package org.apidesign.delegatingwriter;

 import java.io.IOException;

 import java.io.Writer;

 /** Writer alters each char from 'A' to 'Z' range with next one just like

  * old Romans did.

  *

  * @author Jaroslav Tulach

  */

 public class CryptoWriter extends AltBufferedWriter {

     public CryptoWriter(Writer out) {

         super(out);

     }

     public CryptoWriter(

         Writer out, AltBufferedWriter.Behaviour behaviour

     ) {

         super(out, behaviour);

     }

 /* The above code is here to let us simulate different behaviours of the append

  * method. In reality, the class would just subclass BufferedWriter, as shown bellow:

 BEGIN: writer.CryptoWriter

 public class CryptoWriter extends BufferedWriter {

     public CryptoWriter(Writer out) {

         super(out);

     }

     /* We need to override all known methods of BufferedWriter 

     * and do conversion of the argument char, string or char array.

     */

     @Override

     public void write(char[] buf, int off, int len) throws IOException {

         char[] arr = new char[len];

         for (int i = 0; i < len; i++) {

             arr[i] = encryptChar(buf[off + i]);

         }

         super.write(arr, 0, len);

     }

     @Override

     public void write(int c) throws IOException {

         super.write(encryptChar(c));

     }

     @Override

     public void write(String str, int off, int len) throws IOException {

         StringBuffer sb = new StringBuffer();

         for (int i = 0; i < len; i++) {

             sb.append(encryptChar(str.charAt(off + i)));

         }

         super.write(sb.toString(), 0, len);

     }

     private char encryptChar(int c) {

         if (c == 'Z') {

             return 'A';

         }

         if (c == 'z') {

             return 'a';

         }

         return (char)(c + 1);

     }

 // FINISH: writer.CryptoWriter

     /* delegates to write(cbuf, 0, cbuf.length)

     public void write(char[] cbuf) throws IOException {

     }

     */

     /* delegates to write(str, 0, str.length())

     public void write(String str) throws IOException {

     }

     */

 /* As this class was written against the version provided by JDK 1.4, we

  * could not override the append methods, as they did not exist at that time.

     @Override

     public Writer append(CharSequence csq) throws IOException {

     }

     @Override

     public Writer append(CharSequence csq, int start, int end) throws IOException {

     }

     @Override

     public Writer append(char c) throws IOException {

     }

 */

 }