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

 package org.galagosearch.core.retrieval.structured;

 import java.io.IOException;

 import org.galagosearch.tupleflow.Parameters;

 /**

  * <p>Implements the #inside operator.  The #inside operator is usually implicit

  * in the query language, where <tt>a.b</tt> is equivalent to <tt>#inside(a b)</tt>.

  * This is usually used to find terms that occur in fields.  For example,

  * <tt>#1(bruce croft).author</tt>, which finds instances of "bruce croft" occurring

  * in the author field of a document.</p>

  *

  * @author trevor

  */

 public class ExtentInsideIterator extends ExtentConjunctionIterator {

     ExtentIterator innerIterator;

     ExtentIterator outerIterator;

     /**

      * <p>Constructs an #inside instance.  For <tt>#inside(a b)</tt>, this

      * produces an extent whenever <tt>a</tt> is found inside <tt>b</tt>.</p>

      *

      * <p>For example, in the expression <tt>#inside(#1(white house) #extents:title())</tt>,

      * <tt>#1(white house)</tt> is the inner iterator and <tt>#extents:title()</tt>

      * is the outer iterator.  Whenever <tt>#1(white house)</tt> is found in the title of

      * a document, this is a match.  The extent for <tt>#1(white house)</tt> is returned

      * (not the extent for <tt>#extents:title()</tt> that surrounds it).</tt>

      *

      * @param parameters extra parameters, not used for anything.

      * @param innerIterator The source of extents that must be inside.

      * @param outerIterator The source of extents that must contain the inner extents.

      * @throws java.io.IOException

      */

     public ExtentInsideIterator(Parameters parameters,

             ExtentIterator innerIterator,

             ExtentIterator outerIterator) throws IOException {

         super(new ExtentIterator[] { innerIterator, outerIterator });

         this.innerIterator = innerIterator;

         this.outerIterator = outerIterator;

         findDocument();

     }

     /**

      * This method is called whenever the ExtentConjunctionIterator has verified

      * that both the inner and outer iterators match this document.  This method's job

      * is to find all matchin extents within the document, if they exist.

      */

     public void loadExtents() {

         ExtentArrayIterator inner = new ExtentArrayIterator(innerIterator.extents());

         ExtentArrayIterator outer = new ExtentArrayIterator(outerIterator.extents());

         while (!inner.isDone() && !outer.isDone()) {

             if (outer.current().contains(inner.current())) {

                 extents.add(inner.current());

                 inner.next();

             } else if (outer.current().end <= inner.current().begin) {

                 outer.next();

             } else {

                 inner.next();

             }

         }

     }

 }