boost/date_time/local_time/local_date_time.hpp
#ifndef LOCAL_TIME_LOCAL_DATE_TIME_HPP__
#define LOCAL_TIME_LOCAL_DATE_TIME_HPP__
/* Copyright (c) 2003-2005 CrystalClear Software, Inc.
* Subject to the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
* Author: Jeff Garland, Bart Garst
* $Date: 2010-01-10 11:17:23 -0800 (Sun, 10 Jan 2010) $
*/
#include <string>
#include <iomanip>
#include <sstream>
#include <stdexcept>
#include <boost/shared_ptr.hpp>
#include <boost/throw_exception.hpp>
#include <boost/date_time/time.hpp>
#include <boost/date_time/posix_time/posix_time.hpp> //todo remove?
#include <boost/date_time/dst_rules.hpp>
#include <boost/date_time/time_zone_base.hpp>
#include <boost/date_time/special_defs.hpp>
#include <boost/date_time/time_resolution_traits.hpp> // absolute_value
namespace boost {
namespace local_time {
//! simple exception for reporting when STD or DST cannot be determined
struct ambiguous_result : public std::logic_error
{
ambiguous_result (std::string const& msg = std::string()) :
std::logic_error(std::string("Daylight Savings Results are ambiguous: " + msg)) {}
};
//! simple exception for when time label given cannot exist
struct time_label_invalid : public std::logic_error
{
time_label_invalid (std::string const& msg = std::string()) :
std::logic_error(std::string("Time label given is invalid: " + msg)) {}
};
struct dst_not_valid: public std::logic_error
{
dst_not_valid(std::string const& msg = std::string()) :
std::logic_error(std::string("is_dst flag does not match resulting dst for time label given: " + msg)) {}
};
//TODO: I think these should be in local_date_time_base and not
// necessarily brought into the namespace
using date_time::time_is_dst_result;
using date_time::is_in_dst;
using date_time::is_not_in_dst;
using date_time::ambiguous;
using date_time::invalid_time_label;
//! Representation of "wall-clock" time in a particular time zone
/*! Representation of "wall-clock" time in a particular time zone
* Local_date_time_base holds a time value (date and time offset from 00:00)
* along with a time zone. The time value is stored as UTC and conversions
* to wall clock time are made as needed. This approach allows for
* operations between wall-clock times in different time zones, and
* daylight savings time considerations, to be made. Time zones are
* required to be in the form of a boost::shared_ptr<time_zone_base>.
*/
template<class utc_time_=posix_time::ptime,
class tz_type=date_time::time_zone_base<utc_time_,char> >
class local_date_time_base : public date_time::base_time<utc_time_,
boost::posix_time::posix_time_system> {
public:
typedef utc_time_ utc_time_type;
typedef typename utc_time_type::time_duration_type time_duration_type;
typedef typename utc_time_type::date_type date_type;
typedef typename date_type::duration_type date_duration_type;
typedef typename utc_time_type::time_system_type time_system_type;
/*! This constructor interprets the passed time as a UTC time.
* So, for example, if the passed timezone is UTC-5 then the
* time will be adjusted back 5 hours. The time zone allows for
* automatic calculation of whether the particular time is adjusted for
* daylight savings, etc.
* If the time zone shared pointer is null then time stays unadjusted.
*@param t A UTC time
*@param tz Timezone for to adjust the UTC time to.
*/
local_date_time_base(utc_time_type t,
boost::shared_ptr<tz_type> tz) :
date_time::base_time<utc_time_type, time_system_type>(t),
zone_(tz)
{
// param was already utc so nothing more to do
}
/*! This constructs a local time -- the passed time information
* understood to be in the passed tz. The DST flag must be passed
* to indicate whether the time is in daylight savings or not.
* @throws -- time_label_invalid if the time passed does not exist in
* the given locale. The non-existent case occurs typically
* during the shift-back from daylight savings time. When
* the clock is shifted forward a range of times
* (2 am to 3 am in the US) is skipped and hence is invalid.
* @throws -- dst_not_valid if the DST flag is passed for a period
* where DST is not active.
