/*
*
* 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.Collections;
using Lucene.Net.Analysis.Standard;
using Lucene.Net.Support;
using Version = Lucene.Net.Util.Version;
namespace Lucene.Net.Analysis.Nl
{
/*
* {@link Analyzer} for Dutch language.
*
* Supports an external list of stopwords (words that
* will not be indexed at all), an external list of exclusions (word that will
* not be stemmed, but indexed) and an external list of word-stem pairs that overrule
* the algorithm (dictionary stemming).
* A default set of stopwords is used unless an alternative list is specified, but the
* exclusion list is empty by default.
*
*
* NOTE: This class uses the same {@link Version}
* dependent settings as {@link StandardAnalyzer}.
*/
public class DutchAnalyzer : Analyzer
{
/*
* List of typical Dutch stopwords.
* @deprecated use {@link #getDefaultStopSet()} instead
*/
public static readonly String[] DUTCH_STOP_WORDS =
{
"de", "en", "van", "ik", "te", "dat", "die", "in", "een",
"hij", "het", "niet", "zijn", "is", "was", "op", "aan", "met", "als", "voor", "had",
"er", "maar", "om", "hem", "dan", "zou", "of", "wat", "mijn", "men", "dit", "zo",
"door", "over", "ze", "zich", "bij", "ook", "tot", "je", "mij", "uit", "der", "daar",
"haar", "naar", "heb", "hoe", "heeft", "hebben", "deze", "u", "want", "nog", "zal",
"me", "zij", "nu", "ge", "geen", "omdat", "iets", "worden", "toch", "al", "waren",
"veel", "meer", "doen", "toen", "moet", "ben", "zonder", "kan", "hun", "dus",
"alles", "onder", "ja", "eens", "hier", "wie", "werd", "altijd", "doch", "wordt",
"wezen", "kunnen", "ons", "zelf", "tegen", "na", "reeds", "wil", "kon", "niets",
"uw", "iemand", "geweest", "andere"
};
/*
* Returns an unmodifiable instance of the default stop-words set.
* @return an unmodifiable instance of the default stop-words set.
*/
public static ISet getDefaultStopSet()
{
return DefaultSetHolder.DEFAULT_STOP_SET;
}
static class DefaultSetHolder
{
internal static readonly ISet DEFAULT_STOP_SET = CharArraySet
.UnmodifiableSet(new CharArraySet((IEnumerable)DUTCH_STOP_WORDS, false));
}
/*
* Contains the stopwords used with the StopFilter.
*/
private readonly ISet stoptable;
/*
* Contains words that should be indexed but not stemmed.
*/
private ISet excltable = Support.Compatibility.SetFactory.CreateHashSet();
private IDictionary stemdict = new HashMap();
private readonly Version matchVersion;
/*
* Builds an analyzer with the default stop words ({@link #DUTCH_STOP_WORDS})
* and a few default entries for the stem exclusion table.
*
*/
public DutchAnalyzer(Version matchVersion)
: this(matchVersion, DefaultSetHolder.DEFAULT_STOP_SET)
{
stemdict.Add("fiets", "fiets"); //otherwise fiet
stemdict.Add("bromfiets", "bromfiets"); //otherwise bromfiet
stemdict.Add("ei", "eier");
stemdict.Add("kind", "kinder");
}
public DutchAnalyzer(Version matchVersion, ISet stopwords)
: this(matchVersion, stopwords, CharArraySet.EMPTY_SET)
{
}
public DutchAnalyzer(Version matchVersion, ISet stopwords, ISet stemExclusionTable)
{
stoptable = CharArraySet.UnmodifiableSet(CharArraySet.Copy(stopwords));
excltable = CharArraySet.UnmodifiableSet(CharArraySet.Copy(stemExclusionTable));
this.matchVersion = matchVersion;
SetOverridesTokenStreamMethod();
}
/*
* Builds an analyzer with the given stop words.
