| using Egothor.Stemmer; |
| using J2N.IO; |
| using System.IO; |
| using System.Text; |
| |
| namespace Lucene.Net.Analysis.Stempel |
| { |
| /* |
| * 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. |
| */ |
| |
| /// <summary> |
| /// 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>). |
| /// <para> |
| /// Even though the stemmer tables supplied in the distribution package are built |
| /// for Polish language, there is nothing language-specific here. |
| /// </para> |
| /// </summary> |
| public class StempelStemmer |
| { |
| private readonly Trie stemmer = null; // LUCENENET: marked readonly |
| private readonly StringBuilder buffer = new StringBuilder(); // LUCENENET: marked readonly |
| |
| /// <summary> |
| /// Create a Stemmer using selected stemmer table |
| /// </summary> |
| /// <param name="stemmerTable">stemmer table.</param> |
| public StempelStemmer(Stream stemmerTable) |
| : this(Load(stemmerTable)) |
| { |
| } |
| |
| /// <summary> |
| /// Create a Stemmer using pre-loaded stemmer table |
| /// </summary> |
| /// <param name="stemmer">pre-loaded stemmer table</param> |
| public StempelStemmer(Trie stemmer) |
| { |
| this.stemmer = stemmer; |
| } |
| |
| /// <summary> |
| /// Load a stemmer table from an inputstream. |
| /// </summary> |
| public static Trie Load(Stream stemmerTable) |
| { |
| DataInputStream @in = null; |
| try |
| { |
| @in = new DataInputStream(stemmerTable); |
| string method = @in.ReadUTF().ToUpperInvariant(); |
| if (method.IndexOf('M') < 0) |
| { |
| return new Trie(@in); |
| } |
| else |
| { |
| return new MultiTrie2(@in); |
| } |
| } |
| finally |
| { |
| @in.Dispose(); |
| } |
| } |
| |
| /// <summary> |
| /// Stem a word. |
| /// </summary> |
| /// <param name="word">input word to be stemmed.</param> |
| /// <returns>stemmed word, or null if the stem could not be generated.</returns> |
| public StringBuilder Stem(string word) |
| { |
| string cmd = stemmer.GetLastOnPath(word); |
| |
| if (cmd == null) |
| return null; |
| |
| buffer.Length = 0; |
| buffer.Append(word); |
| |
| Diff.Apply(buffer, cmd); |
| |
| if (buffer.Length > 0) |
| return buffer; |
| else |
| return null; |
| } |
| } |
| } |