| // Lucene version compatibility level 8.2.0 |
| using Lucene.Net.Analysis.OpenNlp.Tools; |
| using Lucene.Net.Analysis.TokenAttributes; |
| using Lucene.Net.Util; |
| using System.Collections.Generic; |
| |
| namespace Lucene.Net.Analysis.OpenNlp |
| { |
| /* |
| * 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> |
| /// Run OpenNLP POS tagger. Tags all terms in the <see cref="ITypeAttribute"/>. |
| /// </summary> |
| public sealed class OpenNLPPOSFilter : TokenFilter |
| { |
| private readonly IList<AttributeSource> sentenceTokenAttrs = new List<AttributeSource>(); |
| string[] tags = null; |
| private int tokenNum = 0; |
| private bool moreTokensAvailable = true; |
| |
| private readonly NLPPOSTaggerOp posTaggerOp; |
| private readonly ITypeAttribute typeAtt; |
| private readonly IFlagsAttribute flagsAtt; |
| private readonly ICharTermAttribute termAtt; |
| |
| public OpenNLPPOSFilter(TokenStream input, NLPPOSTaggerOp posTaggerOp) |
| : base(input) |
| { |
| this.posTaggerOp = posTaggerOp; |
| this.typeAtt = AddAttribute<ITypeAttribute>(); |
| this.flagsAtt = AddAttribute<IFlagsAttribute>(); |
| this.termAtt = AddAttribute<ICharTermAttribute>(); |
| } |
| |
| public override sealed bool IncrementToken() |
| { |
| if (!moreTokensAvailable) |
| { |
| Clear(); |
| return false; |
| } |
| if (tokenNum == sentenceTokenAttrs.Count) |
| { // beginning of stream, or previous sentence exhausted |
| string[] sentenceTokens = NextSentence(); |
| if (sentenceTokens == null) |
| { |
| Clear(); |
| return false; |
| } |
| tags = posTaggerOp.GetPOSTags(sentenceTokens); |
| tokenNum = 0; |
| } |
| ClearAttributes(); |
| sentenceTokenAttrs[tokenNum].CopyTo(this); |
| typeAtt.Type = tags[tokenNum++]; |
| return true; |
| } |
| |
| private string[] NextSentence() |
| { |
| var termList = new List<string>(); |
| sentenceTokenAttrs.Clear(); |
| bool endOfSentence = false; |
| while (!endOfSentence && (moreTokensAvailable = m_input.IncrementToken())) |
| { |
| termList.Add(termAtt.ToString()); |
| endOfSentence = 0 != (flagsAtt.Flags & OpenNLPTokenizer.EOS_FLAG_BIT); |
| sentenceTokenAttrs.Add(m_input.CloneAttributes()); |
| } |
| return termList.Count > 0 ? termList.ToArray() : null; |
| } |
| |
| public override void Reset() |
| { |
| base.Reset(); |
| moreTokensAvailable = true; |
| Clear(); |
| } |
| |
| private void Clear() |
| { |
| sentenceTokenAttrs.Clear(); |
| tags = null; |
| tokenNum = 0; |
| } |
| } |
| } |