read_lines Function

function read_lines(filename) result(lines)
    character(len=*), intent(in) :: filename
    type(string_t), allocatable :: lines(:)

    integer :: i
    character(len=:), allocatable :: content
    integer, allocatable :: first(:), last(:)

    content = read_text_file(filename)
    if (len(content) == 0) then
        allocate (lines(0))
        return
    end if

    call split_lines_first_last(content, first, last) 

    ! allocate lines from file content string
    allocate (lines(size(first)))
    do i = 1, size(first)
        allocate(lines(i)%s, source=content(first(i):last(i)))
    end do

end function read_lines