45 semiregular_box_t<Val> value_;
52 std::ptrdiff_t n_ = 0;
56 explicit cursor(Val
const & value)
57 : value_(std::addressof(value))
59 Val
const & read()
const noexcept
63 bool equal(cursor
const & that)
const
75 void advance(std::ptrdiff_t d)
79 std::ptrdiff_t distance_to(cursor
const & that)
const
84 cursor begin_cursor()
const
86 return cursor{value_};
96 : value_(detail::move(value))