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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 |