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Lucene example source code file (Spans.java)

This example Lucene source code file (Spans.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

collection, collection, io, ioexception, ioexception, spans, spans, util

The Lucene Spans.java source code

package org.apache.lucene.search.spans;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;
import java.util.Collection;

/** Expert: an enumeration of span matches.  Used to implement span searching.
 * Each span represents a range of term positions within a document.  Matches
 * are enumerated in order, by increasing document number, within that by
 * increasing start position and finally by increasing end position. */
public abstract class Spans {
  /** Move to the next match, returning true iff any such exists. */
  public abstract boolean next() throws IOException;

  /** Skips to the first match beyond the current, whose document number is
   * greater than or equal to <i>target. 

Returns true iff there is such * a match. <p>Behaves as if written:

   *   boolean skipTo(int target) {
   *     do {
   *       if (!next())
   * 	     return false;
   *     } while (target > doc());
   *     return true;
   *   }
   * </pre>
   * Most implementations are considerably more efficient than that.
   */
  public abstract boolean skipTo(int target) throws IOException;

  /** Returns the document number of the current match.  Initially invalid. */
  public abstract int doc();

  /** Returns the start position of the current match.  Initially invalid. */
  public abstract int start();

  /** Returns the end position of the current match.  Initially invalid. */
  public abstract int end();
  
  /**
   * Returns the payload data for the current span.
   * This is invalid until {@link #next()} is called for
   * the first time.
   * This method must not be called more than once after each call
   * of {@link #next()}. However, most payloads are loaded lazily,
   * so if the payload data for the current position is not needed,
   * this method may not be called at all for performance reasons. An ordered
   * SpanQuery does not lazy load, so if you have payloads in your index and
   * you do not want ordered SpanNearQuerys to collect payloads, you can
   * disable collection with a constructor option.<br>
   * <br>
    * Note that the return type is a collection, thus the ordering should not be relied upon.
    * <br/>
   * @lucene.experimental
   *
   * @return a List of byte arrays containing the data of this payload, otherwise null if isPayloadAvailable is false
   * @throws java.io.IOException
    */
  // TODO: Remove warning after API has been finalized
  public abstract Collection<byte[]> getPayload() throws IOException;

  /**
   * Checks if a payload can be loaded at this position.
   * <p/>
   * Payloads can only be loaded once per call to
   * {@link #next()}.
   *
   * @return true if there is a payload available at this position that can be loaded
   */
  public abstract boolean isPayloadAvailable();

}

Other Lucene examples (source code examples)

Here is a short list of links related to this Lucene Spans.java source code file:



my book on functional programming

 

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