org.basex.util
Class Num

java.lang.Object
  org.basex.util.Num

public final class Num
extends Object

This class provides operations to compress and decompress integer values in byte arrays to save memory.

Author:

Workgroup DBIS, University of Konstanz 2005-10, ISC License, Christian Gruen

Method Summary

static byte[]	add(byte[] array, int val) Compresses and writes an integer value to the specified array and returns the array.
static int	len(byte[] array, int val) Returns integer length.
static int	len(int v) Returns the compressed length of the specified value.
static byte[]	newNum(int val) Creates a new number array.
static byte[]	num(int val) Creates a new number array.
static int	read(byte[] array, int pos) Reads and decompresses an integer value from the specified byte array.
static int	size(byte[] array) Returns the length of the specified array, stored in the first four bytes.
static void	size(byte[] array, int len) Writes the specified length in the first bytes of the specified array.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

newNum

public static byte[] newNum(int val)

Creates a new number array.

Parameters:

val - initial value to be stored

Returns:

new number array

num

public static byte[] num(int val)

Creates a new number array.

Parameters:

val - initial value to be stored

Returns:

new number array

add

public static byte[] add(byte[] array,
                         int val)

Compresses and writes an integer value to the specified array and returns the array.

Parameters:

array - array

val - value to be written

Returns:

new array

read

public static int read(byte[] array,
                       int pos)

Reads and decompresses an integer value from the specified byte array.

Parameters:

array - array

pos - position to parse

Returns:

decompressed value

size

public static int size(byte[] array)

Returns the length of the specified array, stored in the first four bytes.

Parameters:

array - array to be evaluated

Returns:

array length

len

public static int len(byte[] array,
                      int val)

Returns integer length.

Parameters:

array - array

val - integer value

Returns:

value length

size

public static void size(byte[] array,
                        int len)

Writes the specified length in the first bytes of the specified array.

Parameters:

array - array

len - new length

len

public static int len(int v)

Returns the compressed length of the specified value.

Parameters:

v - integer value

Returns:

value length