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* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.index.analysis;
import org.apache.lucene.analysis.CharArraySet;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.miscellaneous.PatternKeywordMarkerFilter;
import org.apache.lucene.analysis.miscellaneous.SetKeywordMarkerFilter;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.env.Environment;
import org.elasticsearch.index.IndexSettings;
import java.util.Set;
import java.util.regex.Pattern;
/**
* A factory for creating keyword marker token filters that prevent tokens from
* being modified by stemmers. Two types of keyword marker filters are available:
* the {@link SetKeywordMarkerFilter} and the {@link PatternKeywordMarkerFilter}.
*
* The {@link SetKeywordMarkerFilter} uses a set of keywords to denote which tokens
* should be excluded from stemming. This filter is created if the settings include
* {@code keywords}, which contains the list of keywords, or {@code `keywords_path`},
* which contains a path to a file in the config directory with the keywords.
*
* The {@link PatternKeywordMarkerFilter} uses a regular expression pattern to match
* against tokens that should be excluded from stemming. This filter is created if
* the settings include {@code keywords_pattern}, which contains the regular expression
* to match against.
*/
public class KeywordMarkerTokenFilterFactory extends AbstractTokenFilterFactory {
private final CharArraySet keywordLookup;
private final Pattern keywordPattern;
public KeywordMarkerTokenFilterFactory(IndexSettings indexSettings, Environment env, String name, Settings settings) {
super(indexSettings, name, settings);
boolean ignoreCase =
settings.getAsBooleanLenientForPreEs6Indices(indexSettings.getIndexVersionCreated(), "ignore_case", false, deprecationLogger);
String patternString = settings.get("keywords_pattern");
if (patternString != null) {
// a pattern for matching keywords is specified, as opposed to a
// set of keyword strings to match against
if (settings.get("keywords") != null || settings.get("keywords_path") != null) {
throw new IllegalArgumentException(
"cannot specify both `keywords_pattern` and `keywords` or `keywords_path`");
}
keywordPattern = Pattern.compile(patternString);
keywordLookup = null;
} else {
Set<?> rules = Analysis.getWordSet(env, indexSettings.getIndexVersionCreated(), settings, "keywords");
if (rules == null) {
throw new IllegalArgumentException(
"keyword filter requires either `keywords`, `keywords_path`, " +
"or `keywords_pattern` to be configured");
}
// a set of keywords (or a path to them) is specified
keywordLookup = new CharArraySet(rules, ignoreCase);
keywordPattern = null;
}
}
@Override
public TokenStream create(TokenStream tokenStream) {
if (keywordPattern != null) {
return new PatternKeywordMarkerFilter(tokenStream, keywordPattern);
} else {
return new SetKeywordMarkerFilter(tokenStream, keywordLookup);
}
}
}