package com.dlj.ir.analysis.ru;import java.util.Map;import java.util.WeakHashMap;/** * Russian stemmer-   * Done by Ljiljana Dolamic(University of Neuchatel, www.unine.ch/info/clef/) * * @author Ljiljana Doalmic. Email: ljiljana.dolamic@unine.ch * -removes case endings form nouns and adjectives,  */public class RussianStemmerLight {	/**	 * A cache of words and their stems	 */	static private Map<String, String> cache = new WeakHashMap<String, String>();	/**	 * A buffer of the current word being stemmed	 */	private StringBuffer sb=new StringBuffer();		/**	 * Default constructor	 */	public RussianStemmerLight(){	} // constructor	public String stem(String input){		String result = cache.get(input);		if (result != null)			return result;		//reset string buffer		sb.delete(0,sb.length());		sb.insert(0,input);		// stemming...		//removes case endings from nouns and adjectives		removeCase(sb);				normalize(sb);		result = sb.toString();		cache.put(input, result);		return result;	}	private void normalize(StringBuffer buffer) {		int len=buffer.length();		if( len>3){			if(buffer.substring( len - 1, len).equals("ь")){								buffer.delete( len - 1 , len);				return;			}					if(buffer.substring( len - 2, len).equals("нн")){								buffer.delete( len - 1 , len);				return;			}					if(buffer.substring( len -1,len).equals("и")){								buffer.delete( len - 1 , len);				return;			}		}//len>3			}	private void removeCase(StringBuffer buffer) {		int len=buffer.length();				// 		if( len> 6){			if(buffer.substring( len - 4 , len).equals("иями")||										buffer.substring( len - 4, len).equals("оями")){				buffer.delete( len - 4 , len);				return;			}		}//len>6		if( len>5 ){			if(buffer.substring( len - 3 , len).equals("иям")||					buffer.substring( len - 3 , len).equals("иях")||					buffer.substring( len - 3 , len).equals("оях")||					buffer.substring( len - 3 , len).equals("ями")||					buffer.substring( len - 3 , en).equals("oям")||					buffer.substring( len - 3 , en).equals("oьв")||					buffer.substring( len - 3 , len).equals("ами")||					buffer.substring( len - 3 , len).equals("его")||  					buffer.substring( len - 3 , len).equals("емu")||					buffer.substring( len - 3 , len).equals("ери")||					buffer.substring( len - 3 , len).equals("ими")||					buffer.substring( len - 3 , len).equals("ого")|| 					buffer.substring( len  -3 , len).equals("ому")||					buffer.substring( len - 3 , len).equals("ыми")||					buffer.substring( len - 3 , len).equals("оев"))}					){				buffer.delete( len - 3 , len);				return;			}					}//len>5		if( len> 4 ){			if(buffer.substring( len - 2 , len).equals("ая")|| 					buffer.substring( len - 2 , len).equals("яя")||					buffer.substring( len - 2 , len).equals("ях")||					buffer.substring( len - 2, len).equals("юю")||					buffer.substring( len - 2 , len).equals("ах")|| 					buffer.substring( len - 2 , len).equals("ею")|| 					  					buffer.substring( len - 2 , len).equals("их")||					buffer.substring( len - 2, len).equals("ия")||					buffer.substring( len - 2, len).equals("ию")||					  					buffer.substring( len - 2, len).equals("ьв")|| 					buffer.substring( len - 2, len).equals("ою")||					buffer.substring( len - 2 , len).equals("ую")||					buffer.substring( len - 2 , len).equals("ям")||   					buffer.substring( len - 2 , len).equals("ых")||										buffer.substring( len - 2 , len).equals("ея")||					buffer.substring( len - 2 , len).equals("ам")||					buffer.substring( len - 2 , len).equals("ее")|| 					buffer.substring( len - 2 , len).equals("ей")||    					buffer.substring( len - 2 , len).equals("ем")||    					buffer.substring( len - 2 , len).equals("ев")||					 					buffer.substring( len - 2 , len).equals("ий")||   					buffer.substring( len - 2 , len).equals("им")||					buffer.substring( len - 2 , len).equals("ое")||   					buffer.substring( len - 2 , len).equals("ой")||     					buffer.substring( len - 2 , len).equals("ом")||   					buffer.substring( len - 2 , len).equals("ов")||					buffer.substring( len - 2 , len).equals("ыe")|| 					buffer.substring( len - 2 , len).equals("ыj")||   					buffer.substring( len - 2 , len).equals("ым")||					buffer.substring( len - 2 , len).equals("ми")){ 				buffer.delete( len - 2 , len);				return;			}					}  				if( len> 3){			if( buffer.substring( len - 1 , len).equals("а")||					buffer.substring( len - 1 , len).equals("е")||					buffer.substring( len - 1 , len).equals("и")||  					buffer.substring( len - 1 , len).equals("о")||  					buffer.substring( len - 1 , len).equals("у")||					buffer.substring( len - 1 , len).equals("й")||					buffer.substring( len - 1 , len).equals("ы")||					buffer.substring( len - 1 , len).equals("я")||					buffer.substring( len - 1 , len).equals("ю")||					buffer.substring( len - 1 , len).equals("ь")||){   								buffer.delete( len - 1 , len);				return;			}		}//len>3	}	}