ext/pybind11/include/pybind11/chrono.h

   1 /*
   2     pybind11/chrono.h: Transparent conversion between std::chrono and python's datetime
   3
   4     Copyright (c) 2016 Trent Houliston <trent@houliston.me> and
   5                        Wenzel Jakob <wenzel.jakob@epfl.ch>
   6
   7     All rights reserved. Use of this source code is governed by a
   8     BSD-style license that can be found in the LICENSE file.
   9 */
  10
  11 #pragma once
  12
  13 #include "pybind11.h"
  14 #include <cmath>
  15 #include <ctime>
  16 #include <chrono>
  17 #include <datetime.h>
  18
  19 // Backport the PyDateTime_DELTA functions from Python3.3 if required
  20 #ifndef PyDateTime_DELTA_GET_DAYS
  21 #define PyDateTime_DELTA_GET_DAYS(o)         (((PyDateTime_Delta*)o)->days)
  22 #endif
  23 #ifndef PyDateTime_DELTA_GET_SECONDS
  24 #define PyDateTime_DELTA_GET_SECONDS(o)      (((PyDateTime_Delta*)o)->seconds)
  25 #endif
  26 #ifndef PyDateTime_DELTA_GET_MICROSECONDS
  27 #define PyDateTime_DELTA_GET_MICROSECONDS(o) (((PyDateTime_Delta*)o)->microseconds)
  28 #endif
  29
  30 NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
  31 NAMESPACE_BEGIN(detail)
  32
  33 template <typename type> class duration_caster {
  34 public:
  35     typedef typename type::rep rep;
  36     typedef typename type::period period;
  37
  38     typedef std::chrono::duration<uint_fast32_t, std::ratio<86400>> days;
  39
  40     bool load(handle src, bool) {
  41         using namespace std::chrono;
  42
  43         // Lazy initialise the PyDateTime import
  44         if (!PyDateTimeAPI) { PyDateTime_IMPORT; }
  45
  46         if (!src) return false;
  47         // If invoked with datetime.delta object
  48         if (PyDelta_Check(src.ptr())) {
  49             value = type(duration_cast<duration<rep, period>>(
  50                   days(PyDateTime_DELTA_GET_DAYS(src.ptr()))
  51                 + seconds(PyDateTime_DELTA_GET_SECONDS(src.ptr()))
  52                 + microseconds(PyDateTime_DELTA_GET_MICROSECONDS(src.ptr()))));
  53             return true;
  54         }
  55         // If invoked with a float we assume it is seconds and convert
  56         else if (PyFloat_Check(src.ptr())) {
  57             value = type(duration_cast<duration<rep, period>>(duration<double>(PyFloat_AsDouble(src.ptr()))));
  58             return true;
  59         }
  60         else return false;
  61     }
  62
  63     // If this is a duration just return it back
  64     static const std::chrono::duration<rep, period>& get_duration(const std::chrono::duration<rep, period> &src) {
  65         return src;
  66     }
  67
  68     // If this is a time_point get the time_since_epoch
  69     template <typename Clock> static std::chrono::duration<rep, period> get_duration(const std::chrono::time_point<Clock, std::chrono::duration<rep, period>> &src) {
  70         return src.time_since_epoch();
  71     }
  72
  73     static handle cast(const type &src, return_value_policy /* policy */, handle /* parent */) {
  74         using namespace std::chrono;
  75
  76         // Use overloaded function to get our duration from our source
  77         // Works out if it is a duration or time_point and get the duration
  78         auto d = get_duration(src);
  79
  80         // Lazy initialise the PyDateTime import
  81         if (!PyDateTimeAPI) { PyDateTime_IMPORT; }
  82
  83         // Declare these special duration types so the conversions happen with the correct primitive types (int)
  84         using dd_t = duration<int, std::ratio<86400>>;
  85         using ss_t = duration<int, std::ratio<1>>;
  86         using us_t = duration<int, std::micro>;
  87
  88         auto dd = duration_cast<dd_t>(d);
  89         auto subd = d - dd;
  90         auto ss = duration_cast<ss_t>(subd);
  91         auto us = duration_cast<us_t>(subd - ss);
  92         return PyDelta_FromDSU(dd.count(), ss.count(), us.count());
  93     }
  94
  95     PYBIND11_TYPE_CASTER(type, _("datetime.timedelta"));
  96 };
  97
  98 // This is for casting times on the system clock into datetime.datetime instances
  99 template <typename Duration> class type_caster<std::chrono::time_point<std::chrono::system_clock, Duration>> {
 100 public:
 101     typedef std::chrono::time_point<std::chrono::system_clock, Duration> type;
