From 6ddfd1e090de6b5f1d1a14f7c51790275bff5818 Mon Sep 17 00:00:00 2001
From: Trent Houliston <trent@houliston.me>
Date: Thu, 25 Aug 2016 19:59:41 +1000
Subject: [PATCH] Add in casts for c++11s chrono classes to pythons datetime

---
 include/pybind11/cast.h   | 109 ++++++++++++++++++++++++++++++++++++++
 include/pybind11/common.h |   1 +
 2 files changed, 110 insertions(+)

diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index b885298a..4a0c703a 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -472,6 +472,115 @@ public:
     PYBIND11_TYPE_CASTER(bool, _("bool"));
 };
 
+template <typename Rep, typename Period> class type_caster<std::chrono::duration<Rep, Period>> {
+public:
+    typedef std::chrono::duration<Rep, Period> type;
+    typedef std::chrono::duration<std::chrono::hours::rep, std::ratio<86400>> days;
+
+    bool load(handle src, bool) {
+        using namespace std::chrono;
+        PyDateTime_IMPORT;
+
+        if (!src) return false;
+        if (PyDelta_Check(src.ptr())) {
+            const PyDateTime_Delta* delta = reinterpret_cast<PyDateTime_Delta*>(src.ptr());
+            value = duration_cast<duration<Rep, Period>>(
+                  days(delta->days)
+                + seconds(delta->seconds)
+                + microseconds(delta->microseconds));
+            return true;
+        }
+        else return false;
+    }
+
+    static handle cast(const std::chrono::duration<Rep, Period> &src, return_value_policy /* policy */, handle /* parent */) {
+        using namespace std::chrono;
+        PyDateTime_IMPORT;
+
+        int dd = duration_cast<days>(src).count();
+        int ss = duration_cast<seconds>(src % days(1)).count();
+        int us = duration_cast<microseconds>(src % seconds(1)).count();
+
+        return PyDelta_FromDSU(dd, ss, us);
+    }
+    PYBIND11_TYPE_CASTER(type, _("datetime.timedelta"));
+};
+
+template <typename Duration> class type_caster<std::chrono::time_point<std::chrono::system_clock, Duration>> {
+public:
+    typedef std::chrono::time_point<std::chrono::system_clock, Duration> type;
+    bool load(handle src, bool) {
+        using namespace std::chrono;
+        PyDateTime_IMPORT;
+
+        if (!src) return false;
+        if (PyDateTime_Check(src.ptr())) {
+            std::tm cal;
+            cal.tm_sec   = PyDateTime_DATE_GET_SECOND(src.ptr());
+            cal.tm_min   = PyDateTime_DATE_GET_MINUTE(src.ptr());
+            cal.tm_hour  = PyDateTime_DATE_GET_HOUR(src.ptr());
+            cal.tm_mday  = PyDateTime_GET_DAY(src.ptr());
+            cal.tm_mon   = PyDateTime_GET_MONTH(src.ptr()) - 1;
+            cal.tm_year  = PyDateTime_GET_YEAR(src.ptr());
+            cal.tm_isdst = -1;
+
+            value = system_clock::from_time_t(mktime(&cal));
+            return true;
+        }
+        else return false;
+    }
+
+    static handle cast(const std::chrono::time_point<std::chrono::system_clock, Duration> &src, return_value_policy /* policy */, handle /* parent */) {
+        using namespace std::chrono;
+        PyDateTime_IMPORT;
+
+        time_t tt = system_clock::to_time_t(src);
+        tm *ltime = localtime(&tt); // this function uses static memory so it's best
+        tm localtime = *ltime;       // to copy it out asap just in case
+
+        return PyDateTime_FromDateAndTime(localtime.tm_year, localtime.tm_mon + 1
+                                          , localtime.tm_mday
+                                          , localtime.tm_hour
+                                          , localtime.tm_min
+                                          , localtime.tm_sec
+                                          , (duration_cast<microseconds>(src.time_since_epoch()) % seconds(1)).count());
+    }
+    PYBIND11_TYPE_CASTER(type, _("datetime.datetime"));
+};
+
+template <typename Clock, typename Duration> class type_caster<std::chrono::time_point<Clock, Duration>> {
+public:
+    typedef std::chrono::time_point<Clock, Duration> type;
+    bool load(handle src, bool) {
+        using namespace std::chrono;
+        PyDateTime_IMPORT;
+
+        if (!src) return false;
+        if (PyTime_Check(src.ptr())) {
+            value = type(duration_cast<Duration>(
+                   hours(PyDateTime_TIME_GET_HOUR(src.ptr()))
+                 + minutes(PyDateTime_TIME_GET_MINUTE(src.ptr()))
+                 + seconds(PyDateTime_TIME_GET_SECOND(src.ptr()))
+                 + microseconds(PyDateTime_TIME_GET_MICROSECOND(src.ptr()))
+            ));
+            return true;
+        }
+        else return false;
+    }
+
+    static handle cast(const std::chrono::time_point<Clock, Duration> &src, return_value_policy /* policy */, handle /* parent */) {
+        using namespace std::chrono;
+        PyDateTime_IMPORT;
+
+        Duration d = src.time_since_epoch();
+        return PyTime_FromTime(duration_cast<hours>(d).count()
+                               , duration_cast<minutes>(d % hours(1)).count()
+                               , duration_cast<seconds>(d % minutes(1)).count()
+                               , duration_cast<microseconds>(d % seconds(1)).count());
+    }
+    PYBIND11_TYPE_CASTER(type, _("datetime.time"));
+};
+
 template <> class type_caster<std::string> {
 public:
     bool load(handle src, bool) {
diff --git a/include/pybind11/common.h b/include/pybind11/common.h
index fd65fe76..c1287daf 100644
--- a/include/pybind11/common.h
+++ b/include/pybind11/common.h
@@ -46,6 +46,7 @@
 #endif
 
 #include <Python.h>
+#include <datetime.h>
 #include <frameobject.h>
 #include <pythread.h>