Chris@16: #ifndef DATE_TIME_DATE_HPP___
Chris@16: #define DATE_TIME_DATE_HPP___
Chris@16: 
Chris@16: /* Copyright (c) 2002,2003 CrystalClear Software, Inc.
Chris@16:  * Use, modification and distribution is subject to the
Chris@16:  * Boost Software License, Version 1.0. (See accompanying
Chris@16:  * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
Chris@16:  * Author: Jeff Garland, Bart Garst
Chris@101:  * $Date$
Chris@16:  */
Chris@16: 
Chris@16: #include <boost/operators.hpp>
Chris@16: #include <boost/date_time/year_month_day.hpp>
Chris@16: #include <boost/date_time/special_defs.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace date_time {
Chris@16: 
Chris@16:   //!Representation of timepoint at the one day level resolution.
Chris@16:   /*!
Chris@16:     The date template represents an interface shell for a date class
Chris@16:     that is based on a year-month-day system such as the gregorian
Chris@16:     or iso systems.  It provides basic operations to enable calculation
Chris@16:     and comparisons.
Chris@16: 
Chris@16:     <b>Theory</b>
Chris@16: 
Chris@16:     This date representation fundamentally departs from the C tm struct
Chris@16:     approach.  The goal for this type is to provide efficient date
Chris@16:     operations (add, subtract) and storage (minimize space to represent)
Chris@16:     in a concrete class.  Thus, the date uses a count internally to
Chris@16:     represent a particular date.  The calendar parameter defines
Chris@16:     the policies for converting the the year-month-day and internal
Chris@16:     counted form here.  Applications that need to perform heavy
Chris@16:     formatting of the same date repeatedly will perform better
Chris@16:     by using the year-month-day representation.
Chris@16: 
Chris@16:     Internally the date uses a day number to represent the date.
Chris@16:     This is a monotonic time representation. This representation
Chris@16:     allows for fast comparison as well as simplifying
Chris@16:     the creation of writing numeric operations.  Essentially, the
Chris@16:     internal day number is like adjusted julian day.  The adjustment
Chris@16:     is determined by the Epoch date which is represented as day 1 of
Chris@16:     the calendar.  Day 0 is reserved for negative infinity so that
Chris@16:     any actual date is automatically greater than negative infinity.
Chris@16:     When a date is constructed from a date or formatted for output,
Chris@16:     the appropriate conversions are applied to create the year, month,
Chris@16:     day representations.
Chris@16:   */
Chris@16: 
Chris@16: 
Chris@16:   template<class T, class calendar, class duration_type_>
Chris@16:   class date : private
Chris@16:        boost::less_than_comparable<T
Chris@16:      , boost::equality_comparable<T
Chris@16:     > >
Chris@16:   {
Chris@16:   public:
Chris@16:     typedef T date_type;
Chris@16:     typedef calendar calendar_type;
Chris@16:     typedef typename calendar::date_traits_type traits_type;
Chris@16:     typedef duration_type_ duration_type;
Chris@16:     typedef typename calendar::year_type year_type;
Chris@16:     typedef typename calendar::month_type month_type;
Chris@16:     typedef typename calendar::day_type day_type;
Chris@16:     typedef typename calendar::ymd_type ymd_type;
Chris@16:     typedef typename calendar::date_rep_type date_rep_type;
Chris@16:     typedef typename calendar::date_int_type date_int_type;
Chris@16:     typedef typename calendar::day_of_week_type day_of_week_type;
Chris@16:     date(year_type y, month_type m, day_type d)
Chris@16:       : days_(calendar::day_number(ymd_type(y, m, d)))
Chris@16:     {}
Chris@16:     date(const ymd_type& ymd)
Chris@16:       : days_(calendar::day_number(ymd))
Chris@16:     {}
Chris@16:     //let the compiler write copy, assignment, and destructor
Chris@16:     year_type        year() const
Chris@16:     {
Chris@16:       ymd_type ymd = calendar::from_day_number(days_);
Chris@16:       return ymd.year;
Chris@16:     }
Chris@16:     month_type       month() const
Chris@16:     {
Chris@16:       ymd_type ymd = calendar::from_day_number(days_);
Chris@16:       return ymd.month;
Chris@16:     }
Chris@16:     day_type         day() const
Chris@16:     {
Chris@16:       ymd_type ymd = calendar::from_day_number(days_);
Chris@16:       return ymd.day;
Chris@16:     }
Chris@16:     day_of_week_type day_of_week() const
Chris@16:     {
