/*
* 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.tdb.solver;
import java.util.* ;
import org.apache.jena.atlas.logging.Log ;
import com.hp.hpl.jena.graph.Node ;
import com.hp.hpl.jena.sparql.core.Var ;
import com.hp.hpl.jena.sparql.engine.binding.Binding ;
import com.hp.hpl.jena.sparql.engine.binding.BindingBase ;
import com.hp.hpl.jena.tdb.lib.NodeFmtLib ;
import com.hp.hpl.jena.tdb.nodetable.NodeTable ;
import com.hp.hpl.jena.tdb.store.NodeId ;
/** Bind that delays turning a NodeId into a Node until explicitly needed by get() */
public class BindingTDB extends BindingBase
{
private final NodeTable nodeTable ;
private final BindingNodeId idBinding ;
private static final boolean caching = false ;
// Whether the cache is worthwhile is unclear - the NodeTable keeps a cache.
private final Map<Var,Node> cache = ( caching ? new HashMap<Var, Node>() : null ) ;
public BindingTDB(BindingNodeId idBinding, NodeTable nodeTable)
{
// BindingNodeId contains the bindings actually used copied down when created.
super(idBinding.getParentBinding()) ;
this.idBinding = idBinding ;
this.nodeTable = nodeTable ;
}
@Override
protected int size1() { return idBinding.size(); }
private List<Var> vars = null ;
/** Iterate over all the names of variables. */
@Override
protected Iterator<Var> vars1()
{
if ( vars == null )
vars = calcVars() ;
return vars.iterator() ;
}
private List<Var> calcVars()
{
List<Var> vars = new ArrayList<Var>(4) ;
// Only if not in parent.
// A (var/value) binding may have been copied down to record it's NodeId.
Binding b = idBinding.getParentBinding() ;
Iterator<Var> iter = idBinding.iterator() ;
for ( Var v : idBinding )
{
if ( b == null || ! b.contains(v) )
vars.add(v) ;
}
return vars ;
}
@Override
protected boolean isEmpty1()
{
return size1() == 0 ;
}
@Override
public boolean contains1(Var var)
{
return idBinding.containsKey(var) ;
}
public BindingNodeId getBindingId() { return idBinding ; }
public NodeId getNodeId(Var var)
{
NodeId id = idBinding.get(var) ;
if ( id != null )
return id ;
if ( parent == null )
return null ;
// Maybe in the parent.
if ( parent instanceof BindingTDB )
return ((BindingTDB)parent).getNodeId(var) ;
return null ;
}
@Override
public Node get1(Var var)
{
try {
Node n = cacheGet(var) ;
if ( n != null )
return n ;
NodeId id = idBinding.get(var) ;
if ( id == null )
return null ;
n = nodeTable.getNodeForNodeId(id) ;
// Update cache.
cachePut(var, n) ;
return n ;
} catch (Exception ex)
{
Log.fatal(this, String.format("get1(%s)", var), ex) ;
return null ;
}
}
private void cachePut(Var var, Node n)
{
if ( cache != null ) cache.put(var, n) ;
}
private Node cacheGet(Var var)
{
if ( cache == null ) return null ;
return cache.get(var) ;
}
@Override
protected void format(StringBuffer sbuff, Var var)
{
NodeId id = idBinding.get(var) ;
String extra = "" ;
if ( id != null )
extra = "/"+id ;
Node node = get(var) ;
String tmp = NodeFmtLib.displayStr(node) ;
sbuff.append("( ?"+var.getVarName()+extra+" = "+tmp+" )") ;
}
}