sl@0: #ifndef DATE_TIME_DATE_HPP___
sl@0: #define DATE_TIME_DATE_HPP___
sl@0: 
sl@0: /* Copyright (c) 2002,2003 CrystalClear Software, Inc.
sl@0:  * Use, modification and distribution is subject to the 
sl@0:  * Boost Software License, Version 1.0. (See accompanying
sl@0:  * file LICENSE-1.0 or http://www.boost.org/LICENSE-1.0)
sl@0:  * Author: Jeff Garland, Bart Garst
sl@0:  * $Date: 2004/01/11 17:41:21 $
sl@0:  */
sl@0: 
sl@0: #include "boost/date_time/year_month_day.hpp"
sl@0: #include "boost/date_time/special_defs.hpp"
sl@0: #include "boost/operators.hpp"
sl@0: 
sl@0: namespace boost {
sl@0: namespace date_time {
sl@0: 
sl@0:   //!Representation of timepoint at the one day level resolution.
sl@0:   /*! 
sl@0:     The date template represents an interface shell for a date class
sl@0:     that is based on a year-month-day system such as the gregorian
sl@0:     or iso systems.  It provides basic operations to enable calculation
sl@0:     and comparisons.  
sl@0: 
sl@0:     <b>Theory</b>
sl@0: 
sl@0:     This date representation fundamentally departs from the C tm struct 
sl@0:     approach.  The goal for this type is to provide efficient date
sl@0:     operations (add, subtract) and storage (minimize space to represent)
sl@0:     in a concrete class.  Thus, the date uses a count internally to
sl@0:     represent a particular date.  The calendar parameter defines 
sl@0:     the policies for converting the the year-month-day and internal
sl@0:     counted form here.  Applications that need to perform heavy
sl@0:     formatting of the same date repeatedly will perform better
sl@0:     by using the year-month-day representation.
sl@0:     
sl@0:     Internally the date uses a day number to represent the date.
sl@0:     This is a monotonic time representation. This representation 
sl@0:     allows for fast comparison as well as simplifying
sl@0:     the creation of writing numeric operations.  Essentially, the 
sl@0:     internal day number is like adjusted julian day.  The adjustment
sl@0:     is determined by the Epoch date which is represented as day 1 of
sl@0:     the calendar.  Day 0 is reserved for negative infinity so that
sl@0:     any actual date is automatically greater than negative infinity.
sl@0:     When a date is constructed from a date or formatted for output,
sl@0:     the appropriate conversions are applied to create the year, month,
sl@0:     day representations.
sl@0:   */
sl@0: 
sl@0:   
sl@0:   template<class T, class calendar, class duration_type_> 
sl@0:   class date : private 
sl@0:        boost::less_than_comparable<T 
sl@0:      , boost::equality_comparable<T 
sl@0:     > >
sl@0:   {
sl@0:   public:
sl@0:     typedef T date_type;
sl@0:     typedef calendar calendar_type;
sl@0:     typedef typename calendar::date_traits_type traits_type;
sl@0:     typedef duration_type_ duration_type;
sl@0:     typedef typename calendar::year_type year_type;
sl@0:     typedef typename calendar::month_type month_type;
sl@0:     typedef typename calendar::day_type day_type;
sl@0:     typedef typename calendar::ymd_type ymd_type;
sl@0:     typedef typename calendar::date_rep_type date_rep_type;
sl@0:     typedef typename calendar::date_int_type date_int_type;
sl@0:     typedef typename calendar::day_of_week_type day_of_week_type;
sl@0:     date(year_type y, month_type m, day_type d) 
sl@0:       : days_(calendar::day_number(ymd_type(y, m, d)))
sl@0:     {}
sl@0:     date(const ymd_type& ymd) 
sl@0:       : days_(calendar::day_number(ymd))
sl@0:       {}
sl@0:     //let the compiler write copy, assignment, and destructor
sl@0:     year_type        year() const
sl@0:     {
sl@0:       ymd_type ymd = calendar::from_day_number(days_); 
sl@0:       return ymd.year;
