ceph/src/boost/boost/date_time/date.hpp

   1 #ifndef DATE_TIME_DATE_HPP___
   2 #define DATE_TIME_DATE_HPP___
   3
   4 /* Copyright (c) 2002,2003 CrystalClear Software, Inc.
   5  * Use, modification and distribution is subject to the
   6  * Boost Software License, Version 1.0. (See accompanying
   7  * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
   8  * Author: Jeff Garland, Bart Garst
   9  * $Date$
  10  */
  11
  12 #include <boost/operators.hpp>
  13 #include <boost/date_time/compiler_config.hpp>
  14 #include <boost/date_time/year_month_day.hpp>
  15 #include <boost/date_time/special_defs.hpp>
  16
  17 namespace boost {
  18 namespace date_time {
  19
  20   //!Representation of timepoint at the one day level resolution.
  21   /*!
  22     The date template represents an interface shell for a date class
  23     that is based on a year-month-day system such as the gregorian
  24     or iso systems.  It provides basic operations to enable calculation
  25     and comparisons.
  26
  27     <b>Theory</b>
  28
  29     This date representation fundamentally departs from the C tm struct
  30     approach.  The goal for this type is to provide efficient date
  31     operations (add, subtract) and storage (minimize space to represent)
  32     in a concrete class.  Thus, the date uses a count internally to
  33     represent a particular date.  The calendar parameter defines
  34     the policies for converting the the year-month-day and internal
  35     counted form here.  Applications that need to perform heavy
  36     formatting of the same date repeatedly will perform better
  37     by using the year-month-day representation.
  38
  39     Internally the date uses a day number to represent the date.
  40     This is a monotonic time representation. This representation
  41     allows for fast comparison as well as simplifying
  42     the creation of writing numeric operations.  Essentially, the
  43     internal day number is like adjusted julian day.  The adjustment
  44     is determined by the Epoch date which is represented as day 1 of
  45     the calendar.  Day 0 is reserved for negative infinity so that
  46     any actual date is automatically greater than negative infinity.
  47     When a date is constructed from a date or formatted for output,
  48     the appropriate conversions are applied to create the year, month,
  49     day representations.
  50   */
  51
  52
  53   template<class T, class calendar, class duration_type_>
  54   class BOOST_SYMBOL_VISIBLE date : private
  55        boost::less_than_comparable<T
  56      , boost::equality_comparable<T
  57     > >
  58   {
  59   public:
  60     typedef T date_type;
  61     typedef calendar calendar_type;
  62     typedef typename calendar::date_traits_type traits_type;
  63     typedef duration_type_ duration_type;
  64     typedef typename calendar::year_type year_type;
  65     typedef typename calendar::month_type month_type;
  66     typedef typename calendar::day_type day_type;
  67     typedef typename calendar::ymd_type ymd_type;
  68     typedef typename calendar::date_rep_type date_rep_type;
  69     typedef typename calendar::date_int_type date_int_type;
  70     typedef typename calendar::day_of_week_type day_of_week_type;
  71     date(year_type y, month_type m, day_type d)
  72       : days_(calendar::day_number(ymd_type(y, m, d)))
  73     {}
  74     date(const ymd_type& ymd)
  75       : days_(calendar::day_number(ymd))
  76     {}
  77     //let the compiler write copy, assignment, and destructor
  78     year_type        year() const
  79     {
  80       ymd_type ymd = calendar::from_day_number(days_);
  81       return ymd.year;
  82     }
  83     month_type       month() const
  84     {
  85       ymd_type ymd = calendar::from_day_number(days_);
  86       return ymd.month;
  87     }
  88     day_type         day() const
  89     {
  90       ymd_type ymd = calendar::from_day_number(days_);
  91       return ymd.day;
  92     }
  93     day_of_week_type day_of_week() const
  94     {
  95       ymd_type ymd = calendar::from_day_number(days_);
  96       return calendar::day_of_week(ymd);
  97     }
  98     ymd_type         year_month_day() const
  99     {
 100       return calendar::from_day_number(days_);
 101     }
 102     bool operator<(const date_type& rhs)  const
 103     {
 104       return days_ < rhs.days_;
 105     }
 106     bool operator==(const date_type& rhs) const
 107     {
 108       return days_ == rhs.days_;
 109     }
 110     //! check to see if date is a special value
 111     bool is_special()const
 112     {
 113       return(is_not_a_date() || is_infinity());
 114     }
 115     //! check to see if date is not a value
 116     bool is_not_a_date()  const
 117     {
 118       return traits_type::is_not_a_number(days_);
 119     }
 120     //! check to see if date is one of the infinity values
 121     bool is_infinity()  const
 122     {
 123       return traits_type::is_inf(days_);
 124     }
 125     //! check to see if date is greater than all possible dates
 126     bool is_pos_infinity()  const
 127     {
 128       return traits_type::is_pos_inf(days_);
 129     }
 130     //! check to see if date is greater than all possible dates
 131     bool is_neg_infinity()  const
 132     {
 133       return traits_type::is_neg_inf(days_);
 134     }
 135     //! return as a special value or a not_special if a normal date
 136     special_values as_special()  const
 137     {
 138       return traits_type::to_special(days_);
 139     }
 140     duration_type operator-(const date_type& d) const
 141     {
 142       if (!this->is_special() && !d.is_special())
 143       {
 144         // The duration underlying type may be wider than the date underlying type.
 145         // Thus we calculate the difference in terms of two durations from some common fixed base date.
 146         typedef typename duration_type::duration_rep_type duration_rep_type;
 147         return duration_type(static_cast< duration_rep_type >(days_) - static_cast< duration_rep_type >(d.days_));
 148       }
 149       else
 150       {
 151         // In this case the difference will be a special value, too
 152         date_rep_type val = date_rep_type(days_) - date_rep_type(d.days_);
 153         return duration_type(val.as_special());
 154       }
 155     }
 156
 157     date_type operator-(const duration_type& dd) const
 158     {
 159       if(dd.is_special())
 160       {
 161         return date_type(date_rep_type(days_) - dd.get_rep());
 162       }
 163       return date_type(date_rep_type(days_) - static_cast<date_int_type>(dd.days()));
 164     }
 165     date_type operator-=(const duration_type& dd)
 166     {
 167       *this = *this - dd;
 168       return date_type(days_);
 169     }
 170     date_rep_type day_count() const
 171     {
 172       return days_;
 173     }
 174     //allow internal access from operators
 175     date_type operator+(const duration_type& dd) const
 176     {
 177       if(dd.is_special())
 178       {
 179         return date_type(date_rep_type(days_) + dd.get_rep());
 180       }
 181       return date_type(date_rep_type(days_) + static_cast<date_int_type>(dd.days()));
 182     }
 183     date_type operator+=(const duration_type& dd)
 184     {
 185       *this = *this + dd;
 186       return date_type(days_);
 187     }
 188
 189     //see reference
 190   protected:
 191     /*! This is a private constructor which allows for the creation of new
 192       dates.  It is not exposed to users since that would require class
 193       users to understand the inner workings of the date class.
 194     */
 195     explicit date(date_int_type days) : days_(days) {}
 196     explicit date(date_rep_type days) : days_(days.as_number()) {}
 197     date_int_type days_;
 198
 199   };
 200
 201
 202
 203
 204 } } // namespace date_time
 205
 206
 207
 208
 209 #endif