/*
* 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.
*/
package org.exoplatform.services.jcr.impl.core.query.lucene;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.Similarity;
import java.io.IOException;
/**
* <code>MultiScorer</code> spans multiple Scorers and returns document numbers
* and score values in the order as supplied to the constructor of this
* <code>MultiScorer</code>.
*/
class MultiScorer extends Scorer
{
/**
* The sub scorers.
*/
private final Scorer[] scorers;
/**
* The document start numbers of the sub scorers.
*/
private final int[] starts;
/**
* Index of the current scorer.
*/
private int currentScorer;
/**
* The next document id to be returned
*/
private int currentDoc = -1;
/**
* Creates a new <code>MultiScorer</code> that spans multiple
* <code>scorers</code>.
*
* @param similarity the similarity implementation that should be use.
* @param scorers the sub scorers.
* @param starts the document number start for each sub scorer.
*/
MultiScorer(Similarity similarity, Scorer[] scorers, int[] starts)
{
super(similarity);
this.scorers = scorers;
this.starts = starts;
}
@Override
public int nextDoc() throws IOException
{
while (currentDoc != NO_MORE_DOCS)
{
if (scorers[currentScorer].nextDoc() != NO_MORE_DOCS)
{
currentDoc = scorers[currentScorer].docID() + starts[currentScorer];
return currentDoc;
}
else if (++currentScorer < scorers.length)
{
// advance to next scorer
}
else
{
// no more scorers
currentDoc = NO_MORE_DOCS;
}
}
return currentDoc;
}
@Override
public int docID()
{
return currentDoc;
}
@Override
public float score() throws IOException
{
return scorers[currentScorer].score();
}
@Override
public int advance(int target) throws IOException
{
if (currentDoc == NO_MORE_DOCS)
{
return currentDoc;
}
currentScorer = scorerIndex(target);
if (scorers[currentScorer].advance(target - starts[currentScorer]) != NO_MORE_DOCS)
{
currentDoc = scorers[currentScorer].docID() + starts[currentScorer];
return currentDoc;
}
else
{
if (++currentScorer < scorers.length)
{
// simply move to the next if there is any
currentDoc = nextDoc();
return currentDoc;
}
else
{
// no more document
currentDoc = NO_MORE_DOCS;
return currentDoc;
}
}
}
//--------------------------< internal >------------------------------------
/**
* Returns the scorer index for document <code>n</code>.
* Implementation copied from lucene MultiReader class.
*
* @param n document number.
* @return the scorer index.
*/
private int scorerIndex(int n)
{
int lo = 0; // search starts array
int hi = scorers.length - 1; // for first element less
while (hi >= lo)
{
int mid = (lo + hi) >> 1;
int midValue = starts[mid];
if (n < midValue)
{
hi = mid - 1;
}
else if (n > midValue)
{
lo = mid + 1;
}
else
{ // found a match
while (mid + 1 < scorers.length && starts[mid + 1] == midValue)
{
mid++; // scan to last match
}
return mid;
}
}
return hi;
}
}