Merge Czech stemmer

CzechStemmerLight.java

@@ -0,0 +1,297 @@
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.io.Reader;
+import java.io.Writer;
+import java.nio.charset.StandardCharsets;
+
+/**
+ * @author Dolamic Ljiljana  University of Neuchatel
+ *
+ * Czech stemmer-removes case endings form nouns and adjectives, possessive adj.
+ * endings from names
+ * and takes care of palatalisation 
+ */
+public class CzechStemmerLight {
+
+	/**
+	 * A buffer of the current word being stemmed
+	 */
+	private StringBuffer sb=new StringBuffer();
+
+
+	/**
+	 * Default constructor
+	 */
+    public CzechStemmerLight(){} // constructor
+
+	public String stem(String input){
+
+		//
+		input=input.toLowerCase();
+
+		//reset string buffer
+		sb.delete(0,sb.length());
+		sb.insert(0,input);
+
+		// stemming...
+		//removes case endings from nouns and adjectives
+		removeCase(sb);
+
+		//removes possessive endings from names -ov- and -in-
+		removePossessives(sb);
+
+		String result = sb.toString();
+
+
+		return result;
+	}
+	private void palatalise(StringBuffer buffer){
+		int len=buffer.length();
+
+		if( buffer.substring( len- 2 ,len).equals("ci")||
+		    buffer.substring( len- 2 ,len).equals("ce")||		
+		    buffer.substring( len- 2 ,len).equals("\u010di")||  //-či
+		    buffer.substring( len- 2 ,len).equals("\u010de")){  //-če
+
+		    buffer.replace(len- 2 ,len, "k");
+		    return;
+		}
+		if( buffer.substring( len- 2 ,len).equals("zi")||
+		    buffer.substring( len- 2 ,len).equals("ze")||		
+		    buffer.substring( len- 2 ,len).equals("\u017ei")||  //-ži
+		    buffer.substring( len- 2 ,len).equals("\u017ee")){  //-že
+
+		    buffer.replace(len- 2 ,len, "h");
+		    return;
+		}
+		if( buffer.substring( len- 3 ,len).equals("\u010dt\u011b")||  //-čtě
+		    buffer.substring( len- 3 ,len).equals("\u010dti")||       //-čti
+		    buffer.substring( len- 3 ,len).equals("\u010dt\u00ed")){  //-čtí
+
+		    buffer.replace(len- 3 ,len, "ck");
+		    return;
+		}
+		if( buffer.substring( len- 3 ,len).equals("\u0161t\u011b")||  //-ště
+		    buffer.substring( len- 3 ,len).equals("\u0161ti")||       //-šti
+		    buffer.substring( len- 3 ,len).equals("\u0161t\u00ed")){  //-ští
+
+		    buffer.replace(len- 3 ,len, "sk");
+		    return;
+		}
+		buffer.delete( len- 1 , len);
+		return;
+	}//palatalise
+
+	private void removePossessives(StringBuffer buffer) {
+		int len=buffer.length();
+
+		if( len> 5 ){
+			if( buffer.substring( len- 2 ,len).equals("ov")){
+
+			    buffer.delete( len- 2 , len);
+			    return;
+			}
+			if( buffer.substring( len-2,len).equals("\u016fv")){ //-ův
+
+	        	    buffer.delete( len- 2 , len);
+		            return;
+			}
+		        if( buffer.substring( len- 2 ,len).equals("in")){
+
+			    buffer.delete( len- 1 , len);
+			    palatalise(buffer);
+			    return;
+			}
+		}
+		return;
+	}//removePossessives
+
+	private void removeCase(StringBuffer buffer) {
+		int len=buffer.length();
+		// 
+		if( (len> 7 )&&
+		    buffer.substring( len- 5 ,len).equals("atech")){
+
+		    buffer.delete( len- 5 , len);
+		    return;
+		}//len>7
+		if( len> 6 ){
+		      if(buffer.substring( len- 4 ,len).equals("\u011btem")){   //-ětem
+
+		         buffer.delete( len- 3 , len);
+		         palatalise(buffer);
+		         return;
+		      }
+		       if(buffer.substring( len- 4 ,len).equals("at\u016fm")){  //-atům
+		    	      buffer.delete( len- 4 , len);
+		    	      return;
+		      }
+
+		}
+		if( len> 5 ){
+			    if(buffer.substring( len-3,len).equals("ech")|| 
+				  buffer.substring( len-3,len).equals("ich")|| 
+				  buffer.substring( len-3,len).equals("\u00edch")){ //-ích
+
+				  buffer.delete( len-2 , len);
+				  palatalise(buffer);
+				  return;
+				}
+		                if(buffer.substring( len-3,len).equals("\u00e9ho")|| //-ého
+				   buffer.substring( len-3,len).equals("\u011bmi")||  //-ěmi
+				   buffer.substring( len-3,len).equals("emi")||
+				   buffer.substring( len-3,len).equals("\u00e9mu")||  //-ému
+				   buffer.substring( len-3,len).equals("\u011bte")||  //-ěte
+				   buffer.substring( len-3,len).equals("\u011bti")||  //-ěti
+				   buffer.substring( len-3,len).equals("iho")||
+				   buffer.substring( len-3,len).equals("\u00edho")||  //-ího
+				   buffer.substring( len-3,len).equals("\u00edmi")||  //-ími
+				   buffer.substring( len-3,len).equals("imu")){
+
+				   buffer.delete( len- 2 , len);
