/*
*
* 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;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Lucene.Net.Analysis;
using Lucene.Net.Analysis.Tokenattributes;
namespace Lucene.Net.Search.Highlight
{
public class SimpleSpanFragmenter : IFragmenter
{
private static int DEFAULT_FRAGMENT_SIZE = 100;
private int fragmentSize;
private int currentNumFrags;
private int position = -1;
private QueryScorer queryScorer;
private int waitForPos = -1;
private int textSize;
private ITermAttribute termAtt;
private IPositionIncrementAttribute posIncAtt;
private IOffsetAttribute offsetAtt;
/// QueryScorer that was used to score hits
public SimpleSpanFragmenter(QueryScorer queryScorer)
: this(queryScorer, DEFAULT_FRAGMENT_SIZE)
{
}
/// QueryScorer that was used to score hits
/// size in bytes of each fragment
public SimpleSpanFragmenter(QueryScorer queryScorer, int fragmentSize)
{
this.fragmentSize = fragmentSize;
this.queryScorer = queryScorer;
}
///
public bool IsNewFragment()
{
position += posIncAtt.PositionIncrement;
if (waitForPos == position)
{
waitForPos = -1;
}
else if (waitForPos != -1)
{
return false;
}
WeightedSpanTerm wSpanTerm = queryScorer.GetWeightedSpanTerm(termAtt.Term);
if (wSpanTerm != null)
{
List positionSpans = wSpanTerm.GetPositionSpans();
for (int i = 0; i < positionSpans.Count; i++)
{
if (positionSpans[i].Start == position)
{
waitForPos = positionSpans[i].End + 1;
break;
}
}
}
bool isNewFrag = offsetAtt.EndOffset >= (fragmentSize*currentNumFrags)
&& (textSize - offsetAtt.EndOffset) >= ((uint) fragmentSize >> 1);
if (isNewFrag)
{
currentNumFrags++;
}
return isNewFrag;
}
///
public void Start(String originalText, TokenStream tokenStream)
{
position = -1;
currentNumFrags = 1;
textSize = originalText.Length;
termAtt = tokenStream.AddAttribute();
posIncAtt = tokenStream.AddAttribute();
offsetAtt = tokenStream.AddAttribute();
}
}
}