| using Lucene.Net.Analysis; |
| using Lucene.Net.Analysis.TokenAttributes; |
| using System.Collections.Generic; |
| |
| namespace Lucene.Net.Search.Highlight |
| { |
| /* |
| * 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. |
| */ |
| |
| /// <summary> |
| /// <see cref="IFragmenter"/> implementation which breaks text up into same-size |
| /// fragments but does not split up <see cref="Search.Spans.Spans"/>. This is a simple sample class. |
| /// </summary> |
| 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 ICharTermAttribute termAtt; |
| private IPositionIncrementAttribute posIncAtt; |
| private IOffsetAttribute offsetAtt; |
| |
| /// <param name="queryScorer"><see cref="QueryScorer"/> that was used to score hits</param> |
| public SimpleSpanFragmenter(QueryScorer queryScorer) |
| : this(queryScorer, DEFAULT_FRAGMENT_SIZE) |
| { |
| } |
| |
| /// <param name="queryScorer"><see cref="QueryScorer"/> that was used to score hits</param> |
| /// <param name="fragmentSize">size in bytes of each fragment</param> |
| public SimpleSpanFragmenter(QueryScorer queryScorer, int fragmentSize) |
| { |
| this.fragmentSize = fragmentSize; |
| this.queryScorer = queryScorer; |
| } |
| |
| /// <seealso cref="IFragmenter.IsNewFragment()"/> |
| public virtual bool IsNewFragment() |
| { |
| position += posIncAtt.PositionIncrement; |
| |
| if (waitForPos == position) |
| { |
| waitForPos = -1; |
| } |
| else if (waitForPos != -1) |
| { |
| return false; |
| } |
| |
| WeightedSpanTerm wSpanTerm = queryScorer.GetWeightedSpanTerm(termAtt.ToString()); |
| |
| if (wSpanTerm != null) |
| { |
| IList<PositionSpan> positionSpans = wSpanTerm.PositionSpans; |
| |
| 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) >= (int)((uint)fragmentSize >> 1); |
| |
| |
| if (isNewFrag) |
| { |
| currentNumFrags++; |
| } |
| |
| return isNewFrag; |
| } |
| |
| /// <seealso cref="IFragmenter.Start(string, TokenStream)"/> |
| public virtual void Start(string originalText, TokenStream tokenStream) |
| { |
| position = -1; |
| currentNumFrags = 1; |
| textSize = originalText.Length; |
| termAtt = tokenStream.AddAttribute<ICharTermAttribute>(); |
| posIncAtt = tokenStream.AddAttribute<IPositionIncrementAttribute>(); |
| offsetAtt = tokenStream.AddAttribute<IOffsetAttribute>(); |
| } |
| } |
| } |