1#ifndef DATE_TIME_DATE_GENERATORS_HPP__
2#define DATE_TIME_DATE_GENERATORS_HPP__
3
4/* Copyright (c) 2002,2003,2005 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/*! @file date_generators.hpp
13 Definition and implementation of date algorithm templates
14*/
15
16#include <sstream>
17#include <stdexcept>
18#include <boost/throw_exception.hpp>
19#include <boost/date_time/date.hpp>
20#include <boost/date_time/compiler_config.hpp>
21
22namespace boost {
23namespace date_time {
24
25 //! Base class for all generators that take a year and produce a date.
26 /*! This class is a base class for polymorphic function objects that take
27 a year and produce a concrete date.
28 @tparam date_type The type representing a date. This type must
29 export a calender_type which defines a year_type.
30 */
31 template<class date_type>
32 class year_based_generator
33 {
34 public:
35 typedef typename date_type::calendar_type calendar_type;
36 typedef typename calendar_type::year_type year_type;
37 year_based_generator() {}
38 virtual ~year_based_generator() {}
39 virtual date_type get_date(year_type y) const = 0;
40 //! Returns a string for use in a POSIX time_zone string
41 virtual std::string to_string() const = 0;
42 };
43
44 //! Generates a date by applying the year to the given month and day.
45 /*!
46 Example usage:
47 @code
48 partial_date pd(1, Jan);
49 partial_date pd2(70);
50 date d = pd.get_date(2002); //2002-Jan-01
51 date d2 = pd2.get_date(2002); //2002-Mar-10
52 @endcode
53 \ingroup date_alg
54 */
55 template<class date_type>
56 class partial_date : public year_based_generator<date_type>
57 {
58 public:
59 typedef typename date_type::calendar_type calendar_type;
60 typedef typename calendar_type::day_type day_type;
61 typedef typename calendar_type::month_type month_type;
62 typedef typename calendar_type::year_type year_type;
63 typedef typename date_type::duration_type duration_type;
64 typedef typename duration_type::duration_rep duration_rep;
65 partial_date(day_type d, month_type m) :
66 day_(d),
67 month_(m)
68 {}
69 //! Partial date created from number of days into year. Range 1-366
70 /*! Allowable values range from 1 to 366. 1=Jan1, 366=Dec31. If argument
71 * exceeds range, partial_date will be created with closest in-range value.
72 * 60 will always be Feb29, if get_date() is called with a non-leap year
73 * an exception will be thrown */
74 partial_date(duration_rep days) :
75 day_(1), // default values
76 month_(1)
77 {
78 date_type d1(2000,1,1);
79 if(days > 1) {
80 if(days > 366) // prevents wrapping
81 {
82 days = 366;
83 }
84 days = days - 1;
85 duration_type dd(days);
86 d1 = d1 + dd;
87 }
88 day_ = d1.day();
89 month_ = d1.month();
90 }
91 //! Return a concrete date when provided with a year specific year.
92 /*! Will throw an 'invalid_argument' exception if a partial_date object,
93 * instantiated with Feb-29, has get_date called with a non-leap year.
94 * Example:
95 * @code
96 * partial_date pd(29, Feb);
97 * pd.get_date(2003); // throws invalid_argument exception
98 * pg.get_date(2000); // returns 2000-2-29
99 * @endcode
100 */
101 date_type get_date(year_type y) const BOOST_OVERRIDE
102 {
103 if((day_ == 29) && (month_ == 2) && !(calendar_type::is_leap_year(y))) {
104 std::ostringstream ss;
105 ss << "No Feb 29th in given year of " << y << ".";
106 boost::throw_exception(e: std::invalid_argument(ss.str()));
107 }
108 return date_type(y, month_, day_);
109 }
110 date_type operator()(year_type y) const
111 {
112 return get_date(y);
113 //return date_type(y, month_, day_);
114 }
115 bool operator==(const partial_date& rhs) const
116 {
117 return (month_ == rhs.month_) && (day_ == rhs.day_);
118 }
119 bool operator<(const partial_date& rhs) const
120 {
121 if (month_ < rhs.month_) return true;
122 if (month_ > rhs.month_) return false;
123 //months are equal
124 return (day_ < rhs.day_);
125 }
126
127 // added for streaming purposes
128 month_type month() const
129 {
130 return month_;
131 }
132 day_type day() const
133 {
134 return day_;
135 }
136
137 //! Returns string suitable for use in POSIX time zone string
138 /*! Returns string formatted with up to 3 digits:
139 * Jan-01 == "0"
140 * Feb-29 == "58"
141 * Dec-31 == "365" */
142 std::string to_string() const BOOST_OVERRIDE
143 {
144 std::ostringstream ss;
145 date_type d(2004, month_, day_);
146 unsigned short c = d.day_of_year();
147 c--; // numbered 0-365 while day_of_year is 1 based...
