subroutinesubscriptprivate

subroutine subscript(c, a, index, v)
    type(fypp_t), intent(inout) :: c    !! the state
    type(value_t), intent(in) :: a      !! the value
    integer, intent(in) :: index        !! the index
    type(value_t), intent(out) :: v     !! the item
    integer :: n, at

    select case (a%kind)
    case (V_STR); n = len(a%text)
    case (V_LIST, V_TUPLE); n = size(a%items)
    case default
        call fail(c, 'a value cannot be subscripted')
        return
    end select
    at = merge(index + n, index, index < 0) + 1
    if (at < 1 .or. at > n) then
        call fail(c, 'an index is out of range')
    else if (a%kind == V_STR) then
        call make_string(a%text(at:at), v)
    else
        v = a%items(at)
    end if
end subroutine subscript