datetime.hpp

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/*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2024 Denis Corbin
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// to contact the author, see the AUTHOR file
/*********************************************************************/
 
 
#ifndef DATETIME_HPP
#define DATETIME_HPP
 
extern "C"
{
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
 
#if HAVE_UTIME_H
#include <utime.h>
#endif
 
#if HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
 
} // end extern "C"
 
#include "../my_config.h"
#include "infinint.hpp"
 
namespace libdar
{
 
    class archive_version;
    class generic_file;
 
    class datetime
    {
    public:
        // time units must be sorted: the first is the smallest step, last is the largest increment.
        // this makes the comparison operators (<, >, <=, >=,...) become naturally defined on that type
    enum time_unit { tu_nanosecond, tu_microsecond, tu_second };
 
    datetime(const infinint & value = 0) { val = value; uni = tu_second; };
 
 
    datetime(time_t second, time_t subsec, time_unit unit);
 
    datetime(generic_file &x, archive_version ver);
 
    datetime(const datetime & ref) = default;
    datetime(datetime && ref) noexcept = default;
    datetime & operator = (const datetime & ref) = default;
    datetime & operator = (datetime && ref) noexcept = default;
    ~datetime() = default;
 
 
        // comparison operators
 
    bool operator < (const datetime & ref) const;
    bool operator == (const datetime & ref) const;
    bool operator != (const datetime & ref) const { return ! (*this == ref); };
    bool operator >= (const datetime & ref) const { return ! (*this < ref); };
    bool operator > (const datetime & ref) const { return ref < *this; };
    bool operator <= (const datetime & ref) const { return ref >= *this; };
 
        // arithmetic on time
    void operator -= (const datetime & ref);
    void operator += (const datetime & ref);
    datetime operator - (const datetime & ref) const { datetime tmp(*this); tmp -= ref; return tmp; };
    datetime operator + (const datetime & ref) const { datetime tmp(*this); tmp += ref; return tmp; };
 
    bool loose_equal(const datetime & ref) const;
 
    datetime loose_diff(const datetime & ref) const;
 
    infinint get_second_value() const { infinint sec, sub; get_value(sec, sub, uni); return sec; };
 
    infinint get_subsecond_value(time_unit unit) const;
 
    time_unit get_unit() const { return uni; };
 
 
    bool get_value(time_t & second, time_t & subsecond, time_unit unit) const;
 
 
    void dump(generic_file &x) const;
 
    void read(generic_file &f, archive_version ver);
 
    bool is_null() const { return val.is_zero(); };
 
    bool is_integer_second() const { return (uni == tu_second); };
 
    infinint get_storage_size() const;
 
    void nullify() { val = 0; uni = tu_second ; };
 
    private:
        // the date must not be stored as a single integer
        // to avoid reducing the possible addressable dates
        // when compiling using  32 or 64 bits integer in place
        // of infinint. The fraction cannot handle smaller unit
        // than nanosecond if using 32 bits integer.
 
    infinint val;  //< the date expressed in the "uni" time unit
    time_unit uni; //< the time unit used to store the subsecond fraction of the timestamp.
 
    void reduce_to_largest_unit() const;
    void get_value(infinint & sec, infinint & sub, time_unit unit) const;
    void build(const infinint & sec, const infinint & sub, time_unit unit);
 
    static time_unit min(time_unit a, time_unit b);
    static time_unit max(time_unit a, time_unit b);
    static const char time_unit_to_char(time_unit a);
    static time_unit char_to_time_unit(const char a);
 
 
    static const infinint & get_scaling_factor(time_unit source, time_unit dest);
 
    };
 
    extern archive_version db2archive_version(unsigned char db_version);
 
 
 
} // end of namespace
 
#endif