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Lucene example source code file (ReqExclScorer.java)

This example Lucene source code file (ReqExclScorer.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

docidsetiterator, io, ioexception, ioexception, no_more_docs, no_more_docs, override, override, reqexclscorer, reqexclscorer, scorer

The Lucene ReqExclScorer.java source code

package org.apache.lucene.search;

/**
 * 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;


/** A Scorer for queries with a required subscorer
 * and an excluding (prohibited) sub DocIdSetIterator.
 * <br>
 * This <code>Scorer implements {@link Scorer#skipTo(int)},
 * and it uses the skipTo() on the given scorers.
 */
class ReqExclScorer extends Scorer {
  private Scorer reqScorer;
  private DocIdSetIterator exclDisi;
  private int doc = -1;

  /** Construct a <code>ReqExclScorer.
   * @param reqScorer The scorer that must match, except where
   * @param exclDisi indicates exclusion.
   */
  public ReqExclScorer(Scorer reqScorer, DocIdSetIterator exclDisi) {
    super(reqScorer.weight);
    this.reqScorer = reqScorer;
    this.exclDisi = exclDisi;
  }

  @Override
  public int nextDoc() throws IOException {
    if (reqScorer == null) {
      return doc;
    }
    doc = reqScorer.nextDoc();
    if (doc == NO_MORE_DOCS) {
      reqScorer = null; // exhausted, nothing left
      return doc;
    }
    if (exclDisi == null) {
      return doc;
    }
    return doc = toNonExcluded();
  }
  
  /** Advance to non excluded doc.
   * <br>On entry:
   * <ul>
   * <li>reqScorer != null,
   * <li>exclScorer != null,
   * <li>reqScorer was advanced once via next() or skipTo()
   *      and reqScorer.doc() may still be excluded.
   * </ul>
   * Advances reqScorer a non excluded required doc, if any.
   * @return true iff there is a non excluded required doc.
   */
  private int toNonExcluded() throws IOException {
    int exclDoc = exclDisi.docID();
    int reqDoc = reqScorer.docID(); // may be excluded
    do {  
      if (reqDoc < exclDoc) {
        return reqDoc; // reqScorer advanced to before exclScorer, ie. not excluded
      } else if (reqDoc > exclDoc) {
        exclDoc = exclDisi.advance(reqDoc);
        if (exclDoc == NO_MORE_DOCS) {
          exclDisi = null; // exhausted, no more exclusions
          return reqDoc;
        }
        if (exclDoc > reqDoc) {
          return reqDoc; // not excluded
        }
      }
    } while ((reqDoc = reqScorer.nextDoc()) != NO_MORE_DOCS);
    reqScorer = null; // exhausted, nothing left
    return NO_MORE_DOCS;
  }

  @Override
  public int docID() {
    return doc;
  }

  /** Returns the score of the current document matching the query.
   * Initially invalid, until {@link #nextDoc()} is called the first time.
   * @return The score of the required scorer.
   */
  @Override
  public float score() throws IOException {
    return reqScorer.score(); // reqScorer may be null when next() or skipTo() already return false
  }
  
  @Override
  public int advance(int target) throws IOException {
    if (reqScorer == null) {
      return doc = NO_MORE_DOCS;
    }
    if (exclDisi == null) {
      return doc = reqScorer.advance(target);
    }
    if (reqScorer.advance(target) == NO_MORE_DOCS) {
      reqScorer = null;
      return doc = NO_MORE_DOCS;
    }
    return doc = toNonExcluded();
  }
}

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



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