
      @Override
      public Object evaluate(DeferredObject[] arguments) throws HiveException {
          String source = (String) arguments[0].get();
          String pattern = (String) arguments[1].get();
  
          if (source == null) {
              return null;
          }
  
          if (re2JRegexp == null) {
              re2JRegexp = new Re2JRegexp(Integer.MAX_VALUE, 5, Slices.utf8Slice(pattern));
          }
  
          result.clear();
          result.addAll(re2JRegexp.split(Slices.utf8Slice(source)));
  
          return result;
      }
  
      @Override
      public String getDisplayString(String[] strings) {
          assert (strings.length == ARG_COUNT);
          return "regexp_split(" + strings[0] + ", "
                  + strings[1] + ")";
      }
  }