148 ss << c;
149 return ss.str();
150 }
151 private:
152 day_type day_;
153 month_type month_;
154 };
155
156 //! Returns nth arg as string. 1 -> "first", 2 -> "second", max is 5.
157 inline const char* nth_as_str(int ele)
158 {
159 static const char* const _nth_as_str[] = {"out of range", "first", "second",
160 "third", "fourth", "fifth"};
161 if(ele >= 1 && ele <= 5) {
162 return _nth_as_str[ele];
163 }
164 else {
165 return _nth_as_str[0];
166 }
167 }
168
169 //! Useful generator functor for finding holidays
170 /*! Based on the idea in Cal. Calc. for finding holidays that are
171 * the 'first Monday of September'. When instantiated with
172 * 'fifth' kday of month, the result will be the last kday of month
173 * which can be the fourth or fifth depending on the structure of
174 * the month.
175 *
176 * The algorithm here basically guesses for the first
177 * day of the month. Then finds the first day of the correct
178 * type. That is, if the first of the month is a Tuesday
179 * and it needs Wednesday then we simply increment by a day
180 * and then we can add the length of a week until we get
181 * to the 'nth kday'. There are probably more efficient
182 * algorithms based on using a mod 7, but this one works
183 * reasonably well for basic applications.
184 * \ingroup date_alg
185 */
186 template<class date_type>
187 class nth_kday_of_month : public year_based_generator<date_type>
188 {
189 public:
190 typedef typename date_type::calendar_type calendar_type;
191 typedef typename calendar_type::day_of_week_type day_of_week_type;
192 typedef typename calendar_type::month_type month_type;
193 typedef typename calendar_type::year_type year_type;
194 typedef typename date_type::duration_type duration_type;
195 enum week_num {first=1, second, third, fourth, fifth};
196 nth_kday_of_month(week_num week_no,
197 day_of_week_type dow,
198 month_type m) :
199 month_(m),
200 wn_(week_no),
201 dow_(dow)
202 {}
203 //! Return a concrete date when provided with a year specific year.
204 date_type get_date(year_type y) const BOOST_OVERRIDE
205 {
206 date_type d(y, month_, 1); //first day of month
207 duration_type one_day(1);
208 duration_type one_week(7);
209 while (dow_ != d.day_of_week()) {
210 d = d + one_day;
211 }
212 int week = 1;
213 while (week < wn_) {
214 d = d + one_week;
215 week++;
216 }
217 // remove wrapping to next month behavior
218 if(d.month() != month_) {
219 d = d - one_week;
220 }
221 return d;
222 }
223 // added for streaming
224 month_type month() const
225 {
226 return month_;
227 }
228 week_num nth_week() const
229 {
230 return wn_;
231 }
232 day_of_week_type day_of_week() const
233 {
234 return dow_;
235 }
236 const char* nth_week_as_str() const
237 {
238 return nth_as_str(wn_);
239 }
240 //! Returns string suitable for use in POSIX time zone string
241 /*! Returns a string formatted as "M4.3.0" ==> 3rd Sunday in April. */
242 std::string to_string() const BOOST_OVERRIDE
243 {
244 std::ostringstream ss;
245 ss << 'M'
246 << static_cast<int>(month_) << '.'
247 << static_cast<int>(wn_) << '.'
