/*
*
* 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 System.Collections.Generic;
using System.IO;
using System.Linq;
using Lucene.Net.Analysis.Standard;
using Version = Lucene.Net.Util.Version;
namespace Lucene.Net.Analysis.El
{
/**
* {@link Analyzer} for the Greek language.
*
* Supports an external list of stopwords (words
* that will not be indexed at all).
* A default set of stopwords is used unless an alternative list is specified.
*
*
* NOTE: This class uses the same {@link Version}
* dependent settings as {@link StandardAnalyzer}.
*/
public sealed class GreekAnalyzer : Analyzer
{
/**
* List of typical Greek stopwords.
*/
private static readonly String[] GREEK_STOP_WORDS = {
"ο", "η", "το", "οι", "τα", "του", "τησ", "των", "τον",
"την", "και",
"κι", "κ", "ειμαι", "εισαι", "ειναι", "ειμαστε", "ειστε"
, "στο", "στον",
"στη", "στην", "μα", "αλλα", "απο", "για", "προσ", "με",
"σε", "ωσ",
"παρα", "αντι", "κατα", "μετα", "θα", "να", "δε", "δεν",
"μη", "μην",
"επι", "ενω", "εαν", "αν", "τοτε", "που", "πωσ", "ποιοσ"
, "ποια", "ποιο",
"ποιοι", "ποιεσ", "ποιων", "ποιουσ", "αυτοσ", "αυτη",
"αυτο", "αυτοι",
"αυτων", "αυτουσ", "αυτεσ", "αυτα", "εκεινοσ", "εκεινη",
"εκεινο",
"εκεινοι", "εκεινεσ", "εκεινα", "εκεινων", "εκεινουσ",
"οπωσ", "ομωσ",
"ισωσ", "οσο", "οτι"
};
/**
* Returns a set of default Greek-stopwords
* @return a set of default Greek-stopwords
*/
public static ISet GetDefaultStopSet()
{
return DefaultSetHolder.DEFAULT_SET;
}
private static class DefaultSetHolder
{
internal static ISet DEFAULT_SET = CharArraySet.UnmodifiableSet(new CharArraySet(GREEK_STOP_WORDS, false));
}
/**
* Contains the stopwords used with the {@link StopFilter}.
*/
private readonly ISet stopSet;
private readonly Version matchVersion;
public GreekAnalyzer(Version matchVersion)
: this(matchVersion, DefaultSetHolder.DEFAULT_SET)
{
}
/**
* Builds an analyzer with the given stop words
*
* @param matchVersion
* lucene compatibility version
* @param stopwords
* a stopword set
*/
public GreekAnalyzer(Version matchVersion, ISet stopwords)
{
stopSet = CharArraySet.UnmodifiableSet(CharArraySet.Copy(stopwords));
this.matchVersion = matchVersion;
}
/**
* Builds an analyzer with the given stop words.
* @param stopwords Array of stopwords to use.
* @deprecated use {@link #GreekAnalyzer(Version, Set)} instead
*/
public GreekAnalyzer(Version matchVersion, params string[] stopwords)
: this(matchVersion, StopFilter.MakeStopSet(stopwords))
{
}
/**
* Builds an analyzer with the given stop words.
* @deprecated use {@link #GreekAnalyzer(Version, Set)} instead
*/
public GreekAnalyzer(Version matchVersion, IDictionary stopwords)
: this(matchVersion, stopwords.Keys.ToArray())
{
}
/**
* Creates a {@link TokenStream} which tokenizes all the text in the provided {@link Reader}.
*
* @return A {@link TokenStream} built from a {@link StandardTokenizer} filtered with
* {@link GreekLowerCaseFilter} and {@link StopFilter}
*/
public override TokenStream TokenStream(String fieldName, TextReader reader)
{
TokenStream result = new StandardTokenizer(matchVersion, reader);
result = new GreekLowerCaseFilter(result);
result = new StopFilter(StopFilter.GetEnablePositionIncrementsVersionDefault(matchVersion),
result, stopSet);
return result;
}
private class SavedStreams
{
protected internal Tokenizer source;
protected internal TokenStream result;
};
/**
* Returns a (possibly reused) {@link TokenStream} which tokenizes all the text
* in the provided {@link Reader}.
*
* @return A {@link TokenStream} built from a {@link StandardTokenizer} filtered with
* {@link GreekLowerCaseFilter} and {@link StopFilter}
*/
public override TokenStream ReusableTokenStream(String fieldName, TextReader reader)
{
SavedStreams streams = (SavedStreams)PreviousTokenStream;
if (streams == null)
{
streams = new SavedStreams();
streams.source = new StandardTokenizer(matchVersion, reader);
streams.result = new GreekLowerCaseFilter(streams.source);
streams.result = new StopFilter(StopFilter.GetEnablePositionIncrementsVersionDefault(matchVersion),
streams.result, stopSet);
PreviousTokenStream = streams;
}
else
{
streams.source.Reset(reader);
}
return streams.result;
}
}
}