package org.apache.lucene.analysis.compound;
/*
* 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.
*/
import java.util.Set;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.util.CharArraySet;
import org.apache.lucene.util.Version;
/**
* A {@link TokenFilter} that decomposes compound words found in many Germanic languages.
* <p>
* "Donaudampfschiff" becomes Donau, dampf, schiff so that you can find
* "Donaudampfschiff" even when you only enter "schiff".
* It uses a brute-force algorithm to achieve this.
* <p>
* You must specify the required {@link Version} compatibility when creating
* CompoundWordTokenFilterBase:
* <ul>
* <li>As of 3.1, CompoundWordTokenFilterBase correctly handles Unicode 4.0
* supplementary characters in strings and char arrays provided as compound word
* dictionaries.
* </ul>
*/
public class DictionaryCompoundWordTokenFilter extends CompoundWordTokenFilterBase {
/**
* Creates a new {@link DictionaryCompoundWordTokenFilter}
*
* @param matchVersion
* Lucene version to enable correct Unicode 4.0 behavior in the
* dictionaries if Version > 3.0. See <a
* href="CompoundWordTokenFilterBase.html#version"
* >CompoundWordTokenFilterBase</a> for details.
* @param input
* the {@link TokenStream} to process
* @param dictionary
* the word dictionary to match against.
*/
public DictionaryCompoundWordTokenFilter(Version matchVersion, TokenStream input, CharArraySet dictionary) {
super(matchVersion, input, dictionary);
if (dictionary == null) {
throw new IllegalArgumentException("dictionary cannot be null");
}
}
/**
* Creates a new {@link DictionaryCompoundWordTokenFilter}
*
* @param matchVersion
* Lucene version to enable correct Unicode 4.0 behavior in the
* dictionaries if Version > 3.0. See <a
* href="CompoundWordTokenFilterBase.html#version"
* >CompoundWordTokenFilterBase</a> for details.
* @param input
* the {@link TokenStream} to process
* @param dictionary
* the word dictionary to match against.
* @param minWordSize
* only words longer than this get processed
* @param minSubwordSize
* only subwords longer than this get to the output stream
* @param maxSubwordSize
* only subwords shorter than this get to the output stream
* @param onlyLongestMatch
* Add only the longest matching subword to the stream
*/
public DictionaryCompoundWordTokenFilter(Version matchVersion, TokenStream input, CharArraySet dictionary,
int minWordSize, int minSubwordSize, int maxSubwordSize, boolean onlyLongestMatch) {
super(matchVersion, input, dictionary, minWordSize, minSubwordSize, maxSubwordSize, onlyLongestMatch);
if (dictionary == null) {
throw new IllegalArgumentException("dictionary cannot be null");
}
}
@Override
protected void decompose() {
final int len = termAtt.length();
for (int i=0;i<=len-this.minSubwordSize;++i) {
CompoundToken longestMatchToken=null;
for (int j=this.minSubwordSize;j<=this.maxSubwordSize;++j) {
if(i+j>len) {
break;
}
if(dictionary.contains(termAtt.buffer(), i, j)) {
if (this.onlyLongestMatch) {
if (longestMatchToken!=null) {
if (longestMatchToken.txt.length()<j) {
longestMatchToken=new CompoundToken(i,j);
}
} else {
longestMatchToken=new CompoundToken(i,j);
}
} else {
tokens.add(new CompoundToken(i,j));
}
}
}
if (this.onlyLongestMatch && longestMatchToken!=null) {
tokens.add(longestMatchToken);
}
}
}
}