/*
* 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 Token = Lucene.Net.Analysis.Token;
using TokenFilter = Lucene.Net.Analysis.TokenFilter;
using TokenStream = Lucene.Net.Analysis.TokenStream;
using TermAttribute = Lucene.Net.Analysis.Tokenattributes.TermAttribute;
using TypeAttribute = Lucene.Net.Analysis.Tokenattributes.TypeAttribute;
namespace Lucene.Net.Analysis.Standard
{
/// Normalizes tokens extracted with {@link StandardTokenizer}.
public sealed class StandardFilter:TokenFilter
{
/// Construct filtering in.
public StandardFilter(TokenStream in_Renamed):base(in_Renamed)
{
termAtt = (TermAttribute) AddAttribute(typeof(TermAttribute));
typeAtt = (TypeAttribute) AddAttribute(typeof(TypeAttribute));
}
private static readonly System.String APOSTROPHE_TYPE;
private static readonly System.String ACRONYM_TYPE;
// this filters uses attribute type
private TypeAttribute typeAtt;
private TermAttribute termAtt;
/// Returns the next token in the stream, or null at EOS.
/// Removes 's from the end of words.
/// Removes dots from acronyms.
///
public override bool IncrementToken()
{
if (!input.IncrementToken())
{
return false;
}
char[] buffer = termAtt.TermBuffer();
int bufferLength = termAtt.TermLength();
System.String type = typeAtt.Type();
if ((System.Object) type == (System.Object) APOSTROPHE_TYPE && bufferLength >= 2 && buffer[bufferLength - 2] == '\'' && (buffer[bufferLength - 1] == 's' || buffer[bufferLength - 1] == 'S'))
{
// Strip last 2 characters off
termAtt.SetTermLength(bufferLength - 2);
}
else if ((System.Object) type == (System.Object) ACRONYM_TYPE)
{
// remove dots
int upto = 0;
for (int i = 0; i < bufferLength; i++)
{
char c = buffer[i];
if (c != '.')
buffer[upto++] = c;
}
termAtt.SetTermLength(upto);
}
return true;
}
static StandardFilter()
{
APOSTROPHE_TYPE = StandardTokenizerImpl.TOKEN_TYPES[StandardTokenizerImpl.APOSTROPHE];
ACRONYM_TYPE = StandardTokenizerImpl.TOKEN_TYPES[StandardTokenizerImpl.ACRONYM];
}
}
}