/*
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
*/
package com.bigdata.rdf.internal.constraints;
import java.util.Map;
import org.openrdf.model.Literal;
import org.openrdf.query.algebra.evaluation.util.QueryEvaluationUtil;
import com.bigdata.bop.BOp;
import com.bigdata.bop.IBindingSet;
import com.bigdata.bop.IValueExpression;
import com.bigdata.rdf.error.SparqlTypeErrorException;
import com.bigdata.rdf.internal.IV;
import com.bigdata.rdf.internal.NotMaterializedException;
import com.bigdata.rdf.model.BigdataValue;
/**
* Implements the <a
* href="http://www.w3.org/TR/sparql11-query/#func-langMatches" >langMatches</a>
* SPARQL operator.
*
* @see http://www.w3.org/TR/sparql11-query/#func-langMatches
* @see http://www.ietf.org/rfc/rfc4647.txt
*/
public class LangMatchesBOp extends XSDBooleanIVValueExpression
implements INeedsMaterialization {
/**
*
*/
private static final long serialVersionUID = 5910711647357240974L;
/**
*
* @param tag
* The language tag.
* @param range
* The language range (allows "*", a language range such as "EN"
* or "DE", or an extended language range such as "de-DE" or
* "de-Latn-DE").
*
* @see http://www.ietf.org/rfc/rfc4647.txt
*/
@SuppressWarnings("rawtypes")
public LangMatchesBOp(
final IValueExpression<? extends IV> tag,
final IValueExpression<? extends IV> range) {
this(new BOp[] { tag, range }, BOp.NOANNS);
}
/**
* Required shallow copy constructor.
*/
public LangMatchesBOp(final BOp[] args, final Map<String, Object> anns) {
super(args, anns);
if (args.length != 2 || args[0] == null || args[1] == null)
throw new IllegalArgumentException();
}
/**
* Constructor required for {@link com.bigdata.bop.BOpUtility#deepCopy(FilterNode)}.
*/
public LangMatchesBOp(final LangMatchesBOp op) {
super(op);
}
@Override
protected boolean accept(final IBindingSet bs) {
final IV<?, ?> tag = get(0).get(bs);
// not yet bound
if (tag == null)
throw new SparqlTypeErrorException();
final IV<?, ?> range = get(1).get(bs);
// not yet bound
if (range == null)
throw new SparqlTypeErrorException();
// if (log.isDebugEnabled()) {
// log.debug(tag);
// log.debug(range);
// }
final BigdataValue tagVal = tag.getValue();
// not yet materialized
if (tagVal == null)
throw new NotMaterializedException();
if (!QueryEvaluationUtil.isSimpleLiteral(tagVal))
throw new SparqlTypeErrorException();
final BigdataValue rangeVal = range.getValue();
// not yet materialized
if (rangeVal == null)
throw new NotMaterializedException();
if (!QueryEvaluationUtil.isSimpleLiteral(rangeVal))
throw new SparqlTypeErrorException();
// if (log.isDebugEnabled()) {
// log.debug(tagVal);
// log.debug(rangeVal);
// }
final String langTag = ((Literal) tagVal).getLabel();
final String langRange = ((Literal) rangeVal).getLabel();
boolean result = false;
if (langRange.equals("*")) {
// Note: Must have a language tag to match.
result = langTag.length() > 0;
} else if (langTag.length() == langRange.length()) {
// Same length, same characters (case insensitive).
result = langTag.equalsIgnoreCase(langRange);
} else if (langTag.length() > langRange.length()) {
/*
* Check if the range is a prefix of the tag. If the range is longer
* the match must terminate on a "-" boundary in the language range.
*/
final String prefix = langTag.substring(0, langRange.length());
result = prefix.equalsIgnoreCase(langRange)
&& langTag.charAt(langRange.length()) == '-';
}
return result;
}
/**
* This bop can only work with materialized terms.
*/
@Override
public Requirement getRequirement() {
return INeedsMaterialization.Requirement.ALWAYS;
}
}