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

 package org.galagosearch.core.retrieval.structured;

 import java.io.IOException;

 import java.util.ArrayList;

 import org.galagosearch.core.util.ExtentArray;

 /**

  *

  * @author trevor

  */

 public abstract class ExtentConjunctionIterator extends ExtentIterator {

     protected ExtentIterator[] extentIterators;

     protected ExtentArray extents;

     protected int document;

     protected boolean done;

     public ExtentConjunctionIterator(ExtentIterator[] extIterators) {

         this.done = false;

         this.extentIterators = extIterators;

         this.extents = new ExtentArray();

     }

     public abstract void loadExtents();

     public void nextDocument() throws IOException {

         if (!done) {

             extentIterators[0].nextDocument();

             findDocument();

         }

     }

     public void findDocument() throws IOException {

         while (!done) {

             // find a document that might have some matches

             document = MoveIterators.moveAllToSameDocument(extentIterators);

             // if we're done, quit now

             if (document == Integer.MAX_VALUE) {

                 done = true;

                 break;

             }

             // try to load some extents (subclass does this)

             extents.reset();

             loadExtents();

             // were we successful? if so, quit, otherwise keep looking for documents

             if (extents.getPosition() > 0) {

                 break;

             }

             extentIterators[0].nextDocument();

         }

     }

     public ExtentArray extents() {

         return extents;

     }

     public int document() {

         return document;

     }

     public int count() {

         return extents().getPosition();

     }

     public boolean isDone() {

         return done;

     }

     public void reset() throws IOException {

         for (ExtentIterator iterator : extentIterators) {

             iterator.reset();

         }

         done = false;

         findDocument();

     }

 }