Method get_ptr

src/include/buffer.h:202–210

	return r;
      }
      ptr get_ptr(size_t len) {
	if (deep) {
	  return buffer::copy(get_pos_add(len), len);
	} else {
	  size_t off = pos - bp->c_str();
	  *this += len;
	  return ptr(*bp, off, len);
	}
      }

      iterator_impl& operator+=(size_t len);