content: package org.aion.db.utils.slices;
  
  import static java.nio.ByteOrder.LITTLE_ENDIAN;
  import static org.aion.db.utils.slices.SizeOf.SIZE_OF_BYTE;
  import static org.aion.db.utils.slices.SizeOf.SIZE_OF_INT;
  import static org.aion.db.utils.slices.SizeOf.SIZE_OF_LONG;
  import static org.aion.db.utils.slices.SizeOf.SIZE_OF_SHORT;
  
  import com.google.common.base.Preconditions;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  import java.nio.channels.ClosedChannelException;
  import java.nio.channels.FileChannel;
  import java.nio.channels.GatheringByteChannel;
  import java.nio.channels.ScatteringByteChannel;
  import java.nio.charset.Charset;
  import java.util.Arrays;
  
  /** Little Endian slice of a byte array. */
  public final class Slice implements Comparable<Slice> {
      private final byte[] data;
      private final int offset;
      private final int length;
  
      private int hash;
  
      public Slice(int length) {
          data = new byte[length];
          this.offset = 0;
          this.length = length;
      }
  
      public Slice(byte[] data) {
          Preconditions.checkNotNull(data, "array is null");
          this.data = data;
          this.offset = 0;
          this.length = data.length;
      }
  
      public Slice(byte[] data, int offset, int length) {
          Preconditions.checkNotNull(data, "array is null");
          this.data = data;
          this.offset = offset;
          this.length = length;
      }
  
      /** Length of this slice. */
      public int length() {
          return length;
      }
  
      /** Gets the array underlying this slice. */
      public byte[] getRawArray() {
          return data;
      }
  
      /** Gets the offset of this slice in the underlying array. */
      public int getRawOffset() {
          return offset;
      }
  
      /**
       * Gets a byte at the specified absolute {@code index} in this buffer.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or
       *     {@code index + 1} is greater than {@code this.capacity}
       */
      public byte getByte(int index) {
          Preconditions.checkPositionIndexes(index, index + SIZE_OF_BYTE, this.length);
          index += offset;
          return data[index];
      }
  
      /**
       * Gets an unsigned byte at the specified absolute {@code index} in this buffer.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or
       *     {@code index + 1} is greater than {@code this.capacity}
       */
      public short getUnsignedByte(int index) {
          return (short) (getByte(index) & 0xFF);
      }
  
      /**
       * Gets a 16-bit short integer at the specified absolute {@code index} in this slice.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or
       *     {@code index + 2} is greater than {@code this.capacity}
       */
      public short getShort(int index) {
          Preconditions.checkPositionIndexes(index, index + SIZE_OF_SHORT, this.length);
          index += offset;
          return (short) (data[index] & 0xFF | data[index + 1] << 8);
      }
  
      /**
       * Gets a 32-bit integer at the specified absolute {@code index} in this buffer.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or
       *     {@code index + 4} is greater than {@code this.capacity}
       */
      public int getInt(int index) {
          Preconditions.checkPositionIndexes(index, index + SIZE_OF_INT, this.length);
          index += offset;
          return (data[index] & 0xff)
                  | (data[index + 1] & 0xff) << 8
                  | (data[index + 2] & 0xff) << 16
                  | (data[index + 3] & 0xff) << 24;
      }
  
      /**
       * Gets a 64-bit long integer at the specified absolute {@code index} in this buffer.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or
       *     {@code index + 8} is greater than {@code this.capacity}
       */
      public long getLong(int index) {
          Preconditions.checkPositionIndexes(index, index + SIZE_OF_LONG, this.length);
          index += offset;
          return ((long) data[index] & 0xff)
                  | ((long) data[index + 1] & 0xff) << 8
                  | ((long) data[index + 2] & 0xff) << 16
                  | ((long) data[index + 3] & 0xff) << 24
                  | ((long) data[index + 4] & 0xff) << 32
                  | ((long) data[index + 5] & 0xff) << 40
                  | ((long) data[index + 6] & 0xff) << 48
                  | ((long) data[index + 7] & 0xff) << 56;
      }
  
      /**
       * Transfers this buffer's data to the specified destination starting at the specified absolute
       * {@code index}.
       *
       * @param dstIndex the first index of the destination
       * @param length the number of bytes to transfer
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0}, if
       *     the specified {@code dstIndex} is less than {@code 0}, if {@code index + length} is
       *     greater than {@code this.capacity}, or if {@code dstIndex + length} is greater than
       *     {@code dst.capacity}
       */
      public void getBytes(int index, Slice dst, int dstIndex, int length) {
          getBytes(index, dst.data, dstIndex, length);
      }
  
