core/src/main/java/org/apache/accumulo/core/client/lexicoder/impl/ByteUtils.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.accumulo.core.client.lexicoder.impl;

import java.util.ArrayList;

public class ByteUtils {

  /**
   * Escapes 0x00 with 0x01 0x01 and 0x01 with 0x01 0x02
   */
  public static byte[] escape(byte[] in) {
    int escapeCount = 0;
    for (int i = 0; i < in.length; i++) {
      if (in[i] == 0x00 || in[i] == 0x01) {
        escapeCount++;
      }
    }

    if (escapeCount == 0)
      return in;

    byte ret[] = new byte[escapeCount + in.length];
    int index = 0;

    for (int i = 0; i < in.length; i++) {
      switch (in[i]) {
        case 0x00:
          ret[index++] = 0x01;
          ret[index++] = 0x01;
          break;
        case 0x01:
          ret[index++] = 0x01;
          ret[index++] = 0x02;
          break;
        default:
          ret[index++] = in[i];
      }
    }

    return ret;
  }

  /**
   * Unescapes 0x00 0x01 0x01 with 0x00 and 0x01 0x01 0x2 with 0x01
   */
  public static byte[] unescape(byte[] in) {
    int escapeCount = 0;
    for (int i = 0; i < in.length; i++) {
      if (in[i] == 0x01) {
        escapeCount++;
        i++;
      }
    }

    if (escapeCount == 0)
      return in;

    byte ret[] = new byte[in.length - escapeCount];

    int index = 0;
    for (int i = 0; i < in.length; i++) {
      if (in[i] == 0x01) {
        i++;
        ret[index++] = (byte) (in[i] - 1);
      } else {
        ret[index++] = in[i];
      }

    }

    return ret;
  }

  /**
   * Splits a byte array by 0x00
   */
  public static byte[][] split(byte[] data) {
    return split(data, 0, data.length);
  }

  /**
   * Splits a byte array by 0x00
   */
  public static byte[][] split(byte[] data, int dataOffset, int len) {
    ArrayList<Integer> offsets = new ArrayList<>();

    for (int i = dataOffset; i < (dataOffset + len); i++) {
      if (data[i] == 0x00) {
        offsets.add(i);
      }
    }

    offsets.add(dataOffset + len);

    byte[][] ret = new byte[offsets.size()][];

    int index = dataOffset;
    for (int i = 0; i < offsets.size(); i++) {
      ret[i] = new byte[offsets.get(i) - index];
      System.arraycopy(data, index, ret[i], 0, ret[i].length);
      index = offsets.get(i) + 1;
    }

    return ret;
  }

  /**
   * Concatenates byte arrays with 0x00 as a delimiter
   */
  public static byte[] concat(byte[]... fields) {
    int len = 0;
    for (byte[] field : fields) {
      len += field.length;
    }

    byte ret[] = new byte[len + fields.length - 1];
    int index = 0;

    for (byte[] field : fields) {
      System.arraycopy(field, 0, ret, index, field.length);
      index += field.length;
      if (index < ret.length)
        ret[index++] = 0x00;
    }

    return ret;
  }

}