/*
    * 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.hbase.util;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  
  /**
   * Lightweight, reusable class for specifying ranges of byte[]'s.
   * <p>
   * {@code ByteRange} maintains an underlying byte[] and a viewport into that
   * byte[] as a range of bytes. The {@code ByteRange} is a mutable, reusable
   * object, so the underlying byte[] can be modified after instantiation. This
   * is done using the {@link #set(byte[])} and {@link #unset()} methods. Direct
   * access to the byte[] is also available via {@link #getBytes()}. The viewport
   * is defined by an {@code offset} into the byte[] and a {@code length}. The
   * range of bytes is 0-indexed, and is accessed by index via the
   * {@link #get(int)} and {@link #put(int, byte)} methods.
   * </p>
   * <p>
   * This interface differs from ByteBuffer:
   * <li>On-heap bytes only</li>
   * <li>Raw {@code byte} access only; does not encode other primitives.</li>
   * <li>Implements {@code equals(Object)}, {@code #hashCode()}, and
   * {@code #compareTo(ByteRange)} so that it can be used in standard java
   * Collections. Comparison operations are lexicographic, which is native to
   * HBase.</li>
   * <li>Allows the addition of simple core methods like the deep and shallow
   * copy methods.</li>
   * <li>Can be reused in tight loops like a major compaction which can save
   * significant amounts of garbage. (Without reuse, we throw off garbage like
   * <a href="http://www.youtube.com/watch?v=lkmBH-MjZF4">this thing</a>.)</li>
   * </p>
   * <p>
   * Mutable, and always evaluates {@code #equals(Object)}, {@code #hashCode()},
   * and {@code #compareTo(ByteRange)} based on the current contents.
   * </p>
   * <p>
   * Can contain convenience methods for comparing, printing, cloning, spawning
   * new arrays, copying to other arrays, etc. Please place non-core methods into
   * {@link ByteRangeUtils}.
   * </p>
   */
  @InterfaceAudience.Public
  @InterfaceStability.Evolving
  public interface ByteRange extends Comparable<ByteRange> {
  
    /**
     * The underlying byte[].
     */
    public byte[] getBytes();
  
    /**
     * Nullifies this ByteRange. That is, it becomes a husk, being a range over
     * no byte[] whatsoever.
     * @return this
     */
    public ByteRange unset();
  
    /**
     * Reuse this {@code ByteRange} over a new byte[]. {@code offset} is set to
     * 0 and {@code length} is set to {@code capacity}.
     * @param capacity the size of a new byte[].
     * @return this
     */
    public ByteRange set(int capacity);
  
    /**
     * Reuse this {@code ByteRange} over a new byte[]. {@code offset} is set to
     * 0 and {@code length} is set to {@code bytes.length}. A null {@code bytes}
     * IS supported, in which case this method will behave equivalently to
     * {@link #unset()}.
     * @param bytes the array to wrap.
     * @return this
     */
    public ByteRange set(byte[] bytes);
  
    /**
     * Reuse this {@code ByteRange} over a new byte[]. A null {@code bytes} IS
     * supported, in which case this method will behave equivalently to
     * {@link #unset()}, regardless of the values of {@code offset} and
     * {@code length}.
     * @param bytes The array to wrap.
    * @param offset The offset into {@code bytes} considered the beginning of
    *            this range.
    * @param length The length of this range.
    * @return this.
    */
   public ByteRange set(byte[] bytes, int offset, int length);
 
   /**
    * The offset, the index into the underlying byte[] at which this range
    * begins.
    * @see #getBytes()
    */
   public int getOffset();
 
   /**
    * Update the beginning of this range. {@code offset + length} may not be
    * greater than {@code bytes.length}.
    * @param offset the new start of this range.
    * @return this.
    */
   public ByteRange setOffset(int offset);
 
   /**
    * The length of the range.
    */
   public int getLength();
 
   /**
    * Update the length of this range. {@code offset + length} should not be
    * greater than {@code bytes.length}.
    * @param length The new length of this range.
    * @return this.
    */
   public ByteRange setLength(int length);
 
   /**
    * @return true when this range is of zero length, false otherwise.
    */
   public boolean isEmpty();
 
   /**
    * Retrieve the byte at {@code index}.
    * @param index zero-based index into this range.
    * @return single byte at index.
    */
   public byte get(int index);
 
   /**
    * Retrieve the short value at {@code index}
    * @param index zero-based index into this range
    * @return the short value at {@code index}
    */
   public short getShort(int index);
 
   /**
    * Retrieve the int value at {@code index}
    * @param index zero-based index into this range
    * @return the int value at {@code index}
    */
   public int getInt(int index);
 
