com.bigdata.rdf.internal

Class IVUnicode

java.lang.Object

com.bigdata.rdf.internal.IVUnicode

public class IVUnicode
extends Object

Utility class supporting IVs having inline Unicode data.

IVs must be able to report their correct mutual order. This means that the Java String must be given the same order as the encoded Unicode representation. Since we must include the #of bytes in the IV representation, this means that we wind up with a length prefix followed by some representation of the character data. This can not be consistent with the code point ordering imposed by String.compareTo(String). Therefore, the IVUnicode.IVUnicodeComparator is used to make the ordering over the String data consistent with the encoded representation of that data.

Note: This is not the only way to solve the problem. We could also have generated the encoded representation from any IV having inline Unicode data each time we need to compare two IVs, but that could turn into a lot of overhead.

Note: This does not attempt to make the Unicode representation "tight" and is not intended to handle very large Unicode strings. Large Unicode data in the statement indices causes them to bloat and has a negative impact on the overall system performance. The use case for inline Unicode data is when the data are small enough that they are worth inserting into the statement indices rather than indirecting through the TERM2ID/ID2TERM indices. Large RDF Values should always be inserted into the BLOBS index which is designed for that purpose.

Version:

$Id$ TODO This is directly persisting char[] data. Is that portable?

Author:

Bryan Thompson

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	IVUnicode.IVUnicodeComparator Class imposes the natural ordering of the encoded Unicode representation for an IV having inline Unicode data on Java Strings.

Constructor Summary

Constructors

Constructor and Description
IVUnicode()

Method Summary

Methods

Modifier and Type	Method and Description
static int	byteLengthUnicode(String s) Return the byte length of the serialized representation of a unicode string.
static byte[]	encode1(String s) Encode a Unicode string.

Methods inherited from class java.lang.Object

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

Constructor Detail

IVUnicode

public IVUnicode()

Method Detail

encode1

public static byte[] encode1(String s)

Encode a Unicode string.

Parameters:

s - The string.

Returns:

The encoded byte[].

byteLengthUnicode

public static int byteLengthUnicode(String s)

Return the byte length of the serialized representation of a unicode string.

Parameters:

s - The string.

Returns:

Its byte length.