| /* |
| * 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.stempel; |
| |
| import java.io.BufferedInputStream; |
| import java.io.DataInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.util.Locale; |
| import org.egothor.stemmer.Diff; |
| import org.egothor.stemmer.Trie; |
| |
| /** |
| * Stemmer class is a convenient facade for other stemmer-related classes. The core stemming |
| * algorithm and its implementation is taken verbatim from the Egothor project ( <a |
| * href="http://www.egothor.org">www.egothor.org </a>). |
| * |
| * <p>Even though the stemmer tables supplied in the distribution package are built for Polish |
| * language, there is nothing language-specific here. |
| */ |
| public class StempelStemmer { |
| private Trie stemmer = null; |
| private StringBuilder buffer = new StringBuilder(); |
| |
| /** |
| * Create a Stemmer using selected stemmer table |
| * |
| * @param stemmerTable stemmer table. |
| */ |
| public StempelStemmer(InputStream stemmerTable) throws IOException { |
| this(load(stemmerTable)); |
| } |
| |
| /** |
| * Create a Stemmer using pre-loaded stemmer table |
| * |
| * @param stemmer pre-loaded stemmer table |
| */ |
| public StempelStemmer(Trie stemmer) { |
| this.stemmer = stemmer; |
| } |
| |
| /** Load a stemmer table from an inputstream. */ |
| public static Trie load(InputStream stemmerTable) throws IOException { |
| DataInputStream in = null; |
| try { |
| in = new DataInputStream(new BufferedInputStream(stemmerTable)); |
| String method = in.readUTF().toUpperCase(Locale.ROOT); |
| if (method.indexOf('M') < 0) { |
| return new org.egothor.stemmer.Trie(in); |
| } else { |
| return new org.egothor.stemmer.MultiTrie2(in); |
| } |
| } finally { |
| in.close(); |
| } |
| } |
| |
| /** |
| * Stem a word. |
| * |
| * @param word input word to be stemmed. |
| * @return stemmed word, or null if the stem could not be generated. |
| */ |
| public StringBuilder stem(CharSequence word) { |
| CharSequence cmd = stemmer.getLastOnPath(word); |
| |
| if (cmd == null) return null; |
| |
| buffer.setLength(0); |
| buffer.append(word); |
| |
| Diff.apply(buffer, cmd); |
| |
| if (buffer.length() > 0) return buffer; |
| else return null; |
| } |
| } |