/usr/include/boost/date_time
Edit: /usr/include/boost/date_time/dst_rules.hpp (15401B)
#ifndef DATE_TIME_DST_RULES_HPP__
#define DATE_TIME_DST_RULES_HPP__
/* Copyright (c) 2002,2003, 2007 CrystalClear Software, Inc.
* Use, modification and distribution is 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
* $Date$
*/
/*! @file dst_rules.hpp
Contains template class to provide static dst rule calculations
*/
#include "boost/date_time/date_generators.hpp"
#include "boost/date_time/period.hpp"
#include "boost/date_time/date_defs.hpp"
#include
namespace boost {
namespace date_time {
enum time_is_dst_result {is_not_in_dst, is_in_dst,
ambiguous, invalid_time_label};
//! Dynamic class used to caluclate dst transition information
template
class dst_calculator
{
public:
typedef time_duration_type_ time_duration_type;
typedef date_type_ date_type;
//! Check the local time offset when on dst start day
/*! On this dst transition, the time label between
* the transition boundary and the boudary + the offset
* are invalid times. If before the boundary then still
* not in dst.
*@param time_of_day Time offset in the day for the local time
*@param dst_start_offset_minutes Local day offset for start of dst
*@param dst_length_minutes Number of minutes to adjust clock forward
*@retval status of time label w.r.t. dst
*/
static time_is_dst_result
process_local_dst_start_day(const time_duration_type& time_of_day,
unsigned int dst_start_offset_minutes,
long dst_length_minutes)
{
//std::cout << "here" << std::endl;
if (time_of_day < time_duration_type(0,dst_start_offset_minutes,0)) {
return is_not_in_dst;
}
long offset = dst_start_offset_minutes + dst_length_minutes;
if (time_of_day >= time_duration_type(0,offset,0)) {
return is_in_dst;
}
return invalid_time_label;
}
//! Check the local time offset when on the last day of dst
/*! This is the calculation for the DST end day. On that day times
* prior to the conversion time - dst_length (1 am in US) are still
* in dst. Times between the above and the switch time are
* ambiguous. Times after the start_offset are not in dst.
*@param time_of_day Time offset in the day for the local time
*@param dst_end_offset_minutes Local time of day for end of dst
*@retval status of time label w.r.t. dst
*/
static time_is_dst_result
process_local_dst_end_day(const time_duration_type& time_of_day,
unsigned int dst_end_offset_minutes,
long dst_length_minutes)
{
//in US this will be 60 so offset in day is 1,0,0
int offset = dst_end_offset_minutes-dst_length_minutes;
if (time_of_day < time_duration_type(0,offset,0)) {
return is_in_dst;
}
if (time_of_day >= time_duration_type(0,dst_end_offset_minutes,0)) {
return is_not_in_dst;
}
return ambiguous;
}
//! Calculates if the given local time is dst or not
/*! Determines if the time is really in DST or not. Also checks for
* invalid and ambiguous.
* @param current_day The day to check for dst
* @param time_of_day Time offset within the day to check
* @param dst_start_day Starting day of dst for the given locality
* @param dst_start_offset Time offset within day for dst boundary
* @param dst_end_day Ending day of dst for the given locality
* @param dst_end_offset Time offset within day given in dst for dst boundary
* @param dst_length_minutes length of dst adjusment
* @retval The time is either ambiguous, invalid, in dst, or not in dst
*/
static time_is_dst_result
local_is_dst(const date_type& current_day,
const time_duration_type& time_of_day,
const date_type& dst_start_day,
const time_duration_type& dst_start_offset,
const date_type& dst_end_day,
const time_duration_type& dst_end_offset,
const time_duration_type& dst_length)
{
unsigned int start_minutes = static_cast(
dst_start_offset.hours() * 60 + dst_start_offset.minutes());
unsigned int end_minutes = static_cast(
dst_end_offset.hours() * 60 + dst_end_offset.minutes());
long length_minutes = static_cast(
dst_length.hours() * 60 + dst_length.minutes());
return local_is_dst(current_day, time_of_day,
dst_start_day, start_minutes,
dst_end_day, end_minutes,
length_minutes);
}
//! Calculates if the given local time is dst or not
/*! Determines if the time is really in DST or not. Also checks for
* invalid and ambiguous.
