/*
* 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.algebra.table ;
import java.util.ArrayList ;
import java.util.Iterator ;
import java.util.List ;
import com.hp.hpl.jena.sparql.algebra.Algebra ;
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.QueryIterNullIterator ;
import com.hp.hpl.jena.sparql.engine.iterator.QueryIterPlainWrapper ;
import com.hp.hpl.jena.sparql.expr.ExprList ;
public class TableN extends TableBase {
protected List<Binding> rows = new ArrayList<Binding>() ;
protected List<Var> vars = new ArrayList<Var>() ;
public TableN() {}
public TableN(List<Var> vars) {
if ( vars != null )
this.vars = vars ;
}
public TableN(QueryIterator qIter) {
materialize(qIter) ;
}
protected TableN(List<Var> variables, List<Binding> rows) {
this.vars = variables ;
this.rows = rows ;
}
private void materialize(QueryIterator qIter) {
while (qIter.hasNext()) {
Binding binding = qIter.nextBinding() ;
addBinding(binding) ;
}
qIter.close() ;
}
@Override
public void addBinding(Binding binding) {
for (Iterator<Var> names = binding.vars(); names.hasNext();) {
Var v = names.next() ;
if ( !vars.contains(v) )
vars.add(v) ;
}
rows.add(binding) ;
}
@Override
public int size() {
return rows.size() ;
}
@Override
public boolean isEmpty() {
return rows.isEmpty() ;
}
// Note - this table is the RIGHT table, and takes a LEFT binding.
@Override
public QueryIterator matchRightLeft(Binding bindingLeft, boolean includeOnNoMatch, ExprList conditions,
ExecutionContext execContext) {
List<Binding> out = new ArrayList<Binding>() ;
for (Iterator<Binding> iter = rows.iterator(); iter.hasNext();) {
Binding bindingRight = iter.next() ;
Binding r = Algebra.merge(bindingLeft, bindingRight) ;
if ( r == null )
continue ;
// This does the conditional part. Theta-join.
if ( conditions == null || conditions.isSatisfied(r, execContext) )
out.add(r) ;
}
if ( out.size() == 0 && includeOnNoMatch )
out.add(bindingLeft) ;
if ( out.size() == 0 )
return QueryIterNullIterator.create(execContext) ;
return new QueryIterPlainWrapper(out.iterator(), execContext) ;
}
@Override
public Iterator<Binding> rows() {
return rows.iterator() ;
}
@Override
public QueryIterator iterator(ExecutionContext execCxt) {
return new QueryIterPlainWrapper(rows.iterator(), execCxt) ;
}
@Override
public void closeTable() {
rows = null ;
// Don't clear the vars in case code later asks for the variables.
}
@Override
public List<String> getVarNames() {
return Var.varNames(vars) ;
}
@Override
public List<Var> getVars() {
return vars ;
}
}