gcc/ada/libgnat/g-calend.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                         G N A T . C A L E N D A R                        --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1999-2018, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  This package extends Ada.Calendar to handle Hour, Minute, Second,
  33 --  Second_Duration and Day_Of_Week and Day_In_Year from Calendar.Time.
  34 --  Second_Duration precision depends on the target clock precision.
  35 --
  36 --  GNAT.Calendar provides the same kind of abstraction found in Ada.Calendar.
  37 --  It provides Split and Time_Of to build and split a Time data. And it
  38 --  provides accessor functions to get only one of Hour, Minute, Second,
  39 --  Second_Duration. Other functions are to access more advanced values like
  40 --  Day_Of_Week, Day_In_Year and Week_In_Year.
  41
  42 with Ada.Calendar.Formatting;
  43 with Interfaces.C;
  44
  45 package GNAT.Calendar is
  46
  47    type Day_Name is
  48      (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday);
  49    pragma Ordered (Day_Name);
  50
  51    subtype Hour_Number         is Natural range 0 .. 23;
  52    subtype Minute_Number       is Natural range 0 .. 59;
  53    subtype Second_Number       is Natural range 0 .. 59;
  54    subtype Second_Duration     is Ada.Calendar.Day_Duration range 0.0 .. 1.0;
  55    subtype Day_In_Year_Number  is Positive range 1 .. 366;
  56    subtype Week_In_Year_Number is Positive range 1 .. 53;
  57
  58    No_Time : constant Ada.Calendar.Time;
  59    --  A constant set to the first date that can be represented by the type
  60    --  Time. It can be used to indicate an uninitialized date.
  61
  62    function Hour       (Date : Ada.Calendar.Time) return Hour_Number;
  63    function Minute     (Date : Ada.Calendar.Time) return Minute_Number;
  64    function Second     (Date : Ada.Calendar.Time) return Second_Number;
  65    function Sub_Second (Date : Ada.Calendar.Time) return Second_Duration;
  66    --  Hour, Minute, Second and Sub_Second returns the complete time data for
  67    --  the Date (H:M:S.SS). See Ada.Calendar for Year, Month, Day accessors.
  68    --  Second_Duration precision depends on the target clock precision.
  69
  70    function Day_Of_Week (Date : Ada.Calendar.Time) return Day_Name;
  71    --  Return the day name
  72
  73    function Day_In_Year (Date : Ada.Calendar.Time) return Day_In_Year_Number;
  74    --  Return the day number in the year. (1st January is day 1 and 31st
  75    --  December is day 365 or 366 for leap year).
  76
  77    procedure Split
  78      (Date       : Ada.Calendar.Time;
  79       Year       : out Ada.Calendar.Year_Number;
  80       Month      : out Ada.Calendar.Month_Number;
  81       Day        : out Ada.Calendar.Day_Number;
  82       Hour       : out Hour_Number;
  83       Minute     : out Minute_Number;
  84       Second     : out Second_Number;
  85       Sub_Second : out Second_Duration);
  86    --  Split a standard Ada.Calendar.Time value in date data (Year, Month, Day)
  87    --  and Time data (Hour, Minute, Second, Sub_Second).
  88
  89    procedure Split_At_Locale
  90      (Date       : Ada.Calendar.Time;
  91       Year       : out Ada.Calendar.Year_Number;
  92       Month      : out Ada.Calendar.Month_Number;
  93       Day        : out Ada.Calendar.Day_Number;
  94       Hour       : out Hour_Number;
  95       Minute     : out Minute_Number;
  96       Second     : out Second_Number;
  97       Sub_Second : out Second_Duration);
  98    --  Split a standard Ada.Calendar.Time value in date data (Year, Month, Day)
  99    --  and Time data (Hour, Minute, Second, Sub_Second). This version of Split
 100    --  utilizes the time zone and DST bias of the locale (equivalent to Clock).
 101    --  Due to this simplified behavior, the implementation does not require
 102    --  expensive system calls on targets such as Windows.
