StandardFilter.cs
上传用户:zhangkuixh
上传日期:2013-09-30
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文件大小:2k
- /*
- * Copyright 2004 The Apache Software Foundation
- *
- * Licensed 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 Lucene.Net.Analysis;
- namespace Lucene.Net.Analysis.Standard
- {
-
- /// <summary>Normalizes tokens extracted with {@link StandardTokenizer}. </summary>
-
- public sealed class StandardFilter : TokenFilter
- {
-
-
- /// <summary>Construct filtering <i>in</i>. </summary>
- public StandardFilter(TokenStream in_Renamed) : base(in_Renamed)
- {
- }
-
- private static readonly System.String APOSTROPHE_TYPE = Lucene.Net.Analysis.Standard.StandardTokenizerConstants.tokenImage[Lucene.Net.Analysis.Standard.StandardTokenizerConstants.APOSTROPHE];
- private static readonly System.String ACRONYM_TYPE = Lucene.Net.Analysis.Standard.StandardTokenizerConstants.tokenImage[Lucene.Net.Analysis.Standard.StandardTokenizerConstants.ACRONYM];
-
- /// <summary>Returns the next token in the stream, or null at EOS.
- /// <p>Removes <tt>'s</tt> from the end of words.
- /// <p>Removes dots from acronyms.
- /// </summary>
- public override Lucene.Net.Analysis.Token Next()
- {
- Lucene.Net.Analysis.Token t = input.Next();
-
- if (t == null)
- return null;
-
- System.String text = t.TermText();
- System.String type = t.Type();
-
- if (type == APOSTROPHE_TYPE && (text.EndsWith("'s") || text.EndsWith("'S")))
- {
- return new Lucene.Net.Analysis.Token(text.Substring(0, (text.Length - 2) - (0)), t.StartOffset(), t.EndOffset(), type);
- }
- else if (type == ACRONYM_TYPE)
- {
- // remove dots
- System.Text.StringBuilder trimmed = new System.Text.StringBuilder();
- for (int i = 0; i < text.Length; i++)
- {
- char c = text[i];
- if (c != '.')
- trimmed.Append(c);
- }
- return new Lucene.Net.Analysis.Token(trimmed.ToString(), t.StartOffset(), t.EndOffset(), type);
- }
- else
- {
- return t;
- }
- }
- }
- }