com.bigdata.rdf.model.StatementEnum Maven / Gradle / Ivy
/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
[email protected]
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 Oct 19, 2007
*/
package com.bigdata.rdf.model;
/**
* The basic statement types are: axioms, explicit, inferred.
*
* @author Bryan Thompson
* @version $Id$
*/
public enum StatementEnum {
/**
* A statement that was inserted into the database explicitly by the
* application.
*/
Explicit((byte) 0),
/**
* Something that is directly entailed by the appropriate model theory.
*/
Axiom((byte) 1),
/**
* A statement that was inferred from the explicit statements by the
* appropriate model theory.
*/
Inferred((byte) 2),
/**
* An explicit statement that was deleted but is being maintained in the
* statement indices for history.
*/
History((byte) 3);
private final byte code;
private StatementEnum(final byte code) {
this.code = code;
}
public byte code() {
return code;
}
/**
* Max returns the value that is first in the total order
*
* - Explicit
* - Axiom
* - Inferred
* - Deleted
*
* @param a
* @param b
* @return
*/
static public StatementEnum max(final StatementEnum a, final StatementEnum b) {
if (a.code < b.code) {
return a;
} else {
return b;
}
}
/**
* Decode a byte into a {@link StatementEnum}.
*
* Note: The override bit is masked off during this operation.
*
* @param b
* The byte.
*
* @return The {@link StatementEnum} value.
*/
static public StatementEnum decode(final byte b) {
switch (b & ~MASK_OVERRIDE & ~MASK_USER_FLAG) {
case 0: return Explicit;
case 1: return Axiom;
case 2: return Inferred;
case 3: return History;
default:
throw new RuntimeException("Unexpected byte: " + b);
}
}
// static public StatementEnum deserialize(DataInputBuffer in) {
//
// try {
//
// return decode(in.readByte());
//
// } catch(IOException ex) {
//
// throw new UnsupportedOperationException();
//
// }
//
// }
static public StatementEnum deserialize(final byte[] val) {
if (val.length != 1) {
throw new RuntimeException(
"Expecting one byte, not " + val.length);
}
return decode(val[0]);
}
public byte[] serialize() {
return new byte[]{code};
}
/**
* A bit mask used to isolate the bit that indicates that the existing
* statement type should be overridden thereby allowing the downgrade of a
* statement from explicit to inferred.
*/
public static final int MASK_OVERRIDE = 0x1 << 3;
/**
* A user bit mask used by applications to flag statements.
*/
public static final int MASK_USER_FLAG = 0x1 << 2;
/**
* Return true iff the user bit is set.
*
* @param b
* The byte.
*/
public static boolean isUserFlag(final byte b) {
return (b & StatementEnum.MASK_USER_FLAG) != 0;
}
/**
* Return true iff the override bit is set.
*
* @param b
* The byte.
*/
public static boolean isOverride(final byte b) {
return (b & StatementEnum.MASK_OVERRIDE) != 0;
}
}