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--                                                                          --

--                         GNAT RUN-TIME COMPONENTS                         --

--                                                                          --

--                         G N A T . C A L E N D A R                        --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 1999-2009, Free Software Foundation, Inc.         --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

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--  This package extends Ada.Calendar to handle Hour, Minute, Second,

--  Second_Duration and Day_Of_Week and Day_In_Year from Calendar.Time.

--  Second_Duration precision depends on the target clock precision.

--

--  GNAT.Calendar provides the same kind of abstraction found in

--  Ada.Calendar. It provides Split and Time_Of to build and split a Time

--  data. And it provides accessor functions to get only one of Hour, Minute,

--  Second, Second_Duration. Other functions are to access more advanced

--  values like Day_Of_Week, Day_In_Year and Week_In_Year.

with Ada.Calendar;

with Interfaces.C;

package GNAT.Calendar is

   type Day_Name is

     (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday);

   subtype Hour_Number         is Natural range 0 .. 23;

   subtype Minute_Number       is Natural range 0 .. 59;

   subtype Second_Number       is Natural range 0 .. 59;

   subtype Second_Duration     is Ada.Calendar.Day_Duration range 0.0 .. 1.0;

   subtype Day_In_Year_Number  is Positive range 1 .. 366;

   subtype Week_In_Year_Number is Positive range 1 .. 53;

   No_Time : constant Ada.Calendar.Time;

   --  A constant set to the first date that can be represented by the type

   --  Time. It can be used to indicate an uninitialized date.

   function Hour       (Date : Ada.Calendar.Time) return Hour_Number;

   function Minute     (Date : Ada.Calendar.Time) return Minute_Number;

   function Second     (Date : Ada.Calendar.Time) return Second_Number;

   function Sub_Second (Date : Ada.Calendar.Time) return Second_Duration;

   --  Hour, Minute, Second and Sub_Second returns the complete time data for

   --  the Date (H:M:S.SS). See Ada.Calendar for Year, Month, Day accessors.

   --  Second_Duration precision depends on the target clock precision.

   function Day_Of_Week (Date : Ada.Calendar.Time) return Day_Name;

   --  Return the day name

   function Day_In_Year (Date : Ada.Calendar.Time) return Day_In_Year_Number;

   --  Return the day number in the year. (1st January is day 1 and 31st

   --  December is day 365 or 366 for leap year).

   procedure Split

     (Date       : Ada.Calendar.Time;

      Year       : out Ada.Calendar.Year_Number;

      Month      : out Ada.Calendar.Month_Number;

      Day        : out Ada.Calendar.Day_Number;

      Hour       : out Hour_Number;

      Minute     : out Minute_Number;

      Second     : out Second_Number;

      Sub_Second : out Second_Duration);

   --  Split the standard Ada.Calendar.Time data in date data (Year, Month,

   --  Day) and Time data (Hour, Minute, Second, Sub_Second)

   function Time_Of

     (Year       : Ada.Calendar.Year_Number;

      Month      : Ada.Calendar.Month_Number;

      Day        : Ada.Calendar.Day_Number;

      Hour       : Hour_Number;

      Minute     : Minute_Number;

      Second     : Second_Number;

      Sub_Second : Second_Duration := 0.0) return Ada.Calendar.Time;

   --  Return an Ada.Calendar.Time data built from the date and time values

   function Week_In_Year (Date : Ada.Calendar.Time) return Week_In_Year_Number;

   --  Return the week number as defined in ISO 8601. A week always starts on

   --  a Monday and the first week of a particular year is the one containing

   --  the first Thursday. A year may have 53 weeks when January 1st is a

   --  Wednesday and the year is leap or January 1st is a Thursday. Note that

   --  the last days of December may belong to the first week on the next year

   --  and conversely, the first days of January may belong to the last week

   --  of the last year.

   procedure Year_Week_In_Year

     (Date : Ada.Calendar.Time;

      Year : out Ada.Calendar.Year_Number;

      Week : out Week_In_Year_Number);

   --  Return the week number as defined in ISO 8601 along with the year in

   --  which the week occurs.

   --  C timeval conversion

   --  C timeval represent a duration (used in Select for example). This

   --  structure is composed of a number of seconds and a number of micro

   --  seconds. The timeval structure is not exposed here because its

   --  definition is target dependent. Interface to C programs is done via a

   --  pointer to timeval structure.

   type timeval is private;

   function To_Duration (T : not null access timeval) return Duration;

   function To_Timeval  (D : Duration) return timeval;

private

   --  This is a dummy declaration that should be the largest possible timeval

   --  structure of all supported targets.

   type timeval is array (1 .. 2) of Interfaces.C.long;

   function Julian_Day

     (Year  : Ada.Calendar.Year_Number;

      Month : Ada.Calendar.Month_Number;

      Day   : Ada.Calendar.Day_Number) return Integer;

   --  Compute Julian day number

   --

   --  The code of this function is a modified version of algorithm 199 from

   --  the Collected Algorithms of the ACM. The author of algorithm 199 is

   --  Robert G. Tantzen.

   No_Time : constant Ada.Calendar.Time :=

               Ada.Calendar.Time_Of

                 (Ada.Calendar.Year_Number'First,

                  Ada.Calendar.Month_Number'First,

                  Ada.Calendar.Day_Number'First);

end GNAT.Calendar;