 103    --  WARNING: Split_At_Locale is no longer aware of historic events and may
 104    --  produce inaccurate results over DST changes which occurred in the past.
 105
 106    function Time_Of
 107      (Year       : Ada.Calendar.Year_Number;
 108       Month      : Ada.Calendar.Month_Number;
 109       Day        : Ada.Calendar.Day_Number;
 110       Hour       : Hour_Number;
 111       Minute     : Minute_Number;
 112       Second     : Second_Number;
 113       Sub_Second : Second_Duration := 0.0) return Ada.Calendar.Time;
 114    --  Return an Ada.Calendar.Time data built from the date and time values
 115
 116    function Time_Of_At_Locale
 117      (Year       : Ada.Calendar.Year_Number;
 118       Month      : Ada.Calendar.Month_Number;
 119       Day        : Ada.Calendar.Day_Number;
 120       Hour       : Hour_Number;
 121       Minute     : Minute_Number;
 122       Second     : Second_Number;
 123       Sub_Second : Second_Duration := 0.0) return Ada.Calendar.Time;
 124    --  Return an Ada.Calendar.Time data built from the date and time values.
 125    --  This version of Time_Of utilizes the time zone and DST bias of the
 126    --  locale (equivalent to Clock). Due to this simplified behavior, the
 127    --  implementation does not require expensive system calls on targets such
 128    --  as Windows.
 129    --  WARNING: Split_At_Locale is no longer aware of historic events and may
 130    --  produce inaccurate results over DST changes which occurred in the past.
 131
 132    function Week_In_Year (Date : Ada.Calendar.Time) return Week_In_Year_Number;
 133    --  Return the week number as defined in ISO 8601. A week always starts on
 134    --  a Monday and the first week of a particular year is the one containing
 135    --  the first Thursday. A year may have 53 weeks when January 1st is a
 136    --  Wednesday and the year is leap or January 1st is a Thursday. Note that
 137    --  the last days of December may belong to the first week on the next year
 138    --  and conversely, the first days of January may belong to the last week
 139    --  of the last year.
 140
 141    procedure Year_Week_In_Year
 142      (Date : Ada.Calendar.Time;
 143       Year : out Ada.Calendar.Year_Number;
 144       Week : out Week_In_Year_Number);
 145    --  Return the week number as defined in ISO 8601 along with the year in
 146    --  which the week occurs.
 147
 148    --  C timeval conversion
 149
 150    --  C timeval represent a duration (used in Select for example). This
 151    --  structure is composed of a number of seconds and a number of micro
 152    --  seconds. The timeval structure is not exposed here because its
 153    --  definition is target dependent. Interface to C programs is done via a
 154    --  pointer to timeval structure.
 155
 156    type timeval is private;
 157
 158    function To_Duration (T : not null access timeval) return Duration;
 159    function To_Timeval  (D : Duration) return timeval;
 160
 161 private
 162    --  This is a dummy declaration that should be the largest possible timeval
 163    --  structure of all supported targets.
 164
 165    type timeval is array (1 .. 3) of Interfaces.C.long;
 166
 167    function Julian_Day
 168      (Year  : Ada.Calendar.Year_Number;
 169       Month : Ada.Calendar.Month_Number;
 170       Day   : Ada.Calendar.Day_Number) return Integer;
 171    --  Compute Julian day number
 172    --
 173    --  The code of this function is a modified version of algorithm 199 from
 174    --  the Collected Algorithms of the ACM. The author of algorithm 199 is
 175    --  Robert G. Tantzen.
 176
 177    No_Time : constant Ada.Calendar.Time :=
 178                Ada.Calendar.Formatting.Time_Of
 179                  (Ada.Calendar.Year_Number'First,
 180                   Ada.Calendar.Month_Number'First,
 181                   Ada.Calendar.Day_Number'First,
 182                   Time_Zone => 0);
 183    --  Use Time_Zone => 0 to be the same binary representation in any timezone
 184
 185 end GNAT.Calendar;