content: 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 part and an optional part.
   * Delays skipTo() on the optional part until a score() is needed.
   * <br>
   * This <code>Scorer</code> implements {@link Scorer#skipTo(int)}.
   */
  class ReqOptSumScorer extends Scorer {
    /** The scorers passed from the constructor.
     * These are set to null as soon as their next() or skipTo() returns false.
     */
    private Scorer reqScorer;
    private Scorer optScorer;
  
    /** Construct a <code>ReqOptScorer</code>.
     * @param reqScorer The required scorer. This must match.
     * @param optScorer The optional scorer. This is used for scoring only.
     */
    public ReqOptSumScorer(
        Scorer reqScorer,
        Scorer optScorer)
    {
      super(reqScorer.weight);
      this.reqScorer = reqScorer;
      this.optScorer = optScorer;
    }
  
    @Override
    public int nextDoc() throws IOException {
      return reqScorer.nextDoc();
    }
    
    @Override
    public int advance(int target) throws IOException {
      return reqScorer.advance(target);
    }
    
    @Override
    public int docID() {
      return reqScorer.docID();
    }
    
    /** 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, eventually increased by the score
     * of the optional scorer when it also matches the current document.
     */
    @Override
    public float score() throws IOException {
      int curDoc = reqScorer.docID();
      float reqScore = reqScorer.score();
      if (optScorer == null) {
        return reqScore;
      }
      
      int optScorerDoc = optScorer.docID();
      if (optScorerDoc < curDoc && (optScorerDoc = optScorer.advance(curDoc)) == NO_MORE_DOCS) {
        optScorer = null;
        return reqScore;
      }
      
      return optScorerDoc == curDoc ? reqScore + optScorer.score() : reqScore;
    }
  
  }
  
  