boost/date_time/date_generators.hpp
#ifndef DATE_TIME_DATE_GENERATORS_HPP__ #define DATE_TIME_DATE_GENERATORS_HPP__ /* Copyright (c) 2002,2003,2005 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 date_generators.hpp Definition and implementation of date algorithm templates */ #include <stdexcept> #include <sstream> #include <boost/throw_exception.hpp> #include <boost/date_time/date.hpp> #include <boost/date_time/compiler_config.hpp> namespace boost { namespace date_time { //! Base class for all generators that take a year and produce a date. /*! This class is a base class for polymorphic function objects that take a year and produce a concrete date. @tparam date_type The type representing a date. This type must export a calender_type which defines a year_type. */ template<class date_type> class year_based_generator { public: typedef typename date_type::calendar_type calendar_type; typedef typename calendar_type::year_type year_type; year_based_generator() {} virtual ~year_based_generator() {} virtual date_type get_date(year_type y) const = 0; //! Returns a string for use in a POSIX time_zone string virtual std::string to_string() const =0; }; //! Generates a date by applying the year to the given month and day. /*! Example usage: @code partial_date pd(1, Jan); partial_date pd2(70); date d = pd.get_date(2002); //2002-Jan-01 date d2 = pd2.get_date(2002); //2002-Mar-10 @endcode \ingroup date_alg */ template<class date_type> class partial_date : public year_based_generator<date_type> { public: typedef typename date_type::calendar_type calendar_type; typedef typename calendar_type::day_type day_type; typedef typename calendar_type::month_type month_type; typedef typename calendar_type::year_type year_type; typedef typename date_type::duration_type duration_type; typedef typename duration_type::duration_rep duration_rep; partial_date(day_type d, month_type m) : day_(d), month_(m) {} //! Partial date created from number of days into year. Range 1-366 /*! Allowable values range from 1 to 366. 1=Jan1, 366=Dec31. If argument * exceeds range, partial_date will be created with closest in-range value. * 60 will always be Feb29, if get_date() is called with a non-leap year * an exception will be thrown */ partial_date(duration_rep days) : day_(1), // default values month_(1) { date_type d1(2000,1,1); if(days > 1) { if(days > 366) // prevents wrapping { days = 366; } days = days - 1; duration_type dd(days); d1 = d1 + dd; } day_ = d1.day(); month_ = d1.month(); } //! Return a concrete date when provided with a year specific year. /*! Will throw an 'invalid_argument' exception if a partial_date object, * instantiated with Feb-29, has get_date called with a non-leap year. * Example: * @code * partial_date pd(29, Feb); * pd.get_date(2003); // throws invalid_argument exception * pg.get_date(2000); // returns 2000-2-29 * @endcode */ date_type get_date(year_type y) const { if((day_ == 29) && (month_ == 2) && !(calendar_type::is_leap_year(y))) { std::ostringstream ss; ss << "No Feb 29th in given year of " << y << "."; boost::throw_exception(std::invalid_argument(ss.str())); } return date_type(y, month_, day_); } date_type operator()(year_type y) const { return get_date(y); //return date_type(y, month_, day_); } bool operator==(const partial_date& rhs) const { return (month_ == rhs.month_) && (day_ == rhs.day_); } bool operator<(const partial_date& rhs) const { if (month_ < rhs.month_) return true; if (month_ > rhs.month_) return false; //months are equal return (day_ < rhs.day_); } // added for streaming purposes month_type month() const { return month_; } day_type day() const { return day_; } //! Returns string suitable for use in POSIX time zone string /*! Returns string formatted with up to 3 digits: * Jan-01 == "0" * Feb-29 == "58" * Dec-31 == "365" */ virtual std::string to_string() const { std::ostringstream ss; date_type d(2004, month_, day_); unsigned short c = d.day_of_year(); c--; // numbered 0-365 while day_of_year is 1 based... ss << c; return ss.str(); } private: day_type day_; month_type month_; }; //! Returns nth arg as string. 