read_file Subroutine

subroutine read_file(filename, val, error)
   use mctc_io_utils, only : next_line, read_next_token, io_error, token_type
   character(len=*), intent(in) :: filename
   integer, intent(out) :: val
   type(error_type), allocatable, intent(out) :: error

   integer :: io, stat, lnum, pos
   type(token_type) :: token
   character(len=:), allocatable :: line

   lnum = 0

   open(file=filename, newunit=io, status='old', iostat=stat)
   if (stat /= 0) then
      call fatal_error(error, "Error: Could not open file '"//filename//"'")
      return
   end if

   call next_line(io, line, pos, lnum, stat)
   if (stat == 0) &
      call read_next_token(line, pos, token, val, stat)
   if (stat /= 0) then
      call io_error(error, "Cannot read value from file", line, token, &
         filename, lnum, "expected integer value")
      return
   end if

   close(io, iostat=stat)

end subroutine read_file