/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Jan 6, 2008
*/
package com.bigdata.rdf.lexicon;
/**
* This interface defines the signed byte values indicating the type of a term
* in the term index. The purpose of this is to partition the term:id index into
* disjoint key ranges where the order of the terms in each of those partitions
* is well defined. I.e., URIs are in one key range and the total order over the
* URIs is well defined. The literals are broken down into a key range
* corresponding to the plain literals, the language type literals, and the data
* type literals (which is further broken down by the data type in order to
* produce well-defined total orders).
* <p>
* Note: when these signed bytes get encoded as unsigned bytes in a key their
* values change. For example, 2 becomes 130.
*
* @see ITermIdCodes, defines bit masks that are applied to the low bits of the
* assigned term identifiers and which indicate directly (without
* consulting the term index) whether a term is a URI, Literal, BNode, or
* Statement.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
public interface ITermIndexCodes {
/** indicates a URI. */
final public static byte TERM_CODE_URI = 0x01;
/** indicates a plain literal. */
final public static byte TERM_CODE_LIT = 0x02;
/** indicates a literal with a language code. */
final public static byte TERM_CODE_LCL = 0x03;
/** indicates a literal with a data type URI. */
final public static byte TERM_CODE_DTL = 0x04;
/** indicates a blank node. */
final public static byte TERM_CODE_BND = 0x05;
// /**
// * Indicates a statement identifier (used for statements about statements
// * where the statement identifier is used in any of the subject, predicate,
// * or object positions).
// * <p>
// * Note: Statement identifiers are assigned the highest code so that they
// * will be processed last when doing an ordered write of terms on the terms
// * index. This allows us to ensure that the component term identifiers in
// * the statement have been resolved before the statement itself is written
// * into the terms index.
// */
// final public static byte TERM_CODE_STMT = 0x06;
// /**
// * @deprecated This is a place holder for a namespace for an alternative
// * coding of datatype literal keys.
// */
// final public static byte TERM_CODE_DTL2 = 0x07;
}