package org.apache.lucene.analysis.de; /** * 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. */ /* * This algorithm is updated based on code located at: * http://members.unine.ch/jacques.savoy/clef/ * * Full copyright for that code follows: */ /* * Copyright (c) 2005, Jacques Savoy * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * Redistributions of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. Redistributions in binary * form must reproduce the above copyright notice, this list of conditions and * the following disclaimer in the documentation and/or other materials * provided with the distribution. Neither the name of the author nor the names * of its contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /** * Light Stemmer for German. * <p> * This stemmer implements the "UniNE" algorithm in: * <i>Light Stemming Approaches for the French, Portuguese, German and Hungarian Languages</i> * Jacques Savoy */ public class GermanLightStemmer { public int stem(char s[], int len) { for (int i = 0; i < len; i++) switch(s[i]) { case 'ä': case 'à': case 'á': case 'â': s[i] = 'a'; break; case 'ö': case 'ò': case 'ó': case 'ô': s[i] = 'o'; break; case 'ï': case 'ì': case 'í': case 'î': s[i] = 'i'; break; case 'ü': case 'ù': case 'ú': case 'û': s[i] = 'u'; break; } len = step1(s, len); return step2(s, len); } private boolean stEnding(char ch) { switch(ch) { case 'b': case 'd': case 'f': case 'g': case 'h': case 'k': case 'l': case 'm': case 'n': case 't': return true; default: return false; } } private int step1(char s[], int len) { if (len > 5 && s[len-3] == 'e' && s[len-2] == 'r' && s[len-1] == 'n') return len - 3; if (len > 4 && s[len-2] == 'e') switch(s[len-1]) { case 'm': case 'n': case 'r': case 's': return len - 2; } if (len > 3 && s[len-1] == 'e') return len - 1; if (len > 3 && s[len-1] == 's' && stEnding(s[len-2])) return len - 1; return len; } private int step2(char s[], int len) { if (len > 5 && s[len-3] == 'e' && s[len-2] == 's' && s[len-1] == 't') return len - 3; if (len > 4 && s[len-2] == 'e' && (s[len-1] == 'r' || s[len-1] == 'n')) return len - 2; if (len > 4 && s[len-2] == 's' && s[len-1] == 't' && stEnding(s[len-3])) return len - 2; return len; } }