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PatternKeywordMarkerFilter.cs
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PatternKeywordMarkerFilter.cs
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using Lucene.Net.Analysis.TokenAttributes;
using System.Text.RegularExpressions;
namespace Lucene.Net.Analysis.Miscellaneous
{
/*
* 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>
/// Marks terms as keywords via the <see cref="KeywordAttribute"/>. Each token
/// that matches the provided pattern is marked as a keyword by setting
/// <see cref="KeywordAttribute.IsKeyword"/> to <c>true</c>.
/// </summary>
public sealed class PatternKeywordMarkerFilter : KeywordMarkerFilter
{
private readonly ICharTermAttribute termAtt;
private Match matcher;
private readonly Regex pattern;
/// <summary>
/// Create a new <see cref="PatternKeywordMarkerFilter"/>, that marks the current
/// token as a keyword if the tokens term buffer matches the provided
/// <see cref="Regex"/> via the <see cref="KeywordAttribute"/>.
/// </summary>
/// <param name="in">
/// <see cref="TokenStream"/> to filter </param>
/// <param name="pattern">
/// the pattern to apply to the incoming term buffer
/// </param>
public PatternKeywordMarkerFilter(TokenStream @in, Regex pattern)
: base(@in)
{
termAtt = AddAttribute<ICharTermAttribute>();
this.matcher = pattern.Match("");
this.pattern = pattern;
}
protected override bool IsKeyword()
{
matcher = pattern.Match(termAtt.ToString());
return matcher.Success;
}
}
}