/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
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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 Aug 28, 2012
*/
package com.bigdata.rdf.sparql.ast;
/**
* Type-safe enumeration of the different ways in which we can evaluate a
* DESCRIBE query.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
*
* @see <a href="https://sourceforge.net/apps/trac/bigdata/ticket/578"> Concise
* Bounded Description </a>
*
* TODO This enumeration does not allow for inverse functional constraints.
* That extension can help with foaf data.
*/
public enum DescribeModeEnum {
/**
* The DESCRIBE is only the attributes and forward links.
*/
ForwardOneStep(true/* forward */, false/* reverse */,
false/* reifiedStatements */, false/* recursive */),
/**
* The DESCRIBE is the symmetric one-step neighborhood of the resource
* (attributes, forward links, and backward links).
*/
SymmetricOneStep(true/* forward */, true/* reverse */,
false/* reifiedStatements */, false/* recursive */),
/**
* Concise Bounded Description.
*
* <pre>
* Given a particular node (the starting node) in a particular RDF
* graph (the source graph), a subgraph of that particular graph,
* taken to comprise a concise bounded description of the resource
* denoted by the starting node, can be identified as follows:
*
* 1. Include in the subgraph all statements in the source graph
* where the subject of the statement is the starting node;
*
* 2. Recursively, for all statements identified in the subgraph
* thus far having a blank node object, include in the subgraph
* all statements in the source graph where the subject of the
* statement is the blank node in question and which are not
* already included in the subgraph.
*
* 3. Recursively, for all statements included in the subgraph
* thus far, for all reifications of each statement in the
* source graph, include the concise bounded description
* beginning from the rdf:Statement node of each reification.
*
* This results in a subgraph where the object nodes are either URI
* references, literals, or blank nodes not serving as the subject
* of any statement [not] in the [sub]graph.
* </pre>
*
* The text is square brackets is my own (presumed) correction to the
* definition of Concise Bounded Description and reflects the actual
* behavior of this mode.
*
* @see <a href="http://www.w3.org/Submission/CBD/"> CBD - Concise Bounded
* Description </a>
*/
CBD(true/* forward */, false/* reverse */, true/* reifiedStatements */,
true/* recursive */),
/**
* Symmetric Concise Bounded Description (SCBD).
*
* <pre>
* Specifically, given a particular node (the starting node) in a particular
* RDF graph (the source graph), a subgraph of that particular graph, taken
* to comprise a symmetric concise bounded description of the resource
* denoted by the starting node, can be identified as follows:
*
* 1. Include in the subgraph all statements in the source graph where the
* object of the statement is the starting node;
*
* 2. Recursively, for all statements identified in the subgraph thus far
* having a blank node subject not equal to the starting node, include in
* the subgraph all statements in the source graph where the object of the
* statement is the blank node in question and which are not already
* included in the subgraph.
*
* 3. Recursively, for all statements included in the subgraph thus far, for
* all reifications of each statement in the source graph, include the
* symmetric concise bounded description beginning from the rdf:Statement
* node of each reification.
*
* 4. Include in the subgraph the concise bounded description beginning from
* the starting node.
*
* This produces a subgraph that includes a concise bounded description,
* given the same starting point, but in addition, includes all inbound arc
* paths, up to but not beyond a URIref subject node.
* </pre>
*
* Note: Our evaluation actually proceeds in both the forward and reverse
* direction at the same time. However, this is an efficiency matter and has
* no effect on the semantics of the description.
*/
SCBD(true/* forward */, true/* reverse */, true/* reifiedStatements */,
true/* recursive */);
// /**
// * Concise Bounded Description without Reification.
// * <p>
// * This is the same as {@link #CBD} except that the source graph is NOT
// * probed for reifications of statements in the subgraph thus far (step 3).
// * This option is useful when reified statement models are not common in the
// * data and it avoids the overhead of testing for a reified statement model
// * for each statement in the subgraph.
// */
// CBDNR(true/* forward */, false/* reverse */, false/* reifiedStatements */,
// true/* recursive */),
// /**
// * Symmetric Concise Bounded Description without Reification.
// * <p>
// * This is the same as {@link #SCBD} except that the source graph is NOT
// * probed for reifications of statements in the subgraph thus far (step 3).
// * This option is useful when reified statement models are not common in the
// * data and it avoids the overhead of testing for a reified statement model
// * for each statement in the subgraph.
// */
// SCBDNR(true/* forward */, true/* reverse */, false/* reifiedStatements */,
// true/* recursive */);
private final boolean forward;
private final boolean reverse;
private final boolean reifiedStatements;
private final boolean recursive;
private DescribeModeEnum(final boolean forward, final boolean reverse,
final boolean reifiedStatements, final boolean recursive) {
this.forward = forward;
this.reverse = reverse;
this.reifiedStatements = reifiedStatements;
this.recursive = recursive;
}
/**
* Return <code>true</code> if the description includes the non-link
* attributes and forward links.
*/
public boolean isForward() {
return forward;
}
/**
* Return <code>true</code> if the description includes the reverse links.
*/
public boolean isReverse() {
return reverse;
}
/**
* Return <code>true</code> if the description includes the description of
* reified statements found in the description.
*/
public boolean isReifiedStatements() {
return reifiedStatements;
}
/**
* Return <code>true</code> if the description includes a recursive
* expansion.
*/
public boolean isRecursive() {
return recursive;
}
}