   /**
    * Retrieve the long value at {@code index}
    * @param index zero-based index into this range
    * @return the long value at {@code index}
    */
   public long getLong(int index);
 
   /**
    * Retrieve the long value at {@code index} which is stored as VLong
    * @param index zero-based index into this range
    * @return the long value at {@code index} which is stored as VLong
    */
   public long getVLong(int index);
 
   /**
    * Fill {@code dst} with bytes from the range, starting from {@code index}.
    * @param index zero-based index into this range.
    * @param dst the destination of the copy.
    * @return this.
    */
   public ByteRange get(int index, byte[] dst);
 
   /**
    * Fill {@code dst} with bytes from the range, starting from {@code index}.
    * {@code length} bytes are copied into {@code dst}, starting at {@code offset}.
    * @param index zero-based index into this range.
    * @param dst the destination of the copy.
    * @param offset the offset into {@code dst} to start the copy.
    * @param length the number of bytes to copy into {@code dst}.
    * @return this.
    */
   public ByteRange get(int index, byte[] dst, int offset, int length);
 
   /**
    * Store {@code val} at {@code index}.
    * @param index the index in the range where {@code val} is stored.
    * @param val the value to store.
    * @return this.
    */
   public ByteRange put(int index, byte val);
 
   /**
    * Store the short value at {@code index}
    * @param index the index in the range where {@code val} is stored
    * @param val the value to store
    * @return this
    */
   public ByteRange putShort(int index, short val);
 
   /**
    * Store the int value at {@code index}
    * @param index the index in the range where {@code val} is stored
    * @param val the value to store
    * @return this
    */
   public ByteRange putInt(int index, int val);
 
   /**
    * Store the long value at {@code index}
    * @param index the index in the range where {@code val} is stored
    * @param val the value to store
    * @return this
    */
   public ByteRange putLong(int index, long val);
 
   /**
    * Store the long value at {@code index} as a VLong
    * @param index the index in the range where {@code val} is stored
    * @param val the value to store
    * @return number of bytes written
    */
   public int putVLong(int index, long val);
 
   /**
    * Store {@code val} at {@code index}.
    * @param index the index in the range where {@code val} is stored.
    * @param val the value to store.
    * @return this.
    */
   public ByteRange put(int index, byte[] val);
 
   /**
    * Store {@code length} bytes from {@code val} into this range, starting at
    * {@code index}. Bytes from {@code val} are copied starting at {@code offset}
    * into the range.
    * @param index position in this range to start the copy.
    * @param val the value to store.
    * @param offset the offset in {@code val} from which to start copying.
    * @param length the number of bytes to copy from {@code val}.
    * @return this.
    */
   public ByteRange put(int index, byte[] val, int offset, int length);
 
   /**
    * Instantiate a new byte[] with exact length, which is at least 24 bytes +
    * length. Copy the contents of this range into it.
    * @return The newly cloned byte[].
    */
   public byte[] deepCopyToNewArray();
 
   /**
    * Create a new {@code ByteRange} with new backing byte[] containing a copy
    * of the content from {@code this} range's window.
    * @return Deep copy
    */
   public ByteRange deepCopy();
 
   /**
    * Wrapper for System.arraycopy. Copy the contents of this range into the
    * provided array.
    * @param destination Copy to this array
    * @param destinationOffset First index in the destination array.
    */
   public void deepCopyTo(byte[] destination, int destinationOffset);
 
   /**
    * Wrapper for System.arraycopy. Copy the contents of this range into the
    * provided array.
    * @param innerOffset Start copying from this index in this source
    *          ByteRange. First byte copied is bytes[offset + innerOffset]
    * @param copyLength Copy this many bytes
    * @param destination Copy to this array
    * @param destinationOffset First index in the destination array.
    */
   public void deepCopySubRangeTo(int innerOffset, int copyLength, byte[] destination,
       int destinationOffset);
 
   /**
    * Create a new {@code ByteRange} that points at this range's byte[].
    * Modifying the shallowCopy will modify the bytes in this range's array.
    * Pass over the hash code if it is already cached.
    * @return new {@code ByteRange} object referencing this range's byte[].
    */
   public ByteRange shallowCopy();
 
   /**
    * Create a new {@code ByteRange} that points at this range's byte[]. The new
    * range can have different values for offset and length, but modifying the
    * shallowCopy will modify the bytes in this range's array. Pass over the
    * hash code if it is already cached.
    * @param innerOffset First byte of clone will be this.offset + copyOffset.
    * @param copyLength Number of bytes in the clone.
    * @return new {@code ByteRange} object referencing this range's byte[].
    */
   public ByteRange shallowCopySubRange(int innerOffset, int copyLength);
 
 }