/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hp.hpl.jena.sparql.expr;
import java.security.MessageDigest ;
import java.security.NoSuchAlgorithmException ;
import org.apache.jena.atlas.lib.Bytes ;
import com.hp.hpl.jena.datatypes.xsd.XSDDatatype ;
import com.hp.hpl.jena.graph.Node ;
import com.hp.hpl.jena.sparql.ARQInternalErrorException ;
public abstract class ExprDigest extends ExprFunction1
{
private final String digestName ;
private MessageDigest digestCache ;
public ExprDigest(Expr expr, String symbol, String digestName)
{
super(expr, symbol) ;
this.digestName = digestName ;
try
{
digestCache = MessageDigest.getInstance(digestName) ;
} catch (NoSuchAlgorithmException e)
{
throw new ARQInternalErrorException("Digest not provided in this Java system: "+digestName) ;
}
}
// Each digest expr function is unique
// Pool needs to be static and per-digest-type
// private Pool<MessageDigest> pool = PoolSync.create(new PoolBase<MessageDigest>()) ;
// private MessageDigest getDigest()
// {
// MessageDigest md = pool.get() ;
// if ( md == null )
// {
// synchronized (pool)
// {
// md = pool.get() ;
// if ( md == null )
// {
// md = createDigest() ;
// pool.put(md) ;
// }
// }
// }
// return md ;
// }
private MessageDigest getDigest()
{
if ( digestCache != null )
{
MessageDigest digest2 = null ;
try {
digest2 = (MessageDigest)digestCache.clone() ;
return digest2 ;
} catch (CloneNotSupportedException ex)
{
// Can't clone - remove cache copy.
digestCache = null ;
}
}
return createDigest() ;
}
private MessageDigest createDigest()
{
try { return MessageDigest.getInstance(digestName) ; }
catch (Exception ex2) { throw new ARQInternalErrorException(ex2) ; }
}
NodeValue lastSeen = null ;
NodeValue lastCalc = null ;
@Override
public NodeValue eval(NodeValue v)
{
if ( lastSeen != null && lastSeen.equals(v) )
return lastCalc ;
Node n = v.asNode() ;
if ( ! n.isLiteral() )
throw new ExprEvalException("Not a literal: "+v) ;
if ( n.getLiteralLanguage() != null && ! n.getLiteralLanguage().equals("") )
throw new ExprEvalException("Can't make a digest of an RDF term with a language tag") ;
// Literal, no language tag.
if ( n.getLiteralDatatype() != null && ! XSDDatatype.XSDstring.equals(n.getLiteralDatatype()) )
throw new ExprEvalException("Not a simple literal nor an XSD string") ;
try {
MessageDigest digest = getDigest() ;
String x = n.getLiteralLexicalForm() ;
byte b[] = x.getBytes("UTF-8") ;
byte d[] = digest.digest(b) ;
String y = Bytes.asHexLC(d) ;
NodeValue result = NodeValue.makeString(y) ;
// Cache
lastSeen = v ;
lastCalc = result ;
return result ;
} catch (Exception ex2) { throw new ARQInternalErrorException(ex2) ; }
}
}