*/
local_date_time_base(date_type d,
time_duration_type td,
boost::shared_ptr<tz_type> tz,
bool dst_flag) : //necessary for constr_adj()
date_time::base_time<utc_time_type,time_system_type>(construction_adjustment(utc_time_type(d, td), tz, dst_flag)),
zone_(tz)
{
if(tz != boost::shared_ptr<tz_type>() && tz->has_dst()){
// d & td are already local so we use them
time_is_dst_result result = check_dst(d, td, tz);
bool in_dst = (result == is_in_dst); // less processing than is_dst()
// ambig occurs at end, invalid at start
if(result == invalid_time_label){
// Ex: 2:15am local on trans-in day in nyc, dst_flag irrelevant
std::ostringstream ss;
ss << "time given: " << d << ' ' << td;
boost::throw_exception(time_label_invalid(ss.str()));
}
else if(result != ambiguous && in_dst != dst_flag){
// is dst_flag accurate?
// Ex: false flag in NYC in June
std::ostringstream ss;
ss.setf(std::ios_base::boolalpha);
ss << "flag given: dst=" << dst_flag << ", dst calculated: dst=" << in_dst;
boost::throw_exception(dst_not_valid(ss.str()));
}
// everything checks out and conversion to utc already done
}
}
//TODO maybe not the right set...Ignore the last 2 for now...
enum DST_CALC_OPTIONS { EXCEPTION_ON_ERROR, NOT_DATE_TIME_ON_ERROR };
//ASSUME_DST_ON_ERROR, ASSUME_NOT_DST_ON_ERROR };
/*! This constructs a local time -- the passed time information
* understood to be in the passed tz. The DST flag is calculated
* according to the specified rule.
*/
local_date_time_base(date_type d,
time_duration_type td,
boost::shared_ptr<tz_type> tz,
DST_CALC_OPTIONS calc_option) :
// dummy value - time_ is set in constructor code
date_time::base_time<utc_time_type,time_system_type>(utc_time_type(d,td)),
zone_(tz)
{
time_is_dst_result result = check_dst(d, td, tz);
if(result == ambiguous) {
if(calc_option == EXCEPTION_ON_ERROR){
std::ostringstream ss;
ss << "time given: " << d << ' ' << td;
boost::throw_exception(ambiguous_result(ss.str()));
}
else{ // NADT on error
this->time_ = posix_time::posix_time_system::get_time_rep(date_type(date_time::not_a_date_time), time_duration_type(date_time::not_a_date_time));
}
}
else if(result == invalid_time_label){
if(calc_option == EXCEPTION_ON_ERROR){
std::ostringstream ss;
ss << "time given: " << d << ' ' << td;
boost::throw_exception(time_label_invalid(ss.str()));
}
else{ // NADT on error
this->time_ = posix_time::posix_time_system::get_time_rep(date_type(date_time::not_a_date_time), time_duration_type(date_time::not_a_date_time));
}
}
else if(result == is_in_dst){
utc_time_type t =
construction_adjustment(utc_time_type(d, td), tz, true);
this->time_ = posix_time::posix_time_system::get_time_rep(t.date(),
t.time_of_day());
}
else{
utc_time_type t =
construction_adjustment(utc_time_type(d, td), tz, false);
this->time_ = posix_time::posix_time_system::get_time_rep(t.date(),
t.time_of_day());
}
}
//! Determines if given time label is in daylight savings for given zone
/*! Determines if given time label is in daylight savings for given zone.
* Takes a date and time_duration representing a local time, along
* with time zone, and returns a time_is_dst_result object as result.