1 -> "first", 2 -> "second", max is 5. BOOST_DATE_TIME_DECL const char* nth_as_str(int n); //! Useful generator functor for finding holidays /*! Based on the idea in Cal. Calc. for finding holidays that are * the 'first Monday of September'. When instantiated with * 'fifth' kday of month, the result will be the last kday of month * which can be the fourth or fifth depending on the structure of * the month. * * The algorithm here basically guesses for the first * day of the month. Then finds the first day of the correct * type. That is, if the first of the month is a Tuesday * and it needs Wenesday then we simply increment by a day * and then we can add the length of a week until we get * to the 'nth kday'. There are probably more efficient * algorithms based on using a mod 7, but this one works * reasonably well for basic applications. * \ingroup date_alg */ template<class date_type> class nth_kday_of_month : public year_based_generator<date_type> { public: typedef typename date_type::calendar_type calendar_type; typedef typename calendar_type::day_of_week_type day_of_week_type; typedef typename calendar_type::month_type month_type; typedef typename calendar_type::year_type year_type; typedef typename date_type::duration_type duration_type; enum week_num {first=1, second, third, fourth, fifth}; nth_kday_of_month(week_num week_no, day_of_week_type dow, month_type m) : month_(m), wn_(week_no), dow_(dow) {} //! Return a concrete date when provided with a year specific year. date_type get_date(year_type y) const { date_type d(y, month_, 1); //first day of month duration_type one_day(1); duration_type one_week(7); while (dow_ != d.day_of_week()) { d = d + one_day; } int week = 1; while (week < wn_) { d = d + one_week; week++; } // remove wrapping to next month behavior if(d.month() != month_) { d = d - one_week; } return d; } // added for streaming month_type month() const { return month_; } week_num nth_week() const { return wn_; } day_of_week_type day_of_week() const { return dow_; } const char* nth_week_as_str() const { return nth_as_str(wn_); } //! Returns string suitable for use in POSIX time zone string /*! Returns a string formatted as "M4.3.0" ==> 3rd Sunday in April. */ virtual std::string to_string() const { std::ostringstream ss; ss << 'M' << static_cast<int>(month_) << '.' << static_cast<int>(wn_) << '.' << static_cast<int>(dow_); return ss.str(); } private: month_type month_; week_num wn_; day_of_week_type dow_; }; //! Useful generator functor for finding holidays and daylight savings /*! Similar to nth_kday_of_month, but requires less paramters * \ingroup date_alg */ template<class date_type> class first_kday_of_month : public year_based_generator<date_type> { public: typedef typename date_type::calendar_type calendar_type; typedef typename calendar_type::day_of_week_type day_of_week_type; typedef typename calendar_type::month_type month_type; typedef typename calendar_type::year_type year_type; typedef typename date_type::duration_type duration_type; //!Specify the first 'Sunday' in 'April' spec /*!@param dow The day of week, eg: Sunday, Monday, etc * @param m The month of the year, eg: Jan, Feb, Mar, etc */ first_kday_of_month(day_of_week_type dow, month_type m) : month_(m), dow_(dow) {} //! Return a concrete date when provided with a year specific year. date_type get_date(year_type year) const { date_type d(year, month_,1); duration_type one_day(1); while (dow_ != d.day_of_week()) { d = d + one_day; } return d; } // added for streaming month_type month() const { return month_; } day_of_week_type day_of_week() const { return dow_; } //! Returns string suitable for use in POSIX time zone string /*! Returns a string formatted as "M4.1.0" ==> 1st Sunday in April. */ virtual std::string to_string() const { std::ostringstream ss; ss << 'M' << static_cast<int>(month_) << '.' << 1 << '.' << static_cast<int>(dow_); return ss.str(); } private: month_type month_; day_of_week_type dow_; }; //! Calculate something like Last Sunday of January /*! Useful generator functor for finding holidays and daylight savings * Get the last day of the month and then calculate the difference * to the last previous day. * @tparam date_type A date class that exports day_of_week, month_type, etc. * \ingroup date_alg */ template<class date_type> class last_kday_of_month : public year_based_generator<date_type> { public: typedef typename date_type::calendar_type calendar_type; typedef typename calendar_type::day_of_week_type day_of_week_type; typedef typename calendar_type::month_type month_type; typedef typename calendar_type::year_type year_type; typedef typename date_type::duration_type duration_type; //!Specify the date spec like last 'Sunday' in 'April' spec /*!