| // lucene version compatibility level: 4.8.1 |
| using Lucene.Net.Analysis.Phonetic.Language; |
| using Lucene.Net.Analysis.TokenAttributes; |
| using System; |
| |
| namespace Lucene.Net.Analysis.Phonetic |
| { |
| /* |
| * 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> |
| /// Create tokens for phonetic matches. |
| /// See the Language namespace. |
| /// </summary> |
| public sealed class PhoneticFilter : TokenFilter |
| { |
| /// <summary>true if encoded tokens should be added as synonyms</summary> |
| private readonly bool inject = true; // LUCENENET: marked readonly |
| /// <summary>phonetic encoder</summary> |
| private readonly IStringEncoder encoder = null; // LUCENENET: marked readonly |
| /// <summary>captured state, non-null when <c>inject=true</c> and a token is buffered</summary> |
| private State save = null; |
| private readonly ICharTermAttribute termAtt; |
| private readonly IPositionIncrementAttribute posAtt; |
| |
| /// <summary> |
| /// Creates a <see cref="PhoneticFilter"/> with the specified encoder, and either |
| /// adding encoded forms as synonyms (<c>inject=true</c>) or |
| /// replacing them. |
| /// </summary> |
| public PhoneticFilter(TokenStream input, IStringEncoder encoder, bool inject) |
| : base(input) |
| { |
| this.encoder = encoder; |
| this.inject = inject; |
| this.termAtt = AddAttribute<ICharTermAttribute>(); |
| this.posAtt = AddAttribute<IPositionIncrementAttribute>(); |
| } |
| |
| public override bool IncrementToken() |
| { |
| if (save != null) |
| { |
| // clearAttributes(); // not currently necessary |
| RestoreState(save); |
| save = null; |
| return true; |
| } |
| |
| if (!m_input.IncrementToken()) return false; |
| |
| // pass through zero-length terms |
| if (termAtt.Length == 0) return true; |
| |
| string value = termAtt.ToString(); |
| string phonetic = null; |
| try |
| { |
| string v = encoder.Encode(value); |
| if (v.Length > 0 && !value.Equals(v, StringComparison.Ordinal)) |
| { |
| phonetic = v; |
| } |
| } |
| catch (Exception) { /* ignored */ } // just use the direct text |
| |
| if (phonetic == null) return true; |
| |
| if (!inject) |
| { |
| // just modify this token |
| termAtt.SetEmpty().Append(phonetic); |
| return true; |
| } |
| |
| // We need to return both the original and the phonetic tokens. |
| // to avoid a orig=captureState() change_to_phonetic() saved=captureState() restoreState(orig) |
| // we return the phonetic alternative first |
| |
| int origOffset = posAtt.PositionIncrement; |
| posAtt.PositionIncrement = 0; |
| save = CaptureState(); |
| |
| posAtt.PositionIncrement = origOffset; |
| termAtt.SetEmpty().Append(phonetic); |
| return true; |
| } |
| |
| public override void Reset() |
| { |
| m_input.Reset(); |
| save = null; |
| } |
| } |
| } |