*
* @param matchVersion
* @param stopwords
* @deprecated use {@link #DutchAnalyzer(Version, Set)} instead
*/
public DutchAnalyzer(Version matchVersion, params string[] stopwords)
: this(matchVersion, StopFilter.MakeStopSet(stopwords))
{
}
/*
* Builds an analyzer with the given stop words.
*
* @param stopwords
* @deprecated use {@link #DutchAnalyzer(Version, Set)} instead
*/
public DutchAnalyzer(Version matchVersion, HashSet stopwords)
: this(matchVersion, (ISet)stopwords)
{
}
/*
* Builds an analyzer with the given stop words.
*
* @param stopwords
* @deprecated use {@link #DutchAnalyzer(Version, Set)} instead
*/
public DutchAnalyzer(Version matchVersion, FileInfo stopwords)
{
// this is completely broken!
SetOverridesTokenStreamMethod();
try
{
stoptable = WordlistLoader.GetWordSet(stopwords);
}
catch (IOException e)
{
// TODO: throw IOException
throw new Exception("", e);
}
this.matchVersion = matchVersion;
}
/*
* Builds an exclusionlist from an array of Strings.
*
* @param exclusionlist
* @deprecated use {@link #DutchAnalyzer(Version, Set, Set)} instead
*/
public void SetStemExclusionTable(params string[] exclusionlist)
{
excltable = StopFilter.MakeStopSet(exclusionlist);
PreviousTokenStream = null; // force a new stemmer to be created
}
/*
* Builds an exclusionlist from a Hashtable.
* @deprecated use {@link #DutchAnalyzer(Version, Set, Set)} instead
*/
public void SetStemExclusionTable(ISet exclusionlist)
{
excltable = exclusionlist;
PreviousTokenStream = null; // force a new stemmer to be created
}
/*
* Builds an exclusionlist from the words contained in the given file.
* @deprecated use {@link #DutchAnalyzer(Version, Set, Set)} instead
*/
public void SetStemExclusionTable(FileInfo exclusionlist)
{
try
{
excltable = WordlistLoader.GetWordSet(exclusionlist);
PreviousTokenStream = null; // force a new stemmer to be created
}
catch (IOException e)
{
// TODO: throw IOException
throw new Exception("", e);
}
}
/*
* Reads a stemdictionary file , that overrules the stemming algorithm
* This is a textfile that contains per line
* word\tstem, i.e: two tab seperated words
*/
public void SetStemDictionary(FileInfo stemdictFile)
{
try
{
stemdict = WordlistLoader.GetStemDict(stemdictFile);
PreviousTokenStream = null; // force a new stemmer to be created
}
catch (IOException e)
{
// TODO: throw IOException
throw new Exception(string.Empty, e);
}
}
/*
* 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 StandardFilter}, {@link StopFilter},
* and {@link DutchStemFilter}
*/
public override TokenStream TokenStream(String fieldName, TextReader reader)
{
TokenStream result = new StandardTokenizer(matchVersion, reader);
result = new StandardFilter(result);
result = new StopFilter(StopFilter.GetEnablePositionIncrementsVersionDefault(matchVersion),
result, stoptable);
result = new DutchStemFilter(result, excltable, stemdict);
return result;
}
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 StandardFilter}, {@link StopFilter},
* and {@link DutchStemFilter}
*/
public override TokenStream ReusableTokenStream(String fieldName, TextReader reader)
{
if (overridesTokenStreamMethod)
{
// LUCENE-1678: force fallback to tokenStream() if we
// have been subclassed and that subclass overrides
// tokenStream but not reusableTokenStream
return TokenStream(fieldName, reader);
}
SavedStreams streams = (SavedStreams)PreviousTokenStream;
if (streams == null)
{
streams = new SavedStreams();
streams.source = new StandardTokenizer(matchVersion, reader);
streams.result = new StandardFilter(streams.source);
streams.result = new StopFilter(StopFilter.GetEnablePositionIncrementsVersionDefault(matchVersion),
streams.result, stoptable);
streams.result = new DutchStemFilter(streams.result, excltable, stemdict);
PreviousTokenStream = streams;
}
else
{
streams.source.Reset(reader);
}
return streams.result;
}
}
}