/*
* 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.
*/
using System;
namespace Lucene.Net.Search
{
/// A Scorer for queries with a required subscorer and an excluding (prohibited) subscorer.
///
/// This Scorer
implements {@link Scorer#SkipTo(int)},
/// and it uses the skipTo() on the given scorers.
///
public class ReqExclScorer : Scorer
{
private Scorer reqScorer, exclScorer;
/// Construct a ReqExclScorer
.
/// The scorer that must match, except where
///
/// indicates exclusion.
///
public ReqExclScorer(Scorer reqScorer, Scorer exclScorer) : base(null)
{ // No similarity used.
this.reqScorer = reqScorer;
this.exclScorer = exclScorer;
}
private bool firstTime = true;
public override bool Next()
{
if (firstTime)
{
if (!exclScorer.Next())
{
exclScorer = null; // exhausted at start
}
firstTime = false;
}
if (reqScorer == null)
{
return false;
}
if (!reqScorer.Next())
{
reqScorer = null; // exhausted, nothing left
return false;
}
if (exclScorer == null)
{
return true; // reqScorer.next() already returned true
}
return ToNonExcluded();
}
/// Advance to non excluded doc.
///
On entry:
///
/// - reqScorer != null,
///
- exclScorer != null,
///
- reqScorer was advanced once via next() or skipTo()
/// and reqScorer.doc() may still be excluded.
///
/// Advances reqScorer a non excluded required doc, if any.
///
/// true iff there is a non excluded required doc.
///
private bool ToNonExcluded()
{
int exclDoc = exclScorer.Doc();
do
{
int reqDoc = reqScorer.Doc(); // may be excluded
if (reqDoc < exclDoc)
{
return true; // reqScorer advanced to before exclScorer, ie. not excluded
}
else if (reqDoc > exclDoc)
{
if (!exclScorer.SkipTo(reqDoc))
{
exclScorer = null; // exhausted, no more exclusions
return true;
}
exclDoc = exclScorer.Doc();
if (exclDoc > reqDoc)
{
return true; // not excluded
}
}
}
while (reqScorer.Next());
reqScorer = null; // exhausted, nothing left
return false;
}
public override int Doc()
{
return reqScorer.Doc(); // reqScorer may be null when next() or skipTo() already return false
}
/// Returns the score of the current document matching the query.
/// Initially invalid, until {@link #next()} is called the first time.
///
/// The score of the required scorer.
///
public override float Score()
{
return reqScorer.Score(); // reqScorer may be null when next() or skipTo() already return false
}
/// Skips to the first match beyond the current whose document number is
/// greater than or equal to a given target.
///
When this method is used the {@link #Explain(int)} method should not be used.
///
/// The target document number.
///
/// true iff there is such a match.
///
public override bool SkipTo(int target)
{
if (firstTime)
{
firstTime = false;
if (!exclScorer.SkipTo(target))
{
exclScorer = null; // exhausted
}
}
if (reqScorer == null)
{
return false;
}
if (exclScorer == null)
{
return reqScorer.SkipTo(target);
}
if (!reqScorer.SkipTo(target))
{
reqScorer = null;
return false;
}
return ToNonExcluded();
}
public override Explanation Explain(int doc)
{
Explanation res = new Explanation();
if (exclScorer.SkipTo(doc) && (exclScorer.Doc() == doc))
{
res.SetDescription("excluded");
}
else
{
res.SetDescription("not excluded");
res.AddDetail(reqScorer.Explain(doc));
}
return res;
}
}
}