      /**
       * Transfers this buffer's data to the specified destination starting at the specified absolute
       * {@code index}.
       *
       * @param destinationIndex the first index of the destination
       * @param length the number of bytes to transfer
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0}, if
       *     the specified {@code dstIndex} is less than {@code 0}, if {@code index + length} is
       *     greater than {@code this.capacity}, or if {@code dstIndex + length} is greater than
       *     {@code dst.length}
       */
      public void getBytes(int index, byte[] destination, int destinationIndex, int length) {
          Preconditions.checkPositionIndexes(index, index + length, this.length);
          Preconditions.checkPositionIndexes(
                  destinationIndex, destinationIndex + length, destination.length);
          index += offset;
          System.arraycopy(data, index, destination, destinationIndex, length);
      }
  
      public byte[] getBytes() {
          return getBytes(0, length);
      }
  
      public byte[] getBytes(int index, int length) {
          index += offset;
          if (index == 0) {
              return Arrays.copyOf(data, length);
          } else {
              byte[] value = new byte[length];
              System.arraycopy(data, index, value, 0, length);
              return value;
          }
      }
  
      /**
       * Transfers this buffer's data to the specified destination starting at the specified absolute
       * {@code index} until the destination's position reaches its limit.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or if
       *     {@code index + dst.remaining()} is greater than {@code this.capacity}
       */
      public void getBytes(int index, ByteBuffer destination) {
          Preconditions.checkPositionIndex(index, this.length);
          index += offset;
          destination.put(data, index, Math.min(length, destination.remaining()));
      }
  
      /**
       * Transfers this buffer's data to the specified stream starting at the specified absolute
       * {@code index}.
       *
       * @param length the number of bytes to transfer
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or if
       *     {@code index + length} is greater than {@code this.capacity}
       * @throws java.io.IOException if the specified stream threw an exception during I/O
       */
      public void getBytes(int index, OutputStream out, int length) throws IOException {
          Preconditions.checkPositionIndexes(index, index + length, this.length);
          index += offset;
          out.write(data, index, length);
      }
  
      /**
       * Transfers this buffer's data to the specified channel starting at the specified absolute
       * {@code index}.
       *
       * @param length the maximum number of bytes to transfer
       * @return the actual number of bytes written out to the specified channel
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or if
       *     {@code index + length} is greater than {@code this.capacity}
       * @throws java.io.IOException if the specified channel threw an exception during I/O
       */
      public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
          Preconditions.checkPositionIndexes(index, index + length, this.length);
          index += offset;
          return out.write(ByteBuffer.wrap(data, index, length));
      }
  
      /**
       * Sets the specified 16-bit short integer at the specified absolute {@code index} in this
       * buffer. The 16 high-order bits of the specified value are ignored.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or
       *     {@code index + 2} is greater than {@code this.capacity}
       */
      public void setShort(int index, int value) {
          Preconditions.checkPositionIndexes(index, index + SIZE_OF_SHORT, this.length);
          index += offset;
          data[index] = (byte) (value);
          data[index + 1] = (byte) (value >>> 8);
      }
  
      /**
       * Sets the specified 32-bit integer at the specified absolute {@code index} in this buffer.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or
       *     {@code index + 4} is greater than {@code this.capacity}
       */
      public void setInt(int index, int value) {
          Preconditions.checkPositionIndexes(index, index + SIZE_OF_INT, this.length);
          index += offset;
          data[index] = (byte) (value);
          data[index + 1] = (byte) (value >>> 8);
          data[index + 2] = (byte) (value >>> 16);
          data[index + 3] = (byte) (value >>> 24);
      }
  
      /**
       * Sets the specified 64-bit long integer at the specified absolute {@code index} in this
       * buffer.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or
       *     {@code index + 8} is greater than {@code this.capacity}
       */
      public void setLong(int index, long value) {
          Preconditions.checkPositionIndexes(index, index + SIZE_OF_LONG, this.length);
          index += offset;
          data[index] = (byte) (value);
          data[index + 1] = (byte) (value >>> 8);
          data[index + 2] = (byte) (value >>> 16);
          data[index + 3] = (byte) (value >>> 24);
          data[index + 4] = (byte) (value >>> 32);
          data[index + 5] = (byte) (value >>> 40);
          data[index + 6] = (byte) (value >>> 48);
          data[index + 7] = (byte) (value >>> 56);
      }
  
      /**
       * Sets the specified byte at the specified absolute {@code index} in this buffer. The 24
       * high-order bits of the specified value are ignored.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or
       *     {@code index + 1} is greater than {@code this.capacity}
       */
      public void setByte(int index, int value) {
          Preconditions.checkPositionIndexes(index, index + SIZE_OF_BYTE, this.length);
          index += offset;
          data[index] = (byte) value;
      }
  
