chrono.h revision 12037:d28054ac6ec9 
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
30NAMESPACE_BEGIN(pybind11)
31NAMESPACE_BEGIN(detail)
32
33template <typename type> class duration_caster {
34public:
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
99template <typename Duration> class type_caster<std::chrono::time_point<std::chrono::system_clock, Duration>> {
100public:
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        if (PyDateTime_Check(src.ptr())) {
110            std::tm cal;
111            cal.tm_sec   = PyDateTime_DATE_GET_SECOND(src.ptr());
112            cal.tm_min   = PyDateTime_DATE_GET_MINUTE(src.ptr());
113            cal.tm_hour  = PyDateTime_DATE_GET_HOUR(src.ptr());
114            cal.tm_mday  = PyDateTime_GET_DAY(src.ptr());
115            cal.tm_mon   = PyDateTime_GET_MONTH(src.ptr()) - 1;
116            cal.tm_year  = PyDateTime_GET_YEAR(src.ptr()) - 1900;
117            cal.tm_isdst = -1;
118
119            value = system_clock::from_time_t(std::mktime(&cal)) + microseconds(PyDateTime_DATE_GET_MICROSECOND(src.ptr()));
120            return true;
121        }
122        else return false;
123    }
124
125    static handle cast(const std::chrono::time_point<std::chrono::system_clock, Duration> &src, return_value_policy /* policy */, handle /* parent */) {
126        using namespace std::chrono;
127
128        // Lazy initialise the PyDateTime import
129        if (!PyDateTimeAPI) { PyDateTime_IMPORT; }
130
131        std::time_t tt = system_clock::to_time_t(src);
132        // this function uses static memory so it's best to copy it out asap just in case
133        // otherwise other code that is using localtime may break this (not just python code)
134        std::tm localtime = *std::localtime(&tt);
135
136        // Declare these special duration types so the conversions happen with the correct primitive types (int)
137        using us_t = duration<int, std::micro>;
138
139        return PyDateTime_FromDateAndTime(localtime.tm_year + 1900,
140                                          localtime.tm_mon + 1,
141                                          localtime.tm_mday,
142                                          localtime.tm_hour,
143                                          localtime.tm_min,
144                                          localtime.tm_sec,
145                                          (duration_cast<us_t>(src.time_since_epoch() % seconds(1))).count());
146    }
147    PYBIND11_TYPE_CASTER(type, _("datetime.datetime"));
148};
149
150// Other clocks that are not the system clock are not measured as datetime.datetime objects
151// since they are not measured on calendar time. So instead we just make them timedeltas
152// Or if they have passed us a time as a float we convert that
153template <typename Clock, typename Duration> class type_caster<std::chrono::time_point<Clock, Duration>>
154: public duration_caster<std::chrono::time_point<Clock, Duration>> {
155};
156
157template <typename Rep, typename Period> class type_caster<std::chrono::duration<Rep, Period>>
158: public duration_caster<std::chrono::duration<Rep, Period>> {
159};
160
161NAMESPACE_END(detail)
162NAMESPACE_END(pybind11)
163