/*
* 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.
*/
package org.apache.lucene.search.suggest.analyzing;
import java.io.IOException;
import java.util.Map;
import org.apache.lucene.analysis.CharArraySet;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.WordlistLoader; // jdocs
import org.apache.lucene.analysis.core.StopAnalyzer;
import org.apache.lucene.analysis.util.ResourceLoader;
import org.apache.lucene.analysis.util.ResourceLoaderAware;
import org.apache.lucene.analysis.util.TokenFilterFactory;
/**
* Factory for {@link SuggestStopFilter}.
*
* <pre class="prettyprint">
* <fieldType name="autosuggest" class="solr.TextField"
* positionIncrementGap="100" autoGeneratePhraseQueries="true">
* <analyzer>
* <tokenizer class="solr.WhitespaceTokenizerFactory"/>
* <filter class="solr.LowerCaseFilterFactory"/>
* <filter class="solr.SuggestStopFilterFactory" ignoreCase="true"
* words="stopwords.txt" format="wordset"/>
* </analyzer>
* </fieldType></pre>
*
* <p>
* All attributes are optional:
* </p>
* <ul>
* <li><code>ignoreCase</code> defaults to <code>false</code></li>
* <li><code>words</code> should be the name of a stopwords file to parse, if not
* specified the factory will use {@link StopAnalyzer#ENGLISH_STOP_WORDS_SET}
* </li>
* <li><code>format</code> defines how the <code>words</code> file will be parsed,
* and defaults to <code>wordset</code>. If <code>words</code> is not specified,
* then <code>format</code> must not be specified.
* </li>
* </ul>
* <p>
* The valid values for the <code>format</code> option are:
* </p>
* <ul>
* <li><code>wordset</code> - This is the default format, which supports one word per
* line (including any intra-word whitespace) and allows whole line comments
* begining with the "#" character. Blank lines are ignored. See
* {@link WordlistLoader#getLines WordlistLoader.getLines} for details.
* </li>
* <li><code>snowball</code> - This format allows for multiple words specified on each
* line, and trailing comments may be specified using the vertical line ("|").
* Blank lines are ignored. See
* {@link WordlistLoader#getSnowballWordSet WordlistLoader.getSnowballWordSet}
* for details.
* </li>
* </ul>
*/
public class SuggestStopFilterFactory extends TokenFilterFactory implements ResourceLoaderAware {
/** the default format, one word per line, whole line comments start with "#" */
public static final String FORMAT_WORDSET = "wordset";
/** multiple words may be specified on each line, trailing comments start with "|" */
public static final String FORMAT_SNOWBALL = "snowball";
private CharArraySet stopWords;
private final String stopWordFiles;
private final String format;
private final boolean ignoreCase;
/** Creates a new StopFilterFactory */
public SuggestStopFilterFactory(Map<String,String> args) {
super(args);
stopWordFiles = get(args, "words");
format = get(args, "format", (null == stopWordFiles ? null : FORMAT_WORDSET));
ignoreCase = getBoolean(args, "ignoreCase", false);
if (!args.isEmpty()) {
throw new IllegalArgumentException("Unknown parameters: " + args);
}
}
@Override
public void inform(ResourceLoader loader) throws IOException {
if (stopWordFiles != null) {
if (FORMAT_WORDSET.equalsIgnoreCase(format)) {
stopWords = getWordSet(loader, stopWordFiles, ignoreCase);
} else if (FORMAT_SNOWBALL.equalsIgnoreCase(format)) {
stopWords = getSnowballWordSet(loader, stopWordFiles, ignoreCase);
} else {
throw new IllegalArgumentException("Unknown 'format' specified for 'words' file: " + format);
}
} else {
if (null != format) {
throw new IllegalArgumentException("'format' can not be specified w/o an explicit 'words' file: " + format);
}
stopWords = new CharArraySet(StopAnalyzer.ENGLISH_STOP_WORDS_SET, ignoreCase);
}
}
/** Whether or not to ignore case */
public boolean isIgnoreCase() {
return ignoreCase;
}
/** Returns the configured stopword set */
public CharArraySet getStopWords() {
return stopWords;
}
@Override
public TokenStream create(TokenStream input) {
SuggestStopFilter suggestStopFilter = new SuggestStopFilter(input, stopWords);
return suggestStopFilter;
}
}