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