package api;

 /**

  *

  * @author Jaroslav Tulach <jaroslav.tulach@apidesign.org>

  */

 final class CharSeq implements CharSequence {

     final char[] arr;

     final int off;

     final int len;

     final int c;

     public CharSeq(int c) {

         this.arr = null;

         this.off = 0;

         this.len = 1;

         this.c = c;

     }

     public CharSeq(char[] arr, int off, int len) {

         this.arr = arr;

         this.off = off;

         this.len = len;

         this.c = -1;

     }

     public int length() {

         return arr == null ? 1 : len;

     }

     public char charAt(int index) {

         if (index < 0) {

             throw new IndexOutOfBoundsException();

         }

         if (arr == null) {

             if (index > 0) {

                 throw new IndexOutOfBoundsException();

             }

             return (char)c;

         } else {

             if (index >= len) {

                 throw new IndexOutOfBoundsException();

             }

             return arr[off + index];

         }

     }

     public CharSequence subSequence(int start, int end) {

         if (end >= this.len) {

             throw new IndexOutOfBoundsException();

         }

         char[] array = arr == null ? new char[]{ (char)c } : arr;

         return new CharSeq(array, off + start, off + end);

     }

 }