Chris@16:       ymd_type ymd = calendar::from_day_number(days_);
Chris@16:       return calendar::day_of_week(ymd);
Chris@16:     }
Chris@16:     ymd_type         year_month_day() const
Chris@16:     {
Chris@16:       return calendar::from_day_number(days_);
Chris@16:     }
Chris@16:     bool operator<(const date_type& rhs)  const
Chris@16:     {
Chris@16:       return days_ < rhs.days_;
Chris@16:     }
Chris@16:     bool operator==(const date_type& rhs) const
Chris@16:     {
Chris@16:       return days_ == rhs.days_;
Chris@16:     }
Chris@16:     //! check to see if date is a special value
Chris@16:     bool is_special()const
Chris@16:     {
Chris@16:       return(is_not_a_date() || is_infinity());
Chris@16:     }
Chris@16:     //! check to see if date is not a value
Chris@16:     bool is_not_a_date()  const
Chris@16:     {
Chris@16:       return traits_type::is_not_a_number(days_);
Chris@16:     }
Chris@16:     //! check to see if date is one of the infinity values
Chris@16:     bool is_infinity()  const
Chris@16:     {
Chris@16:       return traits_type::is_inf(days_);
Chris@16:     }
Chris@16:     //! check to see if date is greater than all possible dates
Chris@16:     bool is_pos_infinity()  const
Chris@16:     {
Chris@16:       return traits_type::is_pos_inf(days_);
Chris@16:     }
Chris@16:     //! check to see if date is greater than all possible dates
Chris@16:     bool is_neg_infinity()  const
Chris@16:     {
Chris@16:       return traits_type::is_neg_inf(days_);
Chris@16:     }
Chris@16:     //! return as a special value or a not_special if a normal date
Chris@16:     special_values as_special()  const
Chris@16:     {
Chris@16:       return traits_type::to_special(days_);
Chris@16:     }
Chris@16:     duration_type operator-(const date_type& d) const
Chris@16:     {
Chris@16:       if (!this->is_special() && !d.is_special())
Chris@16:       {
Chris@16:         // The duration underlying type may be wider than the date underlying type.
Chris@16:         // Thus we calculate the difference in terms of two durations from some common fixed base date.
Chris@16:         typedef typename duration_type::duration_rep_type duration_rep_type;
Chris@16:         return duration_type(static_cast< duration_rep_type >(days_) - static_cast< duration_rep_type >(d.days_));
Chris@16:       }
Chris@16:       else
Chris@16:       {
Chris@16:         // In this case the difference will be a special value, too
Chris@16:         date_rep_type val = date_rep_type(days_) - date_rep_type(d.days_);
Chris@16:         return duration_type(val.as_special());
Chris@16:       }
Chris@16:     }
Chris@16: 
Chris@16:     date_type operator-(const duration_type& dd) const
Chris@16:     {
Chris@16:       if(dd.is_special())
Chris@16:       {
Chris@16:         return date_type(date_rep_type(days_) - dd.get_rep());
Chris@16:       }
Chris@16:       return date_type(date_rep_type(days_) - dd.days());
Chris@16:     }
Chris@16:     date_type operator-=(const duration_type& dd)
Chris@16:     {
Chris@16:       *this = *this - dd;
Chris@16:       return date_type(days_);
Chris@16:     }
Chris@16:     date_rep_type day_count() const
Chris@16:     {
Chris@16:       return days_;
Chris@16:     }
Chris@16:     //allow internal access from operators
Chris@16:     date_type operator+(const duration_type& dd) const
Chris@16:     {
Chris@16:       if(dd.is_special())
Chris@16:       {
Chris@16:         return date_type(date_rep_type(days_) + dd.get_rep());
Chris@16:       }
Chris@16:       return date_type(date_rep_type(days_) + dd.days());
Chris@16:     }
Chris@16:     date_type operator+=(const duration_type& dd)
Chris@16:     {
Chris@16:       *this = *this + dd;
Chris@16:       return date_type(days_);
Chris@16:     }
Chris@16: 
Chris@16:     //see reference
Chris@16:   protected:
Chris@16:     /*! This is a private constructor which allows for the creation of new
Chris@16:       dates.  It is not exposed to users since that would require class
Chris@16:       users to understand the inner workings of the date class.
Chris@16:     */
Chris@16:     explicit date(date_int_type days) : days_(days) {}
Chris@16:     explicit date(date_rep_type days) : days_(days.as_number()) {}
Chris@16:     date_int_type days_;
Chris@16: 
Chris@16:   };
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: } } // namespace date_time
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: #endif