artstime.h

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/* Copyright (C) 2020
 * Richard Larsson <larsson@mps.mpg.de>
 * 
 * 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, 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 * USA. */

#ifndef ARTSTIME_H
#define ARTSTIME_H

#include <chrono>
#include <cmath>

#include "array.h"
#include "mystring.h"

using TimeStep = std::chrono::duration<Numeric>;

class Time {
private:
  std::chrono::system_clock::time_point mtime;

public:
  using InternalTimeStep = decltype(mtime)::duration;
  
  // Version will be updated when C++20 datetime is available... Version 1 will still assume local time at that time
  Index Version() const noexcept {return 1;}
  
  // Construction
  Time() : mtime(std::chrono::system_clock::now()) {}
  explicit Time(std::time_t t) : mtime(std::chrono::system_clock::from_time_t(t)) {}
  explicit Time(std::tm t) : Time(std::mktime(&t)) {}
  
  // Data
  const std::chrono::system_clock::time_point& Data() const {return mtime;}
  
  // Conversions
  std::time_t toTimeT() const {return std::chrono::system_clock::to_time_t(mtime);}
  std::tm toStruct() const {std::time_t x=toTimeT();  std::tm* y = std::localtime(&x); return *y;}
  std::tm toGMTStruct() const {std::time_t x=toTimeT();  std::tm* y = std::gmtime(&x); return *y;}
  TimeStep seconds_into_day() const {std::tm x = toStruct(); return TimeStep(x.tm_hour*3600 + x.tm_min*60 + x.tm_sec + PartOfSecond());}
  InternalTimeStep EpochTime() const {return mtime.time_since_epoch();}
  
  // Operations
  InternalTimeStep operator-(const Time& t) const {return mtime - t.mtime;}
  bool operator<(const Time& t) const {return mtime < t.mtime;}
  bool operator==(const Time& t) const {return mtime == t.mtime;}
  template <typename T, typename R> Time& operator+=(const std::chrono::duration<T, R>& dt) {mtime += std::chrono::duration_cast<InternalTimeStep>(dt); return *this;}
  template <typename T, typename R> Time& operator-=(const std::chrono::duration<T, R>& dt) {mtime -= std::chrono::duration_cast<InternalTimeStep>(dt); return *this;}
  template <typename T, typename R> Time operator+(const std::chrono::duration<T, R>& dt) const {return (Time(*this) += dt);}
  template <typename T, typename R> Time operator-(const std::chrono::duration<T, R>& dt) const {return (Time(*this) -= dt);}
  
  // helpers
  Numeric Seconds() const {return std::chrono::duration_cast<TimeStep>(mtime.time_since_epoch()).count();}
  void Seconds(Numeric x) {operator+=(TimeStep(x - Seconds()));}
  Numeric PartOfSecond() const {return std::fmod(Seconds(), 1.0);}
}; // Time

using ArrayOfTime = Array<Time>;

using ArrayOfArrayOfTime = Array<ArrayOfTime>;

std::ostream& operator<<(std::ostream& os, const Time& t);

std::istream& operator>>(std::istream& is, Time& t);

inline std::ostream& operator<<(std::ostream& os, const TimeStep& dt) {return os << dt.count() << " seconds";}

Time next_even(const Time& t, const TimeStep& dt);

ArrayOfIndex time_steps(const ArrayOfTime& times, const String& step);

Time mean_time(const ArrayOfTime& ts, Index s=0, Index e=-1);

#endif  // ARTSTIME_H