StringLength.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.hadoop.hive.ql.exec.vector.expressions;

import org.apache.hadoop.hive.ql.exec.vector.BytesColumnVector;
import org.apache.hadoop.hive.ql.exec.vector.LongColumnVector;
import org.apache.hadoop.hive.ql.exec.vector.VectorExpressionDescriptor;
import org.apache.hadoop.hive.ql.exec.vector.VectorizedRowBatch;

/**
 * Calculate the length of the strings in the input column vector, and store
 * it in the output column vector.
 */
public class StringLength extends VectorExpression {
  private static final long serialVersionUID = 1L;
  private int colNum;
  private int outputColumn;

  public StringLength(int colNum, int outputColumn) {
    this();
    this.colNum = colNum;
    this.outputColumn = outputColumn;
  }

  public StringLength() {
    super();
  }

  // Calculate the length of the UTF-8 strings in input vector and place results in output vector.
  @Override
  public void evaluate(VectorizedRowBatch batch) {

    if (childExpressions != null) {
      super.evaluateChildren(batch);
    }

    BytesColumnVector inputColVector = (BytesColumnVector) batch.cols[colNum];
    LongColumnVector outV = (LongColumnVector) batch.cols[outputColumn];
    int[] sel = batch.selected;
    int n = batch.size;
    byte[][] vector = inputColVector.vector;
    int [] start = inputColVector.start;
    int [] length = inputColVector.length;
    long[] resultLen = outV.vector;

    if (n == 0) {
      //Nothing to do
      return;
    }

    if (inputColVector.noNulls) {
      outV.noNulls = true;
      if (inputColVector.isRepeating) {
        outV.isRepeating = true;
        resultLen[0] = utf8StringLength(vector[0], start[0], length[0]);
      } else if (batch.selectedInUse) {
        for(int j = 0; j != n; j++) {
          int i = sel[j];
          resultLen[i] = utf8StringLength(vector[i], start[i], length[i]);
        }
        outV.isRepeating = false;
      } else {
        for(int i = 0; i != n; i++) {
          resultLen[i] = utf8StringLength(vector[i], start[i], length[i]);
        }
        outV.isRepeating = false;
      }
    } else {

      /*
       * Handle case with nulls. Don't do function if the value is null, to save time,
       * because calling the function can be expensive.
       */
      outV.noNulls = false;
      if (inputColVector.isRepeating) {
        outV.isRepeating = true;
        outV.isNull[0] = inputColVector.isNull[0];
        if (!inputColVector.isNull[0]) {
          resultLen[0] = utf8StringLength(vector[0], start[0], length[0]);
        }
      } else if (batch.selectedInUse) {
        for(int j = 0; j != n; j++) {
          int i = sel[j];
          if (!inputColVector.isNull[i]) {
            resultLen[i] = utf8StringLength(vector[i], start[i], length[i]);
          }
          outV.isNull[i] = inputColVector.isNull[i];
        }
        outV.isRepeating = false;
      } else {
        for(int i = 0; i != n; i++) {
          if (!inputColVector.isNull[i]) {
            resultLen[i] = utf8StringLength(vector[i], start[i], length[i]);
          }
          outV.isNull[i] = inputColVector.isNull[i];
        }
        outV.isRepeating = false;
      }
    }
  }

  /*
   * Return length in characters of UTF8 string in byte array
   * beginning at start that is len bytes long.
   */
  static long utf8StringLength(byte[] s, int start, int len) {
    long resultLength = 0;
    for (int i = start; i < start + len; i++) {

      /* Byte bit patterns of the form 10xxxxxx are continuation
       * bytes. All other bit patterns are the first byte of
       * a character.
       */
      if ((s[i] & 0xc0) != 0x80) {
        resultLength++;
      }
    }
    return resultLength;
  }

  @Override
  public int getOutputColumn() {
    return outputColumn;
  }

  @Override
  public String getOutputType() {
    return "Long";
  }

  public int getColNum() {
    return colNum;
  }

  public void setColNum(int colNum) {
    this.colNum = colNum;
  }

  public void setOutputColumn(int outputColumn) {
    this.outputColumn = outputColumn;
  }

  public String vectorExpressionParameters() {
    return "col " + colNum;
  }

  @Override
  public VectorExpressionDescriptor.Descriptor getDescriptor() {
    VectorExpressionDescriptor.Builder b = new VectorExpressionDescriptor.Builder();
    b.setMode(VectorExpressionDescriptor.Mode.PROJECTION)
        .setNumArguments(1)
        .setArgumentTypes(
            VectorExpressionDescriptor.ArgumentType.STRING_FAMILY)
        .setInputExpressionTypes(
            VectorExpressionDescriptor.InputExpressionType.COLUMN);
    return b.build();
  }
}