* @param current_day The day to check for dst
* @param time_of_day Time offset within the day to check
* @param dst_start_day Starting day of dst for the given locality
* @param dst_start_offset_minutes Offset within day for dst
* boundary (eg 120 for US which is 02:00:00)
* @param dst_end_day Ending day of dst for the given locality
* @param dst_end_offset_minutes Offset within day given in dst for dst
* boundary (eg 120 for US which is 02:00:00)
* @param dst_length_minutes Length of dst adjusment (eg: 60 for US)
* @retval The time is either ambiguous, invalid, in dst, or not in dst
*/
static time_is_dst_result
local_is_dst(const date_type& current_day,
const time_duration_type& time_of_day,
const date_type& dst_start_day,
unsigned int dst_start_offset_minutes,
const date_type& dst_end_day,
unsigned int dst_end_offset_minutes,
long dst_length_minutes)
{
//in northern hemisphere dst is in the middle of the year
if (dst_start_day < dst_end_day) {
if ((current_day > dst_start_day) && (current_day < dst_end_day)) {
return is_in_dst;
}
if ((current_day < dst_start_day) || (current_day > dst_end_day)) {
return is_not_in_dst;
}
}
else {//southern hemisphere dst is at begining /end of year
if ((current_day < dst_start_day) && (current_day > dst_end_day)) {
return is_not_in_dst;
}
if ((current_day > dst_start_day) || (current_day < dst_end_day)) {
return is_in_dst;
}
}
if (current_day == dst_start_day) {
return process_local_dst_start_day(time_of_day,
dst_start_offset_minutes,
dst_length_minutes);
}
if (current_day == dst_end_day) {
return process_local_dst_end_day(time_of_day,
dst_end_offset_minutes,
dst_length_minutes);
}
//you should never reach this statement
return invalid_time_label;
}
};
//! Compile-time configurable daylight savings time calculation engine
/* This template provides the ability to configure a daylight savings
* calculation at compile time covering all the cases. Unfortunately
* because of the number of dimensions related to daylight savings
* calculation the number of parameters is high. In addition, the
* start and end transition rules are complex types that specify
* an algorithm for calculation of the starting day and ending
* day of daylight savings time including the month and day
* specifications (eg: last sunday in October).
*
* @param date_type A type that represents dates, typically gregorian::date
* @param time_duration_type Used for the offset in the day calculations
* @param dst_traits A set of traits that define the rules of dst
* calculation. The dst_trait must include the following:
* start_rule_functor - Rule to calculate the starting date of a
* dst transition (eg: last_kday_of_month).
* start_day - static function that returns month of dst start for
* start_rule_functor
* start_month -static function that returns day or day of week for
* dst start of dst
* end_rule_functor - Rule to calculate the end of dst day.
* end_day - static fucntion that returns end day for end_rule_functor
* end_month - static function that returns end month for end_rule_functor
* dst_start_offset_minutes - number of minutes from start of day to transition to dst -- 120 (or 2:00 am) is typical for the U.S. and E.U.
* dst_start_offset_minutes - number of minutes from start of day to transition off of dst -- 180 (or 3:00 am) is typical for E.U.
* dst_length_minutes - number of minutes that dst shifts clock
*/
template
class dst_calc_engine
{
public:
typedef typename date_type::year_type year_type;
typedef typename date_type::calendar_type calendar_type;
typedef dst_calculator dstcalc;
//! Calculates if the given local time is dst or not
/*! Determines if the time is really in DST or not. Also checks for
* invalid and ambiguous.
