/*
* 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.pfunction.library;
import java.util.List ;
import com.hp.hpl.jena.graph.Node ;
import com.hp.hpl.jena.query.QueryBuildException ;
import com.hp.hpl.jena.query.QueryExecException ;
import com.hp.hpl.jena.sparql.core.Var ;
import com.hp.hpl.jena.sparql.engine.ExecutionContext ;
import com.hp.hpl.jena.sparql.engine.QueryIterator ;
import com.hp.hpl.jena.sparql.engine.binding.Binding ;
import com.hp.hpl.jena.sparql.engine.iterator.QueryIterExtendByVar ;
import com.hp.hpl.jena.sparql.engine.iterator.QueryIterYieldN ;
import com.hp.hpl.jena.sparql.pfunction.PropFuncArg ;
import com.hp.hpl.jena.sparql.util.graph.GNode ;
import com.hp.hpl.jena.sparql.util.graph.GraphList ;
/** List membership : property function implementation of list:member. */
public class listMember extends ListBase1
{
// Does not work for ... list:member ?x .
// See old execOneList
public listMember()
{ super() ; }
@Override
public void build(PropFuncArg argSubject, Node predicate, PropFuncArg argObject, ExecutionContext execCxt)
{
super.build(argSubject, predicate, argObject, execCxt) ;
if ( argObject.isList() && argObject.getArgList().size() != 0 )
throw new QueryBuildException("List arguments (object) to "+predicate.getURI()) ;
}
@Override
protected QueryIterator execOneList(Binding binding, Node listNode, Node predicate, Node member, ExecutionContext execCxt)
{
if ( Var.isVar(listNode) )
throw new QueryExecException("List : subject not a list or variable bound to a list") ;
// Case : arg 1 (the list) is bound and arg 2 not bound => generate possibilities
// Case : arg 1 is bound and arg 2 is bound => test for membership.
if ( Var.isVar(member) )
return members(binding, listNode, Var.alloc(member) , execCxt) ;
else
return verify(binding, listNode, member, execCxt) ;
}
@Override
protected QueryIterator execObjectBound(Binding binding, Var listVar, Node predicate, Node object,
ExecutionContext execCxt)
{
// Given a concrete node, find lists it's in
GNode gnode = new GNode(execCxt.getActiveGraph(), object) ;
List<Node> lists = GraphList.listFromMember(gnode) ;
return new QueryIterExtendByVar(binding, listVar, lists.iterator(), execCxt) ;
}
private QueryIterator members(Binding binding, Node listNode, Var itemVar, ExecutionContext execCxt)
{
List<Node> members = GraphList.members(new GNode(execCxt.getActiveGraph(), listNode)) ;
return new QueryIterExtendByVar(binding, itemVar, members.iterator(), execCxt) ;
}
private QueryIterator verify(Binding binding, Node listNode, Node member, ExecutionContext execCxt)
{
int count = GraphList.occurs(new GNode(execCxt.getActiveGraph(), listNode), member) ;
return new QueryIterYieldN(count, binding) ;
}
}