 102     bool load(handle src, bool) {
 103         using namespace std::chrono;
 104
 105         // Lazy initialise the PyDateTime import
 106         if (!PyDateTimeAPI) { PyDateTime_IMPORT; }
 107
 108         if (!src) return false;
 109
 110         std::tm cal;
 111         microseconds msecs;
 112
 113         if (PyDateTime_Check(src.ptr())) {
 114             cal.tm_sec   = PyDateTime_DATE_GET_SECOND(src.ptr());
 115             cal.tm_min   = PyDateTime_DATE_GET_MINUTE(src.ptr());
 116             cal.tm_hour  = PyDateTime_DATE_GET_HOUR(src.ptr());
 117             cal.tm_mday  = PyDateTime_GET_DAY(src.ptr());
 118             cal.tm_mon   = PyDateTime_GET_MONTH(src.ptr()) - 1;
 119             cal.tm_year  = PyDateTime_GET_YEAR(src.ptr()) - 1900;
 120             cal.tm_isdst = -1;
 121             msecs        = microseconds(PyDateTime_DATE_GET_MICROSECOND(src.ptr()));
 122         } else if (PyDate_Check(src.ptr())) {
 123             cal.tm_sec   = 0;
 124             cal.tm_min   = 0;
 125             cal.tm_hour  = 0;
 126             cal.tm_mday  = PyDateTime_GET_DAY(src.ptr());
 127             cal.tm_mon   = PyDateTime_GET_MONTH(src.ptr()) - 1;
 128             cal.tm_year  = PyDateTime_GET_YEAR(src.ptr()) - 1900;
 129             cal.tm_isdst = -1;
 130             msecs        = microseconds(0);
 131         } else if (PyTime_Check(src.ptr())) {
 132             cal.tm_sec   = PyDateTime_TIME_GET_SECOND(src.ptr());
 133             cal.tm_min   = PyDateTime_TIME_GET_MINUTE(src.ptr());
 134             cal.tm_hour  = PyDateTime_TIME_GET_HOUR(src.ptr());
 135             cal.tm_mday  = 1;   // This date (day, month, year) = (1, 0, 70)
 136             cal.tm_mon   = 0;   // represents 1-Jan-1970, which is the first
 137             cal.tm_year  = 70;  // earliest available date for Python's datetime
 138             cal.tm_isdst = -1;
 139             msecs        = microseconds(PyDateTime_TIME_GET_MICROSECOND(src.ptr()));
 140         }
 141         else return false;
 142
 143         value = system_clock::from_time_t(std::mktime(&cal)) + msecs;
 144         return true;
 145     }
 146
 147     static handle cast(const std::chrono::time_point<std::chrono::system_clock, Duration> &src, return_value_policy /* policy */, handle /* parent */) {
 148         using namespace std::chrono;
 149
 150         // Lazy initialise the PyDateTime import
 151         if (!PyDateTimeAPI) { PyDateTime_IMPORT; }
 152
 153         std::time_t tt = system_clock::to_time_t(time_point_cast<system_clock::duration>(src));
 154         // this function uses static memory so it's best to copy it out asap just in case
 155         // otherwise other code that is using localtime may break this (not just python code)
 156         std::tm localtime = *std::localtime(&tt);
 157
 158         // Declare these special duration types so the conversions happen with the correct primitive types (int)
 159         using us_t = duration<int, std::micro>;
 160
 161         return PyDateTime_FromDateAndTime(localtime.tm_year + 1900,
 162                                           localtime.tm_mon + 1,
 163                                           localtime.tm_mday,
 164                                           localtime.tm_hour,
 165                                           localtime.tm_min,
 166                                           localtime.tm_sec,
 167                                           (duration_cast<us_t>(src.time_since_epoch() % seconds(1))).count());
 168     }
 169     PYBIND11_TYPE_CASTER(type, _("datetime.datetime"));
 170 };
 171
 172 // Other clocks that are not the system clock are not measured as datetime.datetime objects
 173 // since they are not measured on calendar time. So instead we just make them timedeltas
 174 // Or if they have passed us a time as a float we convert that
 175 template <typename Clock, typename Duration> class type_caster<std::chrono::time_point<Clock, Duration>>
 176 : public duration_caster<std::chrono::time_point<Clock, Duration>> {
 177 };
 178
 179 template <typename Rep, typename Period> class type_caster<std::chrono::duration<Rep, Period>>
 180 : public duration_caster<std::chrono::duration<Rep, Period>> {
 181 };
 182
 183 NAMESPACE_END(detail)
 184 NAMESPACE_END(PYBIND11_NAMESPACE)