| /* |
| * 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.analysis; |
| |
| |
| import java.util.Arrays; |
| import java.util.List; |
| |
| import org.apache.lucene.analysis.tokenattributes.CharTermAttribute; |
| |
| /** |
| * Removes stop words from a token stream. |
| */ |
| public class StopFilter extends FilteringTokenFilter { |
| |
| private final CharArraySet stopWords; |
| private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class); |
| |
| /** |
| * Constructs a filter which removes words from the input TokenStream that are |
| * named in the Set. |
| * |
| * @param in |
| * Input stream |
| * @param stopWords |
| * A {@link CharArraySet} representing the stopwords. |
| * @see #makeStopSet(java.lang.String...) |
| */ |
| public StopFilter(TokenStream in, CharArraySet stopWords) { |
| super(in); |
| this.stopWords = stopWords; |
| } |
| |
| /** |
| * Builds a Set from an array of stop words, |
| * appropriate for passing into the StopFilter constructor. |
| * This permits this stopWords construction to be cached once when |
| * an Analyzer is constructed. |
| * |
| * @param stopWords An array of stopwords |
| * @see #makeStopSet(java.lang.String[], boolean) passing false to ignoreCase |
| */ |
| public static CharArraySet makeStopSet(String... stopWords) { |
| return makeStopSet(stopWords, false); |
| } |
| |
| /** |
| * Builds a Set from an array of stop words, |
| * appropriate for passing into the StopFilter constructor. |
| * This permits this stopWords construction to be cached once when |
| * an Analyzer is constructed. |
| * |
| * @param stopWords A List of Strings or char[] or any other toString()-able list representing the stopwords |
| * @return A Set ({@link CharArraySet}) containing the words |
| * @see #makeStopSet(java.lang.String[], boolean) passing false to ignoreCase |
| */ |
| public static CharArraySet makeStopSet(List<?> stopWords) { |
| return makeStopSet(stopWords, false); |
| } |
| |
| /** |
| * Creates a stopword set from the given stopword array. |
| * |
| * @param stopWords An array of stopwords |
| * @param ignoreCase If true, all words are lower cased first. |
| * @return a Set containing the words |
| */ |
| public static CharArraySet makeStopSet(String[] stopWords, boolean ignoreCase) { |
| CharArraySet stopSet = new CharArraySet(stopWords.length, ignoreCase); |
| stopSet.addAll(Arrays.asList(stopWords)); |
| return stopSet; |
| } |
| |
| /** |
| * Creates a stopword set from the given stopword list. |
| * @param stopWords A List of Strings or char[] or any other toString()-able list representing the stopwords |
| * @param ignoreCase if true, all words are lower cased first |
| * @return A Set ({@link CharArraySet}) containing the words |
| */ |
| public static CharArraySet makeStopSet(List<?> stopWords, boolean ignoreCase){ |
| CharArraySet stopSet = new CharArraySet(stopWords.size(), ignoreCase); |
| stopSet.addAll(stopWords); |
| return stopSet; |
| } |
| |
| /** |
| * Returns the next input Token whose term() is not a stop word. |
| */ |
| @Override |
| protected boolean accept() { |
| return !stopWords.contains(termAtt.buffer(), 0, termAtt.length()); |
| } |
| |
| } |