*/
static time_is_dst_result check_dst(date_type d,
time_duration_type td,
boost::shared_ptr<tz_type> tz)
{
if(tz != boost::shared_ptr<tz_type>() && tz->has_dst()) {
typedef typename date_time::dst_calculator<date_type, time_duration_type> dst_calculator;
return dst_calculator::local_is_dst(
d, td,
tz->dst_local_start_time(d.year()).date(),
tz->dst_local_start_time(d.year()).time_of_day(),
tz->dst_local_end_time(d.year()).date(),
tz->dst_local_end_time(d.year()).time_of_day(),
tz->dst_offset()
);
}
else{
return is_not_in_dst;
}
}
//! Simple destructor, releases time zone if last referrer
~local_date_time_base() {};
//! Copy constructor
local_date_time_base(const local_date_time_base& rhs) :
date_time::base_time<utc_time_type, time_system_type>(rhs),
zone_(rhs.zone_)
{}
//! Special values constructor
explicit local_date_time_base(const boost::date_time::special_values sv,
boost::shared_ptr<tz_type> tz = boost::shared_ptr<tz_type>()) :
date_time::base_time<utc_time_type, time_system_type>(utc_time_type(sv)),
zone_(tz)
{}
//! returns time zone associated with calling instance
boost::shared_ptr<tz_type> zone() const
{
return zone_;
}
//! returns false is time_zone is NULL and if time value is a special_value
bool is_dst() const
{
if(zone_ != boost::shared_ptr<tz_type>() && zone_->has_dst() && !this->is_special()) {
// check_dst takes a local time, *this is utc
utc_time_type lt(this->time_);
lt += zone_->base_utc_offset();
// dst_offset only needs to be considered with ambiguous time labels
// make that adjustment there
switch(check_dst(lt.date(), lt.time_of_day(), zone_)){
case is_not_in_dst:
return false;
case is_in_dst:
return true;
case ambiguous:
if(lt + zone_->dst_offset() < zone_->dst_local_end_time(lt.date().year())) {
return true;
}
break;
case invalid_time_label:
if(lt >= zone_->dst_local_start_time(lt.date().year())) {
return true;
}
break;
}
}
return false;
}
//! Returns object's time value as a utc representation
utc_time_type utc_time() const
{
return utc_time_type(this->time_);
}
//! Returns object's time value as a local representation
utc_time_type local_time() const
{
if(zone_ != boost::shared_ptr<tz_type>()){
utc_time_type lt = this->utc_time() + zone_->base_utc_offset();
if (is_dst()) {
lt += zone_->dst_offset();
}
return lt;
}
return utc_time_type(this->time_);
}
//! Returns string in the form "2003-Aug-20 05:00:00 EDT"
/*! Returns string in the form "2003-Aug-20 05:00:00 EDT". If
* time_zone is NULL the time zone abbreviation will be "UTC". The time
* zone abbrev will not be included if calling object is a special_value*/
std::string to_string() const
{
//TODO is this a temporary function ???
std::ostringstream ss;
if(this->is_special()){
ss << utc_time();
return ss.str();
}
if(zone_ == boost::shared_ptr<tz_type>()) {
ss << utc_time() << " UTC";
return ss.str();
}
bool is_dst_ = is_dst();
utc_time_type lt = this->utc_time() + zone_->base_utc_offset();
if (is_dst_) {
lt += zone_->dst_offset();
}
ss << local_time() << " ";
if (is_dst()) {
ss << zone_->dst_zone_abbrev();
}
else {
ss << zone_->std_zone_abbrev();
}
return ss.str();
}
/*! returns a local_date_time_base in the given time zone with the
* optional time_duration added. */
local_date_time_base local_time_in(boost::shared_ptr<tz_type> new_tz,
time_duration_type td=time_duration_type(0,0,0)) const
{
return local_date_time_base(utc_time_type(this->time_) + td, new_tz);
}
//! Returns name of associated time zone or "Coordinated Universal Time".
/*! Optional bool parameter will return time zone as an offset
* (ie "+07:00" extended iso format). Empty string is returned for
* classes that do not use a time_zone */
std::string zone_name(bool as_offset=false) const
{
if(zone_ == boost::shared_ptr<tz_type>()) {
if(as_offset) {
return std::string("Z");
}
else {
return std::string("Coordinated Universal Time");
}
}
if (is_dst()) {
if(as_offset) {
time_duration_type td = zone_->base_utc_offset();
td += zone_->dst_offset();
return zone_as_offset(td, ":");
}
else {
return zone_->dst_zone_name();
}
}
else {
if(as_offset) {
time_duration_type td = zone_->base_utc_offset();
return zone_as_offset(td, ":");
}
else {
return zone_->std_zone_name();
}
}
}
//! Returns abbreviation of associated time zone or "UTC".
/*! Optional bool parameter will return time zone as an offset
* (ie "+0700" iso format). Empty string is returned for classes
* that do not use a time_zone */
std::string zone_abbrev(bool as_offset=false) const
{
if(zone_ == boost::shared_ptr<tz_type>()) {
if(as_offset) {
return std::string("Z");
}
else {
return std::string("UTC");
}
}
if (is_dst()) {
if(as_offset) {
time_duration_type td = zone_->base_utc_offset();
td += zone_->dst_offset();
return zone_as_offset(td, "");
}
else {
return zone_->dst_zone_abbrev();
}
}
else {
if(as_offset) {
time_duration_type td = zone_->base_utc_offset();
return zone_as_offset(td, "");
}
else {
return zone_->std_zone_abbrev();
}
}
}
//! returns a posix_time_zone string for the associated time_zone. If no time_zone, "UTC+00" is returned.
