/*
* 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.util.IdentityHashMap ;
import java.util.List ;
import com.hp.hpl.jena.graph.Node ;
import com.hp.hpl.jena.sparql.ARQInternalErrorException ;
import com.hp.hpl.jena.sparql.engine.binding.Binding ;
import com.hp.hpl.jena.sparql.function.FunctionEnv ;
import com.hp.hpl.jena.sparql.util.LabelToNodeMap ;
import com.hp.hpl.jena.sparql.util.Symbol ;
public class E_BNode extends ExprFunctionN // 0 or one
{
private static final String symbol = "bnode" ;
private static final Symbol keyMap = Symbol.create("arq:internal:bNodeMappings") ;
public E_BNode() { this(null) ; }
public E_BNode(Expr expr)
{
// Expr maybe null for BNode()
super(symbol, expr) ;
}
// Not really a special form but we need access to
// the binding to use a key.
@Override
public NodeValue evalSpecial(Binding binding, FunctionEnv env)
{
Expr expr = null ;
if ( args.size() == 1 )
expr = getArg(1) ;
if ( expr == null )
return NodeValue.makeNode(Node.createAnon()) ;
NodeValue x = expr.eval(binding, env) ;
if ( ! x.isString() )
throw new ExprEvalException("Not a string: "+x) ;
Integer key = System.identityHashCode(binding) ;
// IdentityHashMap
// Normally bindings have structural equality (e.g. DISTINCT)
// we want identify as OpAssign/OpExtend mutates a binding to add new pairs.
@SuppressWarnings("unchecked")
IdentityHashMap<Binding, LabelToNodeMap> mapping = (IdentityHashMap<Binding, LabelToNodeMap>)env.getContext().get(keyMap) ;
if ( mapping == null )
{
mapping = new IdentityHashMap<Binding, LabelToNodeMap>() ;
env.getContext().set(keyMap, mapping) ;
}
LabelToNodeMap mapper = mapping.get(binding) ;
if ( mapper == null )
{
mapper = LabelToNodeMap.createBNodeMap() ;
mapping.put(binding, mapper) ;
}
Node bnode = mapper.asNode(x.getString()) ;
return NodeValue.makeNode(bnode) ;
}
@Override
protected NodeValue eval(List<NodeValue> args)
{ throw new ARQInternalErrorException() ; }
@Override
protected Expr copy(ExprList newArgs)
{
if ( newArgs.size() == 0 )
return new E_BNode() ;
else
return new E_BNode(newArgs.get(0)) ;
}
}