      /**
       * Transfers the specified source buffer's data to this buffer starting at the specified
       * absolute {@code index}.
       *
       * @param srcIndex the first index of the source
       * @param length the number of bytes to transfer
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0}, if
       *     the specified {@code srcIndex} is less than {@code 0}, if {@code index + length} is
       *     greater than {@code this.capacity}, or if {@code srcIndex + length} is greater than
       *     {@code src.capacity}
       */
      public void setBytes(int index, Slice src, int srcIndex, int length) {
          setBytes(index, src.data, src.offset + srcIndex, length);
      }
  
      /**
       * Transfers the specified source array's data to this buffer starting at the specified absolute
       * {@code index}.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0}, if
       *     the specified {@code srcIndex} is less than {@code 0}, if {@code index + length} is
       *     greater than {@code this.capacity}, or if {@code srcIndex + length} is greater than
       *     {@code src.length}
       */
      public void setBytes(int index, byte[] source, int sourceIndex, int length) {
          Preconditions.checkPositionIndexes(index, index + length, this.length);
          Preconditions.checkPositionIndexes(sourceIndex, sourceIndex + length, source.length);
          index += offset;
          System.arraycopy(source, sourceIndex, data, index, length);
      }
  
      /**
       * Transfers the specified source buffer's data to this buffer starting at the specified
       * absolute {@code index} until the source buffer's position reaches its limit.
       *
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or if
       *     {@code index + src.remaining()} is greater than {@code this.capacity}
       */
      public void setBytes(int index, ByteBuffer source) {
          Preconditions.checkPositionIndexes(index, index + source.remaining(), this.length);
          index += offset;
          source.get(data, index, source.remaining());
      }
  
      /**
       * Transfers the content of the specified source stream to this buffer starting at the specified
       * absolute {@code index}.
       *
       * @param length the number of bytes to transfer
       * @return the actual number of bytes read in from the specified channel. {@code -1} if the
       *     specified channel is closed.
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or if
       *     {@code index + length} is greater than {@code this.capacity}
       * @throws java.io.IOException if the specified stream threw an exception during I/O
       */
      public int setBytes(int index, InputStream in, int length) throws IOException {
          Preconditions.checkPositionIndexes(index, index + length, this.length);
          index += offset;
          int readBytes = 0;
          do {
              int localReadBytes = in.read(data, index, length);
              if (localReadBytes < 0) {
                  if (readBytes == 0) {
                      return -1;
                  } else {
                      break;
                  }
              }
              readBytes += localReadBytes;
              index += localReadBytes;
              length -= localReadBytes;
          } while (length > 0);
  
          return readBytes;
      }
  
      /**
       * Transfers the content of the specified source channel to this buffer starting at the
       * specified absolute {@code index}.
       *
       * @param length the maximum number of bytes to transfer
       * @return the actual number of bytes read in from the specified channel. {@code -1} if the
       *     specified channel is closed.
       * @throws IndexOutOfBoundsException if the specified {@code index} is less than {@code 0} or if
       *     {@code index + length} is greater than {@code this.capacity}
       * @throws java.io.IOException if the specified channel threw an exception during I/O
       */
      public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
          Preconditions.checkPositionIndexes(index, index + length, this.length);
          index += offset;
          ByteBuffer buf = ByteBuffer.wrap(data, index, length);
          int readBytes = 0;
  
          do {
              int localReadBytes;
              try {
                  localReadBytes = in.read(buf);
              } catch (ClosedChannelException e) {
                  localReadBytes = -1;
              }
              if (localReadBytes < 0) {
                  if (readBytes == 0) {
                      return -1;
                  } else {
                      break;
                  }
              } else if (localReadBytes == 0) {
                  break;
              }
              readBytes += localReadBytes;
          } while (readBytes < length);
  
          return readBytes;
      }
  
      public int setBytes(int index, FileChannel in, int position, int length) throws IOException {
          Preconditions.checkPositionIndexes(index, index + length, this.length);
          index += offset;
          ByteBuffer buf = ByteBuffer.wrap(data, index, length);
          int readBytes = 0;
  
          do {
              int localReadBytes;
              try {
                  localReadBytes = in.read(buf, position + readBytes);
              } catch (ClosedChannelException e) {
                  localReadBytes = -1;
              }
              if (localReadBytes < 0) {
                  if (readBytes == 0) {
                      return -1;
                  } else {
                      break;
                  }
              } else if (localReadBytes == 0) {
                  break;
              }
              readBytes += localReadBytes;
          } while (readBytes < length);
  