* @retval The time is either ambiguous, invalid, in dst, or not in dst
*/
static time_is_dst_result local_is_dst(const date_type& d,
const time_duration_type& td)
{
year_type y = d.year();
date_type dst_start = local_dst_start_day(y);
date_type dst_end = local_dst_end_day(y);
return dstcalc::local_is_dst(d,td,
dst_start,
dst_traits::dst_start_offset_minutes(),
dst_end,
dst_traits::dst_end_offset_minutes(),
dst_traits::dst_shift_length_minutes());
}
static bool is_dst_boundary_day(date_type d)
{
year_type y = d.year();
return ((d == local_dst_start_day(y)) ||
(d == local_dst_end_day(y)));
}
//! The time of day for the dst transition (eg: typically 01:00:00 or 02:00:00)
static time_duration_type dst_offset()
{
return time_duration_type(0,dst_traits::dst_shift_length_minutes(),0);
}
static date_type local_dst_start_day(year_type year)
{
return dst_traits::local_dst_start_day(year);
}
static date_type local_dst_end_day(year_type year)
{
return dst_traits::local_dst_end_day(year);
}
};
//! Depricated: Class to calculate dst boundaries for US time zones
/* Use dst_calc_engine instead.
* In 2007 US/Canada DST rules changed
* (http://en.wikipedia.org/wiki/Energy_Policy_Act_of_2005#Change_to_daylight_saving_time).
*/
template //1 hour == 60 min in US
class us_dst_rules
{
public:
typedef time_duration_type_ time_duration_type;
typedef date_type_ date_type;
typedef typename date_type::year_type year_type;
typedef typename date_type::calendar_type calendar_type;
typedef date_time::last_kday_of_month lkday;
typedef date_time::first_kday_of_month fkday;
typedef date_time::nth_kday_of_month nkday;
typedef dst_calculator dstcalc;
//! Calculates if the given local time is dst or not
/*! Determines if the time is really in DST or not. Also checks for
* invalid and ambiguous.
* @retval The time is either ambiguous, invalid, in dst, or not in dst
*/
static time_is_dst_result local_is_dst(const date_type& d,
const time_duration_type& td)
{
year_type y = d.year();
date_type dst_start = local_dst_start_day(y);
date_type dst_end = local_dst_end_day(y);
return dstcalc::local_is_dst(d,td,
dst_start,dst_start_offset_minutes,
dst_end, dst_start_offset_minutes,
dst_length_minutes);
}
static bool is_dst_boundary_day(date_type d)
{
year_type y = d.year();
return ((d == local_dst_start_day(y)) ||
(d == local_dst_end_day(y)));
}
static date_type local_dst_start_day(year_type year)
{
if (year >= year_type(2007)) {
//second sunday in march
nkday ssim(nkday::second, Sunday, date_time::Mar);
return ssim.get_date(year);
} else {
//first sunday in april
fkday fsia(Sunday, date_time::Apr);
return fsia.get_date(year);
}
}
static date_type local_dst_end_day(year_type year)
{
if (year >= year_type(2007)) {
//first sunday in november
fkday fsin(Sunday, date_time::Nov);
return fsin.get_date(year);
} else {
//last sunday in october
lkday lsio(Sunday, date_time::Oct);
return lsio.get_date(year);
}
}
static time_duration_type dst_offset()
{
return time_duration_type(0,dst_length_minutes,0);
}
private:
};
//! Used for local time adjustments in places that don't use dst
template
class null_dst_rules
{
public:
typedef time_duration_type_ time_duration_type;
typedef date_type_ date_type;
//! Calculates if the given local time is dst or not
/*! @retval Always is_not_in_dst since this is for zones without dst
*/
static time_is_dst_result local_is_dst(const date_type&,
const time_duration_type&)
{
return is_not_in_dst;
}
//! Calculates if the given utc time is in dst
static time_is_dst_result utc_is_dst(const date_type&,
const time_duration_type&)
{
return is_not_in_dst;
}
static bool is_dst_boundary_day(date_type /*d*/)
{
return false;
}
static time_duration_type dst_offset()
{
return time_duration_type(0,0,0);
}
};
} } //namespace date_time
#endif