DocHit.java

package org.cdlib.xtf.textEngine;


/**
 * Copyright (c) 2004, Regents of the University of California
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - Neither the name of the University of California nor the names of its
 *   contributors may be used to endorse or promote products derived from this
 *   software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.FieldDoc;
import org.cdlib.xtf.util.AttribList;

/**
 * Represents a query hit at the document level. May contain {@link Snippet}s
 * if those were requested.
 *
 * @author Martin Haye
 */
public abstract class DocHit extends FieldDoc 
{
  /**
   * Construct a document hit. Package-private because these should only
   * be constructed inside the text engine.
   *
   * @param docNum    Lucene ID for the document info chunk
   * @param score     Score for this hit
   */
  DocHit(int docNum, float score) {
    super(docNum, score);
  }

  /**
   * Retrieve the original file path as recorded in the index (if any.)
   */
  public abstract String filePath();

  /**
   * Retrieve this document's record number within the main file, or zero
   * if this is the only record.
   */
  public abstract int recordNum();
  
  /**
   * Retrieve this document's subdocument name, or null if there is
   * no subdocument (the default).
   */
  public abstract String subDocument();

  /**
   * Retrieve a list of all meta-data name/value pairs associated with this
   * document.
   */
  public abstract AttribList metaData();

  /** Return the total number of snippets found for this document (not the
   *  number actually returned, which is limited by the max # of snippets
   *  specified in the query.)
   */
  public abstract int totalSnippets();

  /**
   * Return the number of snippets available (limited by the max # specified
   * in the original query.)
   */
  public abstract int nSnippets();

  /**
   * Retrieve the specified snippet. In general, crossQuery will set getText
   * to 'true', while dynaXML may set it either way, depending on whether
   * the document result formatter stylesheet references the <snippet>
   * elements in the SearchTree. It's always safe, but not quite as
   * efficient, to assume 'true'.
   *
   * @param hitNum    0..nSnippets()
   * @param getText   true to fetch the snippet text in context, false to
   *                  optionally skip that work and only fetch the rank,
   *                  score, etc.
   *
   */
  public abstract Snippet snippet(int hitNum, boolean getText);

  /**
   * Get an explanation of this document's score. Only available if
   * requested at query time.
   */
  public Explanation explanation() {
    return null;
  }
} // class DocHit