sl@0:     }
sl@0:     month_type       month() const
sl@0:     {
sl@0:       ymd_type ymd = calendar::from_day_number(days_); 
sl@0:       return ymd.month;
sl@0:     }
sl@0:     day_type         day() const
sl@0:     {
sl@0:       ymd_type ymd = calendar::from_day_number(days_); 
sl@0:       return ymd.day;
sl@0:     }
sl@0:     day_of_week_type day_of_week() const
sl@0:     {
sl@0:       ymd_type ymd = calendar::from_day_number(days_);
sl@0:       return calendar::day_of_week(ymd);
sl@0:     }
sl@0:     ymd_type         year_month_day() const
sl@0:     {
sl@0:       return calendar::from_day_number(days_);
sl@0:     }
sl@0:     bool operator<(const date_type& rhs)  const
sl@0:     {
sl@0:       return days_ < rhs.days_;
sl@0:     }
sl@0:     bool operator==(const date_type& rhs) const
sl@0:     {
sl@0:       return days_ == rhs.days_;
sl@0:     }
sl@0:     //! check to see if date is a special value
sl@0:     bool is_special()const
sl@0:     {
sl@0:       return(is_not_a_date() || is_infinity());
sl@0:     }
sl@0:     //! check to see if date is not a value
sl@0:     bool is_not_a_date()  const
sl@0:     {
sl@0:       return traits_type::is_not_a_number(days_);
sl@0:     }
sl@0:     //! check to see if date is one of the infinity values
sl@0:     bool is_infinity()  const
sl@0:     {
sl@0:       return traits_type::is_inf(days_);
sl@0:     }
sl@0:     //! check to see if date is greater than all possible dates
sl@0:     bool is_pos_infinity()  const
sl@0:     {
sl@0:       return traits_type::is_pos_inf(days_);
sl@0:     }
sl@0:     //! check to see if date is greater than all possible dates
sl@0:     bool is_neg_infinity()  const
sl@0:     {
sl@0:       return traits_type::is_neg_inf(days_);
sl@0:     }
sl@0:     //! return as a special value or a not_special if a normal date
sl@0:     special_values as_special()  const
sl@0:     {
sl@0:       return traits_type::to_special(days_);
sl@0:     }
sl@0:     duration_type operator-(const date_type& d) const
sl@0:     {
sl@0:       date_rep_type val = date_rep_type(days_) - date_rep_type(d.days_);
sl@0:       return duration_type(val.as_number());
sl@0:     }
sl@0:     
sl@0:     date_type operator-(const duration_type& dd) const
sl@0:     {
sl@0:       if(dd.is_special())
sl@0:       {
sl@0:         return date_type(date_rep_type(days_) - dd.get_rep());
sl@0:       }
sl@0:       return date_type(date_rep_type(days_) - dd.days());
sl@0:     }
sl@0:     date_type operator-=(const duration_type& dd)
sl@0:     {
sl@0:       *this = *this - dd;
sl@0:       return date_type(days_);
sl@0:     }
sl@0:     date_rep_type day_count() const 
sl@0:     {
sl@0:       return days_;
sl@0:     };
sl@0:     //allow internal access from operators
sl@0:     date_type operator+(const duration_type& dd) const
sl@0:     {
sl@0:       if(dd.is_special())
sl@0:       {
sl@0:         return date_type(date_rep_type(days_) + dd.get_rep());
sl@0:       }
sl@0:       return date_type(date_rep_type(days_) + dd.days());
sl@0:     }
sl@0:     date_type operator+=(const duration_type& dd)
sl@0:     {
sl@0:       *this = *this + dd; 
sl@0:       return date_type(days_);
sl@0:     }
sl@0: 
sl@0:     //see reference
sl@0:   protected:
sl@0:     /*! This is a private constructor which allows for the creation of new 
sl@0:       dates.  It is not exposed to users since that would require class 
sl@0:       users to understand the inner workings of the date class.
sl@0:     */
sl@0:     explicit date(date_int_type days) : days_(days) {};
sl@0:     explicit date(date_rep_type days) : days_(days.as_number()) {};
sl@0:     date_int_type days_;
sl@0:     
sl@0:   };
sl@0: 
sl@0: 
sl@0: 
sl@0:   
sl@0: } } // namespace date_time
sl@0: 
sl@0: 
sl@0: 
sl@0: 
sl@0: #endif