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);

    }

}