/*
* 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 org.apache.jena.sparql.pfunction.library;
import java.util.ArrayList ;
import java.util.Collection ;
import java.util.List ;
import org.apache.jena.graph.Graph ;
import org.apache.jena.graph.Node ;
import org.apache.jena.sparql.core.Var ;
import org.apache.jena.sparql.engine.ExecutionContext ;
import org.apache.jena.sparql.engine.QueryIterator ;
import org.apache.jena.sparql.engine.binding.Binding ;
import org.apache.jena.sparql.engine.binding.BindingFactory ;
import org.apache.jena.sparql.engine.binding.BindingMap ;
import org.apache.jena.sparql.engine.iterator.QueryIterPlainWrapper ;
import org.apache.jena.sparql.expr.ExprEvalException ;
import org.apache.jena.sparql.pfunction.PropFuncArg ;
import org.apache.jena.sparql.util.IterLib ;
import org.apache.jena.sparql.util.NodeFactoryExtra ;
import org.apache.jena.sparql.util.graph.GNode ;
import org.apache.jena.sparql.util.graph.GraphList ;
/** List membership with index : property function to access list using index
* Usage: ?list :listIndex (?index ?member) */
public class listIndex extends ListBaseList
{
@Override
protected QueryIterator execObjectList(Binding binding, Var listVar, Node predicate, List<Node> objectArgs,
ExecutionContext execCxt)
{
// subject a variable.
if ( objectArgs.size() != 2 )
throw new ExprEvalException("ListIndex : object not a list of length 2") ;
Node indexNode = objectArgs.get(0) ;
Node memberNode = objectArgs.get(1) ;
final Collection<Node> x ;
if ( ! Var.isVar(memberNode) )
// If memberNode is defined, find lists containing it.
x = GraphList.listFromMember(new GNode(execCxt.getActiveGraph(), memberNode)) ;
else
// Hard. Subject unbound, no fixed member. Find every list and use BFI.
x = GraphList.findAllLists(execCxt.getActiveGraph()) ;
return super.allLists(binding, x, listVar, predicate, new PropFuncArg(objectArgs, null), execCxt) ;
}
@Override
protected QueryIterator execOneList(Binding binding,
Node listNode, Node predicate, List<Node> objectArgs,
ExecutionContext execCxt)
{
if ( Var.isVar(listNode) )
throw new ExprEvalException("ListIndex : subject not a list or variable bound to a list") ;
if ( objectArgs.size() != 2 )
throw new ExprEvalException("ListIndex : object not a list of length 2") ;
Node indexNode = objectArgs.get(0) ;
Node memberNode = objectArgs.get(1) ;
Graph graph = execCxt.getActiveGraph() ;
if ( Var.isVar(indexNode) && ! Var.isVar(memberNode) )
return findIndex(graph, binding, listNode, Var.alloc(indexNode), memberNode, execCxt) ;
if ( ! Var.isVar(indexNode) && Var.isVar(memberNode) )
return getByIndex(graph, binding, listNode, indexNode, Var.alloc(memberNode), execCxt) ;
if ( ! Var.isVar(indexNode) && ! Var.isVar(memberNode) )
return testSlotValue(graph, binding, listNode, indexNode, memberNode, execCxt) ;
return findIndexMember(graph, binding, listNode, Var.alloc(indexNode), Var.alloc(memberNode), execCxt) ;
}
private static QueryIterator getByIndex(Graph graph, Binding binding,
Node listNode, Node indexNode, Var varMember,
ExecutionContext execCxt)
{
int i = NodeFactoryExtra.nodeToInt(indexNode) ;
if ( i < 0 )
return IterLib.noResults(execCxt) ;
Node n = GraphList.get(new GNode(graph, listNode), i) ;
if ( n == null )
return IterLib.noResults(execCxt) ;
return IterLib.oneResult(binding, varMember, n, execCxt) ;
}
private static QueryIterator testSlotValue(Graph graph, Binding binding,
Node listNode, Node indexNode, Node memberNode,
ExecutionContext execCxt)
{
int i = NodeFactoryExtra.nodeToInt(indexNode) ;
if ( i < 0 )
return IterLib.noResults(execCxt) ;
Node n = GraphList.get(new GNode(graph, listNode), i) ;
if ( n == null )
return IterLib.noResults(execCxt) ;
if ( n.equals(memberNode) )
return IterLib.result(binding, execCxt) ;
else
return IterLib.noResults(execCxt) ;
}
private static QueryIterator findIndex(Graph graph, Binding binding,
Node listNode, Var var, Node member,
ExecutionContext execCxt)
{
// Find index of member.
int i = GraphList.index(new GNode(graph, listNode), member) ;
if ( i < 0 )
return IterLib.noResults(execCxt) ;
Node idx = NodeFactoryExtra.intToNode(i) ;
return IterLib.oneResult(binding, var, idx, execCxt) ;
}
private static QueryIterator findIndexMember(Graph graph, Binding binding,
Node listNode, Var varIndex, Var varMember,
ExecutionContext execCxt)
{
// Iterate over list
List<Node> members = GraphList.members(new GNode(graph, listNode)) ;
List<Binding> bindings = new ArrayList<>() ;
for ( int i = 0 ; i < members.size() ; i++ )
{
Node idx = NodeFactoryExtra.intToNode(i) ;
Node member = members.get(i) ;
BindingMap b = BindingFactory.create(binding) ;
b.add(varIndex, idx) ;
b.add(varMember, member) ;
bindings.add(b) ;
}
return new QueryIterPlainWrapper(bindings.iterator(), execCxt) ;
}
}