sj::time_of_day::time_of_day(boost::posix_time::time_duration time,
boost::local_time::time_zone_ptr tz,
boost::optional<bool> dst)
: _time(time)
, _tz(tz)
, _dst(dst)
{
assert(time >= time_duration() && time < time_duration(hours(24)));
static time_duration zerodur = time_duration(hours(0));
// following code is only to check if dst parameter is neccessary
if (dst)
{
return;
}
if (tz->dst_offset() < zerodur)
{
std::stringstream ss;
ss << "irrational timezone: " << tz->std_zone_name()
<< " DST offset: " << tz->dst_offset();
throw std::invalid_argument(ss.str());
}
static date sampledate(2000, 1, 15);
ptime sampletime(sampledate, time);
time_duration tz_starttime = tz->dst_local_start_time(2000).time_of_day();
time_duration tz_endtime = tz->dst_local_end_time(2000).time_of_day();
ptime startsample(sampledate, tz_starttime);
if (startsample > sampletime)
{
startsample -= days(1);
}
ptime endsample(sampledate, tz_endtime);
if (endsample < sampletime)
{
endsample += days(1);
}
time_period tpd1(startsample, tz->dst_offset());
time_period tpd2(endsample - tz->dst_offset(), tz->dst_offset());
if (tpd1.contains(sampletime) || tpd2.contains(sampletime))
{
std::stringstream ss;
ss << "time_of_day(): dst setting is required for "
<< "tz: " << tz->std_zone_name() << " time: " << time;
throw std::invalid_argument(ss.str());
}
}
virtual int computePreference(const std::string& id,
boost::local_time::time_zone_ptr tz)
{
/*
* We implement here the following heuristic:
*
* If abbrev != name:
* preference = 6 (this seems to select 'standard' cities in USA)
* Otherwise,
* take first city of the following 'preferred' list:
* - Europe (5)
* - Asia (4),
* - Australia (3),
* - America (2)
* Otherwise, 1
*/
if (tz->std_zone_abbrev() != tz->std_zone_name())
return 6;
else {
if (boost::starts_with(id, "Europe/"))
return 5;
else if (boost::starts_with(id, "Australia/"))
return 4;
else if (boost::starts_with(id, "Asia/"))
return 3;
else if (boost::starts_with(id, "America/"))
return 2;
else
return 1;
}
}
