/**
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 Aug 18, 2010
*/
package com.bigdata.bop.paths;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.FutureTask;
import org.apache.log4j.Logger;
import com.bigdata.bop.BOp;
import com.bigdata.bop.BOpContext;
import com.bigdata.bop.HashMapAnnotations;
import com.bigdata.bop.IBindingSet;
import com.bigdata.bop.NV;
import com.bigdata.bop.PipelineOp;
import com.bigdata.bop.solutions.JVMDistinctBindingSetsOp;
import com.bigdata.rdf.sparql.ast.ArbitraryLengthPathNode.Annotations;
/**
* @see {@link ArbitraryLengthPathTask}
*/
public class ArbitraryLengthPathOp extends PipelineOp {
private static final Logger log = Logger.getLogger(ArbitraryLengthPathOp.class);
/**
*
*/
private static final long serialVersionUID = 1L;
public interface Annotations extends com.bigdata.bop.PipelineOp.Annotations {
/**
* The subquery representing the path between left and right.
*/
String SUBQUERY = Annotations.class.getName() + ".subquery";
/**
* The left term - can be a variable or a constant.
*/
String LEFT_TERM = Annotations.class.getName() + ".leftTerm";
/**
* The right term - can be a variable or a constant.
*/
String RIGHT_TERM = Annotations.class.getName() + ".rightTerm";
/**
* The left transitivity variable.
*/
String TRANSITIVITY_VAR_LEFT = Annotations.class.getName() + ".transitivityVarLeft";
/**
* The right transitivity variable.
*/
String TRANSITIVITY_VAR_RIGHT = Annotations.class.getName() + ".transitivityVarRight";
/**
* The lower bound on the number of rounds to run. Can be zero (0) or
* one (1). A lower bound of zero is a special kind of path - the
* Zero Length Path. A zero length path connects a vertex to itself
* (in graph parlance). In the context of arbitrary length paths it
* means we bind the input onto the output regardless of whether they
* are actually connected via the path or not.
*/
String LOWER_BOUND = Annotations.class.getName() + ".lowerBound";
/**
* The upper bound on the number of rounds to run.
*/
String UPPER_BOUND = Annotations.class.getName() + ".upperBound";
/**
* The vars projected into this ALP op.
*/
String PROJECT_IN_VARS = Annotations.class.getName() + ".projectInVars";
/**
* The initial capacity of the {@link ConcurrentHashMap} used to impose
* the distinct filter (required to avoid duplicates).
*
* @see #DEFAULT_INITIAL_CAPACITY
*/
String INITIAL_CAPACITY = HashMapAnnotations.class.getName()
+ ".initialCapacity";
int DEFAULT_INITIAL_CAPACITY = 16;
/**
* The load factor of the {@link ConcurrentHashMap} used to impose the
* distinct filter (required to avoid duplicates).
*
* @see #DEFAULT_LOAD_FACTOR
*/
String LOAD_FACTOR = HashMapAnnotations.class.getName() + ".loadFactor";
float DEFAULT_LOAD_FACTOR = .75f;
/**
* The middle term - can be a variable or a constant. Only used
* when edge var is present.
*/
String MIDDLE_TERM = Annotations.class.getName() + ".middleTerm";
/**
* The edge variable. This is an extension that allows the caller
* to understand how a node was visited (what was the edge that
* led to it). If set, this will allow in duplicate solutions in
* violation of the SPARQL spec (if a node can be reached by more than
* one path there will be one solution emitted per path). Used
* in conjunction with the middle term. If the middle term is a var,
* the edge var must not be the same var, since the middle var is
* used to calculate transitive closure.
*/
String EDGE_VAR = Annotations.class.getName() + ".edgeVar";
/**
* A list of intermediate variables (IVariables) used by the ALP op
* that should be dropped from the solutions after each round.
*/
String DROP_VARS = Annotations.class.getName() + ".dropVars";
}
/**
* Deep copy constructor.
*/
public ArbitraryLengthPathOp(final ArbitraryLengthPathOp op) {
super(op);
}
/**
* Shallow copy constructor.
*
* @param args
* @param annotations
*/
public ArbitraryLengthPathOp(final BOp[] args,
final Map<String, Object> annotations) {
super(args, annotations);
getRequiredProperty(Annotations.SUBQUERY);
getRequiredProperty(Annotations.LEFT_TERM);
getRequiredProperty(Annotations.RIGHT_TERM);
getRequiredProperty(Annotations.TRANSITIVITY_VAR_LEFT);
getRequiredProperty(Annotations.TRANSITIVITY_VAR_RIGHT);
getRequiredProperty(Annotations.LOWER_BOUND);
getRequiredProperty(Annotations.UPPER_BOUND);
getRequiredProperty(Annotations.PROJECT_IN_VARS);
getRequiredProperty(Annotations.DROP_VARS);
}
public ArbitraryLengthPathOp(final BOp[] args, NV... annotations) {
this(args, NV.asMap(annotations));
}
@Override
public FutureTask<Void> eval(final BOpContext<IBindingSet> context) {
return new FutureTask<Void>(new ArbitraryLengthPathTask(this, context));
}
}