// BSD License (http://www.galagosearch.org/license)

 package org.galagosearch.core.index;

 import java.io.IOException;

 import java.util.Map;

 import org.galagosearch.core.retrieval.query.Node;

 import org.galagosearch.core.retrieval.query.NodeType;

 import org.galagosearch.core.retrieval.structured.IndexIterator;

 /**

  * A StructuredIndexPart is an object that can create StructuredIterators that

  * can be used in query processing.  StructuredIndex creates many StructuredIndexPartReaders

  * and uses them to supply iterators to StructuredRetrieval.

  * 

  * Usually a StructuredIndexPartReader uses an IndexReader to retrieve data from disk,

  * then adds its own special logic to decode that data.

  * 

  * @author trevor

  */

 public interface StructuredIndexPartReader {

     /// Closes any underlying files used by this index part.

     public void close() throws IOException;

     /// Returns a list of node types that this index can provide.

     public Map<String, NodeType> getNodeTypes();

     /// Returns an iterator over the whole index.

     public IndexIterator getIterator() throws IOException;

     /// Returns an iterator corresponding to a query node from a StructuredQuery.

     public IndexIterator getIterator(Node node) throws IOException;

 }