Calendar#
A delay_statement is used to block further execution until a specified expiration time is reached. The expiration
time can be specified either as a particular point in time (in a delay_until_statement), or in seconds from the
current time (in a delay_relative_statement). The language-defined package Calendar provides definitions
for a type Time and associated operations, including a function Clock that returns the current time.
package Ada.Calendar
with Nonblocking, Global => in out synchronized is
type Time is private;
subtype Year_Number is Integer range 1901 .. 2399;
subtype Month_Number is Integer range 1 .. 12;
subtype Day_Number is Integer range 1 .. 31;
subtype Day_Duration is Duration range 0.0 .. 86_400.0;
function Clock return Time;
function Year (Date: Time) return Year_Number;
function Month (Date: Time) return Month_Number;
function Day (Date: Time) return Day_Number;
function Seconds(Date: Time) return Day_Duration;
procedure Split(Date : Time;
Year : out Year_Number;
Month : out Month_Number;
Day : out Day_Number;
Seconds: out Day_Duration);
function Time_Of(Year : Year_Number;
Month : Month_Number;
Day : Day_Number;
Seconds: Day_Duration := 0.0)
return Time;
function "+"(Left: Time ; Right: Duration) return Time;
function "+"(Left: Duration; Right: Time) return Time;
function "-"(Left: Time ; Right: Duration) return Time;
function "-"(Left: Time ; Right: Time) return Duration;
function "<" (Left, Right: Time) return Boolean;
function "<="(Left, Right: Time) return Boolean;
function ">" (Left, Right: Time) return Boolean;
function ">="(Left, Right: Time) return Boolean;
Time_Error: exception;
end Ada.Calendar;
Example of a relative delay statement
delay 3.0; -- delay 3.0 seconds
Example of a periodic task
declare
use Ada.Calendar;
Next_Time: Time := Clock + Period; -- Period is a global constant of type Duration
begin
loop -- repeated every Period seconds
delay until Next_Time;
... -- perform some actions
Next_Time := Next_Time + Period;
end loop;
end;
Time Zones#
package Ada.Calendar.Time_Zones
with Nonblocking, Global => in out synchronized is
-- Time zone manipulation:
type Time_Offset is range -28*60 .. 28*60;
Unknown_Zone_Error: exception;
function Local_Time_Offset(Date: Time := Clock) return Time_Offset;
function UTC_Time_Offset (Date: Time := Clock) return Time_Offset renames Local_Time_Offset;
end Ada.Calendar.Time_Zones;
Arithmetic#
package Ada.Calendar.Arithmetic
with Nonblocking, Global => in out synchronized is
-- Arithmetic on days:
type Day_Count is range -366*(1 + Year_Number'Last - Year_Number'First) ..
366*(1 + Year_Number'Last - Year_Number'First);
subtype Leap_Seconds_Count is Integer range -2047 .. 2047;
procedure Difference(Left, Right : Time;
Days : out Day_Count;
Seconds : out Duration;
Leap_Seconds: out Leap_Seconds_Count);
function "+"(Left: Time ; Right: Day_Count) return Time;
function "+"(Left: Day_Count; Right: Time) return Time;
function "-"(Left: Time ; Right: Day_Count) return Time;
function "-"(Left, Right: Time) return Day_Count;
end Ada.Calendar.Arithmetic;
Formatting#
with Ada.Calendar.Time_Zones;
package Ada.Calendar.Formatting
with Nonblocking, Global => in out synchronized is
type Day_Name is (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday);
function Day_of_Week(Date: Time) return Day_Name;
-- Hours:Minutes:Seconds access:
subtype Hour_Number is Natural range 0 .. 23;
subtype Second_Number is Natural range 0 .. 59;
subtype Minute_Number is Natural range 0 .. 59;
subtype Second_Duration is Day_Duration range 0.0 .. 1.0;
function Year (Date: Time; Time_Zone: Time_Zones.Time_Offset := 0) return Year_Number;
function Month (Date: Time; Time_Zone: Time_Zones.Time_Offset := 0) return Month_Number;
function Day (Date: Time; Time_Zone: Time_Zones.Time_Offset := 0) return Day_Number;
function Hour (Date: Time; Time_Zone: Time_Zones.Time_Offset := 0) return Hour_Number;
function Minute(Date: Time; Time_Zone: Time_Zones.Time_Offset := 0) return Minute_Number;
function Second (Date: Time) return Second_Number;
function Sub_Second(Date: Time) return Second_Duration;
function Seconds_Of(Hour : Hour_Number;
Minute : Minute_Number;
Second : Second_Number := 0;
Sub_Second: Second_Duration := 0.0)
return Day_Duration;
procedure Split(Seconds : Day_Duration;
Hour : out Hour_Number;
Minute : out Minute_Number;
Second : out Second_Number;
Sub_Second: out Second_Duration);
function Time_Of(Year : Year_Number;
Month : Month_Number;
Day : Day_Number;
Hour : Hour_Number;
Minute : Minute_Number;
Second : Second_Number;
Sub_Second : Second_Duration := 0.0;
Leap_Second: Boolean := False;
Time_Zone : Time_Zones.Time_Offset := 0)
return Time;
function Time_Of(Year : Year_Number;
Month : Month_Number;
Day : Day_Number;
Seconds : Day_Duration := 0.0;
Leap_Second: Boolean := False;
Time_Zone : Time_Zones.Time_Offset := 0)
return Time;
procedure Split(Date : Time;
Year : out Year_Number;
Month : out Month_Number;
Day : out Day_Number;
Hour : out Hour_Number;
Minute : out Minute_Number;
Second : out Second_Number;
Sub_Second: out Second_Duration;
Time_Zone : Time_Zones.Time_Offset := 0);
procedure Split(Date : Time;
Year : out Year_Number;
Month : out Month_Number;
Day : out Day_Number;
Hour : out Hour_Number;
Minute : out Minute_Number;
Second : out Second_Number;
Sub_Second : out Second_Duration;
Leap_Second: out Boolean;
Time_Zone : Time_Zones.Time_Offset := 0);
procedure Split(Date : Time;
Year : out Year_Number;
Month : out Month_Number;
Day : out Day_Number;
Seconds : out Day_Duration;
Leap_Second: out Boolean;
Time_Zone : Time_Zones.Time_Offset := 0);
-- Simple image and value:
function Image(Date : Time;
Include_Time_Fraction: Boolean := False;
Time_Zone : Time_Zones.Time_Offset := 0)
return String;
function Local_Image(Date: Time; Include_Time_Fraction: Boolean := False) return String is
(Image(Date, Include_Time_Fraction, Time_Zones.Local_Time_Offset(Date)));
function Value(Date: String; Time_Zone: Time_Zones.Time_Offset := 0) return Time;
function Image(Elapsed_Time: Duration; Include_Time_Fraction: Boolean := False) return String;
function Value(Elapsed_Time: String) return Duration;
end Ada.Calendar.Formatting;