searcher.java

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package org.apache.lucene.search;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache Lucene" must not be used to endorse or promote products
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 * 5. Products derived from this software may not be called "Apache",
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import java.io.IOException;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.Term;

/** The abstract base class for search implementations.
  <p>Subclasses implement search over a single index, over multiple indices,
  and over indices on remote servers.
 */
public abstract class Searcher {

  /** Returns the documents matching <code>query</code>. */
  public final Hits search(Query query) throws IOException {
    return search(query, (Filter)null);
  }

  /** Returns the documents matching <code>query</code> and
    <code>filter</code>. */
  public Hits search(Query query, Filter filter) throws IOException {
    return new Hits(this, query, filter);
  }

  /** Lower-level search API.
   *
   * <p>{@link HitCollector#collect(int,float)} is called for every non-zero
   * scoring document.
   *
   * <p>Applications should only use this if they need <i>all</i> of the
   * matching documents.  The high-level search API ({@link
   * Searcher#search(Query)}) is usually more efficient, as it skips
   * non-high-scoring hits.  */
  public void search(Query query, HitCollector results)
    throws IOException {
    search(query, (Filter)null, results);
  }    

  /** Lower-level search API.
   *
   * <p>{@link HitCollector#collect(int,float)} is called for every non-zero
   * scoring document.
   *
   * <p>Applications should only use this if they need <i>all</i> of the
   * matching documents.  The high-level search API ({@link
   * Searcher#search(Query)}) is usually more efficient, as it skips
   * non-high-scoring hits.
   *
   * @param query to match documents
   * @param filter if non-null, a bitset used to eliminate some documents
   * @param results to receive hits
   */
  public abstract void search(Query query, Filter filter, HitCollector results)
    throws IOException;

  /** Frees resources associated with this Searcher. */
  abstract public void close() throws IOException;

  abstract int docFreq(Term term) throws IOException;
  abstract int maxDoc() throws IOException;
  abstract TopDocs search(Query query, Filter filter, int n)
       throws IOException;

  /** For use by {@link HitCollector} implementations. */
  public abstract Document doc(int i) throws IOException;
}