std::string zone_as_posix_string() const
{
if(zone_ == shared_ptr<tz_type>()) {
return std::string("UTC+00");
}
return zone_->to_posix_string();
}
//! Equality comparison operator
/*bool operator==(const date_time::base_time<boost::posix_time::ptime,boost::posix_time::posix_time_system>& rhs) const
{ // fails due to rhs.time_ being protected
return date_time::base_time<boost::posix_time::ptime,boost::posix_time::posix_time_system>::operator==(rhs);
//return this->time_ == rhs.time_;
}*/
//! Equality comparison operator
bool operator==(const local_date_time_base& rhs) const
{
return time_system_type::is_equal(this->time_, rhs.time_);
}
//! Non-Equality comparison operator
bool operator!=(const local_date_time_base& rhs) const
{
return !(*this == rhs);
}
//! Less than comparison operator
bool operator<(const local_date_time_base& rhs) const
{
return time_system_type::is_less(this->time_, rhs.time_);
}
//! Less than or equal to comparison operator
bool operator<=(const local_date_time_base& rhs) const
{
return (*this < rhs || *this == rhs);
}
//! Greater than comparison operator
bool operator>(const local_date_time_base& rhs) const
{
return !(*this <= rhs);
}
//! Greater than or equal to comparison operator
bool operator>=(const local_date_time_base& rhs) const
{
return (*this > rhs || *this == rhs);
}
//! Local_date_time + date_duration
local_date_time_base operator+(const date_duration_type& dd) const
{
return local_date_time_base(time_system_type::add_days(this->time_,dd), zone_);
}
//! Local_date_time += date_duration
local_date_time_base operator+=(const date_duration_type& dd)
{
this->time_ = time_system_type::add_days(this->time_,dd);
return *this;
}
//! Local_date_time - date_duration
local_date_time_base operator-(const date_duration_type& dd) const
{
return local_date_time_base(time_system_type::subtract_days(this->time_,dd), zone_);
}
//! Local_date_time -= date_duration
local_date_time_base operator-=(const date_duration_type& dd)
{
this->time_ = time_system_type::subtract_days(this->time_,dd);
return *this;
}
//! Local_date_time + time_duration
local_date_time_base operator+(const time_duration_type& td) const
{
return local_date_time_base(time_system_type::add_time_duration(this->time_,td), zone_);
}
//! Local_date_time += time_duration
local_date_time_base operator+=(const time_duration_type& td)
{
this->time_ = time_system_type::add_time_duration(this->time_,td);
return *this;
}
//! Local_date_time - time_duration
local_date_time_base operator-(const time_duration_type& td) const
{
return local_date_time_base(time_system_type::subtract_time_duration(this->time_,td), zone_);
}
//! Local_date_time -= time_duration
local_date_time_base operator-=(const time_duration_type& td)
{
this->time_ = time_system_type::subtract_time_duration(this->time_,td);
return *this;
}
//! local_date_time -= local_date_time --> time_duration_type
time_duration_type operator-(const local_date_time_base& rhs) const
{
return utc_time_type(this->time_) - utc_time_type(rhs.time_);
}
private:
boost::shared_ptr<tz_type> zone_;
//bool is_dst_;
/*! Adjust the passed in time to UTC?
*/
utc_time_type construction_adjustment(utc_time_type t,
boost::shared_ptr<tz_type> z,
bool dst_flag)
{
if(z != boost::shared_ptr<tz_type>()) {
if(dst_flag && z->has_dst()) {
t -= z->dst_offset();
} // else no adjust
t -= z->base_utc_offset();
}
return t;
}
/*! Simple formatting code -- todo remove this?
*/
std::string zone_as_offset(const time_duration_type& td,
const std::string& separator) const
{
std::ostringstream ss;
if(td.is_negative()) {
// a negative duration is represented as "-[h]h:mm"
// we require two digits for the hour. A positive duration
// with the %H flag will always give two digits
ss << "-";
}
else {
ss << "+";
}
ss << std::setw(2) << std::setfill('0')
<< date_time::absolute_value(td.hours())
<< separator
<< std::setw(2) << std::setfill('0')
<< date_time::absolute_value(td.minutes());
return ss.str();
}
};
//!Use the default parameters to define local_date_time
typedef local_date_time_base<> local_date_time;
} }
#endif