+				   palatalise(buffer);
+				   return;
+			        }
+		                if( buffer.substring( len-3,len).equals("\u00e1ch")|| //-ách
+				    buffer.substring( len-3,len).equals("ata")||
+				    buffer.substring( len-3,len).equals("aty")||
+				    buffer.substring( len-3,len).equals("\u00fdch")||   //-ých
+				    buffer.substring( len-3,len).equals("ama")||
+				    buffer.substring( len-3,len).equals("ami")||
+				    buffer.substring( len-3,len).equals("ov\u00e9")||   //-ové
+				    buffer.substring( len-3,len).equals("ovi")||
+				    buffer.substring( len-3,len).equals("\u00fdmi")){  //-ými
+
+		                    buffer.delete( len- 3 , len);
+		                    return;
+				}
+		}  
+		if( len> 4){
+				if(buffer.substring( len-2,len).equals("em")){
+
+			         buffer.delete( len- 1 , len);
+			         palatalise(buffer);
+			         return;
+
+			      }
+		                if( buffer.substring( len-2,len).equals("es")|| 
+				    buffer.substring( len-2,len).equals("\u00e9m")||    //-ém
+				    buffer.substring( len-2,len).equals("\u00edm")){   //-ím
+
+			            buffer.delete( len- 1 , len);
+			            palatalise(buffer);
+			            return;
+			        }
+		                if( buffer.substring( len-2,len).equals("\u016fm")){  //-ům
+
+			            buffer.delete( len- 2 , len);
+			            return;
+			        }
+		                if( buffer.substring( len-2,len).equals("at")|| 
+				    buffer.substring( len-2,len).equals("\u00e1m")||    //-ám
+				    buffer.substring( len-2,len).equals("os")||
+				    buffer.substring( len-2,len).equals("us")||   
+				    buffer.substring( len-2,len).equals("\u00fdm")||     //-ým
+				    buffer.substring( len-2,len).equals("mi")||   
+				    buffer.substring( len-2,len).equals("ou")){
+
+				    buffer.delete( len- 2 , len);
+				    return;
+				}
+		}//len>4
+		if( len> 3){
+			 if( buffer.substring( len-1,len).equals("e")||
+			    buffer.substring( len-1,len).equals("i")){
+
+			     palatalise(buffer);
+			     return;
+			}
+		            if( buffer.substring( len-1,len).equals("\u00ed")||  //-í
+				    buffer.substring( len-1,len).equals("\u011b")){      //-ě
+
+				    palatalise(buffer);
+				    return;
+				}
+		            if( buffer.substring( len-1,len).equals("u")||
+				    buffer.substring( len-1,len).equals("y")||
+				    buffer.substring( len-1,len).equals("\u016f")){  //-ů
+
+				    buffer.delete( len- 1 , len);
+				    return;
+
+				}
+		          if( buffer.substring( len-1,len).equals("a")||
+		        	  buffer.substring( len-1,len).equals("o")||
+				    buffer.substring( len-1,len).equals("\u00e1")||  // -á
+				    buffer.substring( len-1,len).equals("\u00e9")||  //-é
+				    buffer.substring( len-1,len).equals("\u00fd")){   //-ý
+
+				    buffer.delete( len- 1 , len);
+				    return;
+				}
+		}//len>3
+	}
+
+
+    private static void usage()
+    {
+        System.err.println("Usage: TestApp <algorithm> [<input file>] [-o <output file>]");
+    }
+
+    public static void main(String [] args) throws Throwable {
+        if (args.length < 1) {
+            usage();
+            return;
+        }
+
+        CzechStemmerLight stemmer = new CzechStemmerLight();
+
+	int arg = 1;
+
+	InputStream instream;
+	if (args.length > arg && !args[arg].equals("-o")) {
+	    instream = new FileInputStream(args[arg++]);
+	} else {
+	    instream = System.in;
+	}
+
+        OutputStream outstream;
+	if (args.length > arg) {
+            if (args.length != arg + 2 || !args[arg].equals("-o")) {
+                usage();
+                return;
+            }
+	    outstream = new FileOutputStream(args[arg + 1]);
+	} else {
+	    outstream = System.out;
+	}
+
+	Reader reader = new InputStreamReader(instream, StandardCharsets.UTF_8);
+	reader = new BufferedReader(reader);
+
+	Writer output = new OutputStreamWriter(outstream, StandardCharsets.UTF_8);
+	output = new BufferedWriter(output);
+
+	StringBuffer input = new StringBuffer();
+	int character;
+	while ((character = reader.read()) != -1) {
+	    char ch = (char) character;
+	    if (Character.isWhitespace(ch)) {
+		String result = stemmer.stem(input.toString());
+		output.write(result);
+		output.write('\n');
+		input.delete(0, input.length());
+	    } else {
+		input.append(ch < 127 ? Character.toLowerCase(ch) : ch);
+	    }
+	}
+	output.flush();
+    }
+
+}//CzechStemmer_1