@param dow The day of week, eg: Sunday, Monday, etc * @param m The month of the year, eg: Jan, Feb, Mar, etc */ last_kday_of_month(day_of_week_type dow, month_type m) : month_(m), dow_(dow) {} //! Return a concrete date when provided with a year specific year. date_type get_date(year_type year) const { date_type d(year, month_, calendar_type::end_of_month_day(year,month_)); duration_type one_day(1); while (dow_ != d.day_of_week()) { d = d - one_day; } return d; } // added for streaming month_type month() const { return month_; } day_of_week_type day_of_week() const { return dow_; } //! Returns string suitable for use in POSIX time zone string /*! Returns a string formatted as "M4.5.0" ==> last Sunday in April. */ virtual std::string to_string() const { std::ostringstream ss; ss << 'M' << static_cast<int>(month_) << '.' << 5 << '.' << static_cast<int>(dow_); return ss.str(); } private: month_type month_; day_of_week_type dow_; }; //! Calculate something like "First Sunday after Jan 1,2002 /*! Date generator that takes a date and finds kday after *@code typedef boost::date_time::first_kday_after<date> firstkdayafter; firstkdayafter fkaf(Monday); fkaf.get_date(date(2002,Feb,1)); @endcode * \ingroup date_alg */ template<class date_type> class first_kday_after { public: typedef typename date_type::calendar_type calendar_type; typedef typename calendar_type::day_of_week_type day_of_week_type; typedef typename date_type::duration_type duration_type; first_kday_after(day_of_week_type dow) : dow_(dow) {} //! Return next kday given. date_type get_date(date_type start_day) const { duration_type one_day(1); date_type d = start_day + one_day; while (dow_ != d.day_of_week()) { d = d + one_day; } return d; } // added for streaming day_of_week_type day_of_week() const { return dow_; } private: day_of_week_type dow_; }; //! Calculate something like "First Sunday before Jan 1,2002 /*! Date generator that takes a date and finds kday after *@code typedef boost::date_time::first_kday_before<date> firstkdaybefore; firstkdaybefore fkbf(Monday); fkbf.get_date(date(2002,Feb,1)); @endcode * \ingroup date_alg */ template<class date_type> class first_kday_before { public: typedef typename date_type::calendar_type calendar_type; typedef typename calendar_type::day_of_week_type day_of_week_type; typedef typename date_type::duration_type duration_type; first_kday_before(day_of_week_type dow) : dow_(dow) {} //! Return next kday given. date_type get_date(date_type start_day) const { duration_type one_day(1); date_type d = start_day - one_day; while (dow_ != d.day_of_week()) { d = d - one_day; } return d; } // added for streaming day_of_week_type day_of_week() const { return dow_; } private: day_of_week_type dow_; }; //! Calculates the number of days until the next weekday /*! Calculates the number of days until the next weekday. * If the date given falls on a Sunday and the given weekday * is Tuesday the result will be 2 days */ template<typename date_type, class weekday_type> inline typename date_type::duration_type days_until_weekday(const date_type& d, const weekday_type& wd) { typedef typename date_type::duration_type duration_type; duration_type wks(0); duration_type dd(wd.as_number() - d.day_of_week().as_number()); if(dd.is_negative()){ wks = duration_type(7); } return dd + wks; } //! Calculates the number of days since the previous weekday /*! Calculates the number of days since the previous weekday * If the date given falls on a Sunday and the given weekday * is Tuesday the result will be 5 days. The answer will be a positive * number because Tuesday is 5 days before Sunday, not -5 days before. */ template<typename date_type, class weekday_type> inline typename date_type::duration_type days_before_weekday(const date_type& d, const weekday_type& wd) { typedef typename date_type::duration_type duration_type; duration_type wks(0); duration_type dd(wd.as_number() - d.day_of_week().as_number()); if(dd.days() > 0){ wks = duration_type(7); } // we want a number of days, not an offset. The value returned must // be zero or larger. return (-dd + wks); } //! Generates a date object representing the date of the following weekday from the given date /*! Generates a date object representing the date of the following * weekday from the given date. If the date given is 2004-May-9 * (a Sunday) and the given weekday is Tuesday then the resulting date * will be 2004-May-11. */ template<class date_type, class weekday_type> inline date_type next_weekday(const date_type& d, const weekday_type& wd) { return d + days_until_weekday(d, wd); } //! Generates a date object representing the date of the previous weekday from the given date /*! Generates a date object representing the date of the previous * weekday from the given date. If the date given is 2004-May-9 * (a Sunday) and the given weekday is Tuesday then the resulting date * will be 2004-May-4. */ template<class date_type, class weekday_type> inline date_type previous_weekday(const date_type& d, const weekday_type& wd) { return d - days_before_weekday(d, wd); } } } //namespace date_time #endif