with Text_io;
procedure CAL is -- list successive dates etc. Example of Tasks
 
  DATE:string(1..20);
  Day:string(1..3);
  ANSWER:string(1..1);
 
  task YEARS is -- keep track of years, months and dates
    entry Get(DATE:out string);
    entry STOP;
  end YEARS;
 
  task WEEKS is -- keep track of days in week
    entry Get(DAY_OF_WEEK:out string);
    entry STOP;
  end WEEKS;
 
  procedure DBG(S:string) is
  begin Text_io.Put_line("Debug: " & S);
  end DBG;
 
  task body YEARS is separate;
  task body WEEKS is separate;
 
begin 
  loop
    DBG("l1"); 
    YEARS.Get(DATE); 
    DBG("l2");
    WEEKS.Get(Day);
    Text_io.Put(Day & "   " & DATE);
    Text_io.New_line;
    Text_io.Put("More (Y/N)?");
    Text_io.Get(ANSWER);
    exit when ANSWER /="Y" and ANSWER/="y";
  end loop;
 
  YEARS.STOP;
  WEEKS.STOP;
end CAL;
 
separate(CAL)
  task body YEARS is-- is a temporary body for testing purposes
    Year:integer:=1991;
    type MONTHS is 
    (JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC);
    subtype POSS_DAYS is integer range 1..31;
    type DAY_IN_MONTH_T is array(MONTHS) of POSS_DAYS;
    DAYS_IN_MONTH:DAY_IN_MONTH_T:=
    DAY_IN_MONTH_T'(SEP|APR|JUN|NOV=>30, FEB=>28, others=>31);
    Month:MONTHS:=MAY;
    Day:POSS_DAYS:=20;
    DONE:boolean:=false;
 
    function LAST_DAY(M:MONTHS) return POSS_DAYS is
    begin if M/=FEB then return DAYS_IN_MONTH(M);
      elsif (Year mod 100/=0 and Year mod 4=0) or
      (Year mod 100=0 and (Year/100) mod 4 = 0) then
        return 29;
      else return 28;
      end if;
    end LAST_DAY;
 
  procedure DBG(S:string) is
  begin Text_io.Put_line("Debug: " & S);
  end DBG;
 
  begin
    DBG("y1");
    Time:
    loop -- beginning of the year
      DBG("y2");
      loop -- beginning of a month
        DBG("y3");
        loop -- beginning of a day
          DBG("y4");
          select
            accept Get(DATE:out string) do
              DATE:=integer'image(Day)&"/"&MONTHS'image(Month)&"/"
              & integer'image(Year);
              DONE:=false;
            end;
          or
            accept STOP do DONE:=true;
            end;
          end select;
          exit Time when DONE;
          exit when Day=LAST_DAY(Month);
          Day:=Day+1;
        end loop;
        exit Time when DONE;
        -- day=last_day(month);
        Day:=1;
        exit when Month=DEC;
        Month:=MONTHS'succ(Month);
      end loop;
      exit Time when DONE;
      -- day=1 and month=Dec
      Month:=JAN;
      Year:=Year+1;
    end loop Time;
  end YEARS;
 
separate(CAL)
  task body WEEKS is--  starting calendar on a Monday only
    type WEEK is (MON, TUE, WED, THU, FRI, SAT, SUN);
    package WIO is new Text_io.ENUMERATION_IO(WEEK);
    DONE:boolean:=false;
  begin
    Time:
    loop
      for Day in WEEK loop
        select
          accept STOP do DONE:=true;
          end;
        or
          accept Get(DAY_OF_WEEK:out string) do
            DAY_OF_WEEK:=WEEK'image(Day);
            DONE:=false;
          end;
        end select;
        exit Time when DONE;
      end loop;
    end loop Time;
  end WEEKS;