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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.hadoop.hive.serde2.lazy;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.serde2.SerDeStatsStruct;
import org.apache.hadoop.hive.serde2.lazy.objectinspector.LazySimpleStructObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.StructField;
import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector;
import org.apache.hadoop.io.Text;

/**
 * LazyObject for storing a struct. The field of a struct can be primitive or
 * non-primitive.
 *
 * LazyStruct does not deal with the case of a NULL struct. That is handled by
 * the parent LazyObject.
 */
public class LazyStruct extends LazyNonPrimitive implements
    SerDeStatsStruct {

  private static Log LOG = LogFactory.getLog(LazyStruct.class.getName());

  /**
   * Whether the data is already parsed or not.
   */
  boolean parsed;

  /**
   * Size of serialized data
   */
  long serializedSize;

  /**
   * The start positions of struct fields. Only valid when the data is parsed.
   * Note that startPosition[arrayLength] = begin + length + 1; that makes sure
   * we can use the same formula to compute the length of each element of the
   * array.
   */
  int[] startPosition;

  /**
   * The fields of the struct.
   */
  LazyObject[] fields;
  /**
   * Whether init() has been called on the field or not.
   */
  boolean[] fieldInited;

  /**
   * Construct a LazyStruct object with the ObjectInspector.
   */
  public LazyStruct(LazySimpleStructObjectInspector oi) {
    super(oi);
  }

  /**
   * Set the row data for this LazyStruct.
   *
   * @see LazyObject#init(ByteArrayRef, int, int)
   */
  @Override
  public void init(ByteArrayRef bytes, int start, int length) {
    super.init(bytes, start, length);
    parsed = false;
    serializedSize = length;
  }

  boolean missingFieldWarned = false;
  boolean extraFieldWarned = false;

  /**
   * Parse the byte[] and fill each field.
   */
  private void parse() {

    byte separator = oi.getSeparator();
    boolean lastColumnTakesRest = oi.getLastColumnTakesRest();
    boolean isEscaped = oi.isEscaped();
    byte escapeChar = oi.getEscapeChar();

    if (fields == null) {
      List fieldRefs = ((StructObjectInspector) oi)
          .getAllStructFieldRefs();
      fields = new LazyObject[fieldRefs.size()];
      for (int i = 0; i < fields.length; i++) {
        fields[i] = LazyFactory.createLazyObject(fieldRefs.get(i)
            .getFieldObjectInspector());
      }
      fieldInited = new boolean[fields.length];
      // Extra element to make sure we have the same formula to compute the
      // length of each element of the array.
      startPosition = new int[fields.length + 1];
    }

    int structByteEnd = start + length;
    int fieldId = 0;
    int fieldByteBegin = start;
    int fieldByteEnd = start;
    byte[] bytes = this.bytes.getData();

    // Go through all bytes in the byte[]
    while (fieldByteEnd <= structByteEnd) {
      if (fieldByteEnd == structByteEnd || bytes[fieldByteEnd] == separator) {
        // Reached the end of a field?
        if (lastColumnTakesRest && fieldId == fields.length - 1) {
          fieldByteEnd = structByteEnd;
        }
        startPosition[fieldId] = fieldByteBegin;
        fieldId++;
        if (fieldId == fields.length || fieldByteEnd == structByteEnd) {
          // All fields have been parsed, or bytes have been parsed.
          // We need to set the startPosition of fields.length to ensure we
          // can use the same formula to calculate the length of each field.
          // For missing fields, their starting positions will all be the same,
          // which will make their lengths to be -1 and uncheckedGetField will
          // return these fields as NULLs.
          for (int i = fieldId; i <= fields.length; i++) {
            startPosition[i] = fieldByteEnd + 1;
          }
          break;
        }
        fieldByteBegin = fieldByteEnd + 1;
        fieldByteEnd++;
      } else {
        if (isEscaped && bytes[fieldByteEnd] == escapeChar
            && fieldByteEnd + 1 < structByteEnd) {
          // ignore the char after escape_char
          fieldByteEnd += 2;
        } else {
          fieldByteEnd++;
        }
      }
    }

    // Extra bytes at the end?
    if (!extraFieldWarned && fieldByteEnd < structByteEnd) {
      extraFieldWarned = true;
      LOG.warn("Extra bytes detected at the end of the row! Ignoring similar "
          + "problems.");
    }

    // Missing fields?
    if (!missingFieldWarned && fieldId < fields.length) {
      missingFieldWarned = true;
      LOG.info("Missing fields! Expected " + fields.length + " fields but "
          + "only got " + fieldId + "! Ignoring similar problems.");
    }

    Arrays.fill(fieldInited, false);
    parsed = true;
  }

  /**
   * Get one field out of the struct.
   *
   * If the field is a primitive field, return the actual object. Otherwise
   * return the LazyObject. This is because PrimitiveObjectInspector does not
   * have control over the object used by the user - the user simply directly
   * use the Object instead of going through Object
   * PrimitiveObjectInspector.get(Object).
   *
   * @param fieldID
   *          The field ID
   * @return The field as a LazyObject
   */
  public Object getField(int fieldID) {
    if (!parsed) {
      parse();
    }
    return uncheckedGetField(fieldID);
  }

  /**
   * Get the field out of the row without checking parsed. This is called by
   * both getField and getFieldsAsList.
   *
   * @param fieldID
   *          The id of the field starting from 0.
   * @param nullSequence
   *          The sequence representing NULL value.
   * @return The value of the field
   */
  private Object uncheckedGetField(int fieldID) {
    Text nullSequence = oi.getNullSequence();
    // Test the length first so in most cases we avoid doing a byte[]
    // comparison.
    int fieldByteBegin = startPosition[fieldID];
    int fieldLength = startPosition[fieldID + 1] - startPosition[fieldID] - 1;
    if ((fieldLength < 0)
        || (fieldLength == nullSequence.getLength() && LazyUtils.compare(bytes
            .getData(), fieldByteBegin, fieldLength, nullSequence.getBytes(),
            0, nullSequence.getLength()) == 0)) {
      return null;
    }
    if (!fieldInited[fieldID]) {
      fieldInited[fieldID] = true;
      fields[fieldID].init(bytes, fieldByteBegin, fieldLength);
    }
    return fields[fieldID].getObject();
  }

  ArrayList