          return readBytes;
      }
  
      public Slice copySlice() {
          return copySlice(0, length);
      }
  
      /**
       * Returns a copy of this buffer's sub-region. Modifying the content of the returned buffer or
       * this buffer does not affect each other at all.
       */
      public Slice copySlice(int index, int length) {
          Preconditions.checkPositionIndexes(index, index + length, this.length);
  
          index += offset;
          byte[] copiedArray = new byte[length];
          System.arraycopy(data, index, copiedArray, 0, length);
          return new Slice(copiedArray);
      }
  
      public byte[] copyBytes() {
          return copyBytes(0, length);
      }
  
      public byte[] copyBytes(int index, int length) {
          Preconditions.checkPositionIndexes(index, index + length, this.length);
          index += offset;
          if (index == 0) {
              return Arrays.copyOf(data, length);
          } else {
              byte[] value = new byte[length];
              System.arraycopy(data, index, value, 0, length);
              return value;
          }
      }
  
      /**
       * Returns a slice of this buffer's readable bytes. Modifying the content of the returned buffer
       * or this buffer affects each other's content while they maintain separate indexes and marks.
       */
      public Slice slice() {
          return slice(0, length);
      }
  
      /**
       * Returns a slice of this buffer's sub-region. Modifying the content of the returned buffer or
       * this buffer affects each other's content while they maintain separate indexes and marks.
       */
      public Slice slice(int index, int length) {
          if (index == 0 && length == this.length) {
              return this;
          }
  
          Preconditions.checkPositionIndexes(index, index + length, this.length);
          if (index >= 0 && length == 0) {
              return Slices.EMPTY_SLICE;
          }
          return new Slice(data, offset + index, length);
      }
  
      /** Creates an input stream over this slice. */
      public SliceInput input() {
          return new SliceInput(this);
      }
  
      /** Creates an output stream over this slice. */
      public SliceOutput output() {
          return new BasicSliceOutput(this);
      }
  
      /**
       * Converts this buffer's readable bytes into a NIO buffer. The returned buffer shares the
       * content with this buffer.
       */
      public ByteBuffer toByteBuffer() {
          return toByteBuffer(0, length);
      }
  
      /**
       * Converts this buffer's sub-region into a NIO buffer. The returned buffer shares the content
       * with this buffer.
       */
      public ByteBuffer toByteBuffer(int index, int length) {
          Preconditions.checkPositionIndexes(index, index + length, this.length);
          index += offset;
          return ByteBuffer.wrap(data, index, length).order(LITTLE_ENDIAN);
      }
  
      @Override
      public boolean equals(Object o) {
          if (this == o) {
              return true;
          }
          if (o == null || getClass() != o.getClass()) {
              return false;
          }
  
          Slice slice = (Slice) o;
  
          // do lengths match
          if (length != slice.length) {
              return false;
          }
  
          // if arrays have same base offset, some optimizations can be taken...
          if (offset == slice.offset && data == slice.data) {
              return true;
          }
          for (int i = 0; i < length; i++) {
              if (data[offset + i] != slice.data[slice.offset + i]) {
                  return false;
              }
          }
          return true;
      }
  
      @Override
      public int hashCode() {
          if (hash != 0) {
              return hash;
          }
  
          int result = length;
          for (int i = offset; i < offset + length; i++) {
              result = 31 * result + data[i];
          }
          if (result == 0) {
              result = 1;
          }
          hash = result;
          return hash;
      }
  
      /**
       * Compares the content of the specified buffer to the content of this buffer. This comparison
       * is performed byte by byte using an unsigned comparison.
       */
      public int compareTo(Slice that) {
          if (this == that) {
              return 0;
          }
          if (this.data == that.data && length == that.length && offset == that.offset) {
              return 0;
          }
  
          int minLength = Math.min(this.length, that.length);
          for (int i = 0; i < minLength; i++) {
              int thisByte = 0xFF & this.data[this.offset + i];
              int thatByte = 0xFF & that.data[that.offset + i];
              if (thisByte != thatByte) {
                  return (thisByte) - (thatByte);
              }
          }
          return this.length - that.length;
      }
  
      /** Decodes this buffer's readable bytes into a string with the specified character set name. */
      public String toString(Charset charset) {
          return toString(0, length, charset);
      }
  
      /** Decodes this buffer's sub-region into a string with the specified character set. */
      public String toString(int index, int length, Charset charset) {
          if (length == 0) {
              return "";
          }
  
          return Slices.decodeString(toByteBuffer(index, length), charset);
      }
  
      public String toString() {
          return getClass().getSimpleName() + '(' + "length=" + length() + ')';
      }
  }
  