/*
* 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.engine.main;
import org.apache.jena.sparql.core.BasicPattern ;
import org.apache.jena.sparql.engine.ExecutionContext ;
import org.apache.jena.sparql.engine.QueryIterator ;
/** Interface for execution of a basic graph pattern.
* A StageGenerator is registred in the context of an query
* execution to be found and called by the StageBuilder.
*
* The StageGenerator is called repeated for a basic graph pattern
* with each possible bindings unsed to instantiate variables
* where possible.
*
* Each call of a stage generator returns a QueryIterator
* of solutions to the pattern for each of the possibilities
* (bindings) from the input query iterator.
*
* Result bindings to a particular input binding should use that
* as their parent, to pick up the variable bounds for that
* particular input.
*
* @see StageBuilder
*/
public interface StageGenerator
{
public QueryIterator execute(BasicPattern pattern,
QueryIterator input,
ExecutionContext execCxt) ;
}