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