/*
* 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 com.hp.hpl.jena.graph.Graph ;
import com.hp.hpl.jena.graph.Node ;
import com.hp.hpl.jena.sparql.ARQInternalErrorException ;
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.util.IterLib ;
import com.hp.hpl.jena.sparql.util.NodeFactoryExtra ;
import com.hp.hpl.jena.sparql.util.graph.GNode ;
import com.hp.hpl.jena.sparql.util.graph.GraphList ;
/** List length : property function to get the length of a list. */
public class listLength extends ListBase1
{
@Override
public QueryIterator execOneList(Binding binding, Node listNode, Node predicate, Node length, ExecutionContext execCxt)
{
Graph graph = execCxt.getActiveGraph() ;
if ( Var.isVar(listNode) )
throw new ARQInternalErrorException("listLength: Subject is a variable") ;
// 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(length) )
return length(binding, graph, listNode, Var.alloc(length) , execCxt) ;
else
return verify(binding, graph, listNode, length, execCxt) ;
}
private QueryIterator length(Binding binding, Graph graph,
Node listNode, Var varLength,
ExecutionContext execCxt)
{
int x = GraphList.length(new GNode(graph, listNode)) ;
if ( x < 0 )
return IterLib.noResults(execCxt) ;
Node n = NodeFactoryExtra.intToNode(x) ;
return IterLib.oneResult(binding, varLength, n, execCxt) ;
}
private QueryIterator verify(Binding binding, Graph graph, Node listNode, Node length, ExecutionContext execCxt)
{
int x = GraphList.length(new GNode(graph, listNode)) ;
int len = NodeFactoryExtra.nodeToInt(length) ;
if ( x == len )
return IterLib.result(binding, execCxt) ;
return IterLib.noResults(execCxt) ;
}
@Override
protected QueryIterator execObjectBound(Binding binding, Var listVar, Node predicate, Node length,
ExecutionContext execCxt)
{
Graph graph = execCxt.getActiveGraph() ;
return length(binding, graph, listVar, Var.alloc(length) , execCxt) ;
}
}