248 << static_cast<int>(dow_);
249 return ss.str();
250 }
251 private:
252 month_type month_;
253 week_num wn_;
254 day_of_week_type dow_;
255 };
256
257 //! Useful generator functor for finding holidays and daylight savings
258 /*! Similar to nth_kday_of_month, but requires less paramters
259 * \ingroup date_alg
260 */
261 template<class date_type>
262 class first_kday_of_month : public year_based_generator<date_type>
263 {
264 public:
265 typedef typename date_type::calendar_type calendar_type;
266 typedef typename calendar_type::day_of_week_type day_of_week_type;
267 typedef typename calendar_type::month_type month_type;
268 typedef typename calendar_type::year_type year_type;
269 typedef typename date_type::duration_type duration_type;
270 //!Specify the first 'Sunday' in 'April' spec
271 /*!@param dow The day of week, eg: Sunday, Monday, etc
272 * @param m The month of the year, eg: Jan, Feb, Mar, etc
273 */
274 first_kday_of_month(day_of_week_type dow, month_type m) :
275 month_(m),
276 dow_(dow)
277 {}
278 //! Return a concrete date when provided with a year specific year.
279 date_type get_date(year_type year) const BOOST_OVERRIDE
280 {
281 date_type d(year, month_,1);
282 duration_type one_day(1);
283 while (dow_ != d.day_of_week()) {
284 d = d + one_day;
285 }
286 return d;
287 }
288 // added for streaming
289 month_type month() const
290 {
291 return month_;
292 }
293 day_of_week_type day_of_week() const
294 {
295 return dow_;
296 }
297 //! Returns string suitable for use in POSIX time zone string
298 /*! Returns a string formatted as "M4.1.0" ==> 1st Sunday in April. */
299 std::string to_string() const BOOST_OVERRIDE
300 {
301 std::ostringstream ss;
302 ss << 'M'
303 << static_cast<int>(month_) << '.'
304 << 1 << '.'
305 << static_cast<int>(dow_);
306 return ss.str();
307 }
308 private:
309 month_type month_;
310 day_of_week_type dow_;
311 };
312
313
314
315 //! Calculate something like Last Sunday of January
316 /*! Useful generator functor for finding holidays and daylight savings
317 * Get the last day of the month and then calculate the difference
318 * to the last previous day.
319 * @tparam date_type A date class that exports day_of_week, month_type, etc.
320 * \ingroup date_alg
321 */
322 template<class date_type>
323 class last_kday_of_month : public year_based_generator<date_type>
324 {
325 public:
326 typedef typename date_type::calendar_type calendar_type;
327 typedef typename calendar_type::day_of_week_type day_of_week_type;
328 typedef typename calendar_type::month_type month_type;
329 typedef typename calendar_type::year_type year_type;
330 typedef typename date_type::duration_type duration_type;
331 //!Specify the date spec like last 'Sunday' in 'April' spec
332 /*!@param dow The day of week, eg: Sunday, Monday, etc
333 * @param m The month of the year, eg: Jan, Feb, Mar, etc
334 */
335 last_kday_of_month(day_of_week_type dow, month_type m) :
336 month_(m),
337 dow_(dow)
338 {}
339 //! Return a concrete date when provided with a year specific year.
340 date_type get_date(year_type year) const BOOST_OVERRIDE
341 {
342 date_type d(year, month_, calendar_type::end_of_month_day(year,month_));
343 duration_type one_day(1);
344 while (dow_ != d.day_of_week()) {
345 d = d - one_day;
346 }
347 return d;
348 }
349 // added for streaming
350 month_type month() const
351 {
352 return month_;
353 }
354 day_of_week_type day_of_week() const
355 {
356 return dow_;
357 }
358 //! Returns string suitable for use in POSIX time zone string
359 /*! Returns a string formatted as "M4.5.0" ==> last Sunday in April. */
360 std::string to_string() const BOOST_OVERRIDE
361 {
362 std::ostringstream ss;
363 ss << 'M'
364 << static_cast<int>(month_) << '.'
365 << 5 << '.'
366 << static_cast<int>(dow_);
367 return ss.str();
368 }
369 private:
370 month_type month_;
371 day_of_week_type dow_;
372 };
373
374
375 //! Calculate something like "First Sunday after Jan 1,2002
376 /*! Date generator that takes a date and finds kday after
377 *@code
378 typedef boost::date_time::first_kday_after<date> firstkdayafter;
379 firstkdayafter fkaf(Monday);
380 fkaf.get_date(date(2002,Feb,1));
381 @endcode
382 * \ingroup date_alg
383 */
384 template<class date_type>
385 class first_kday_after
386 {
387 public:
388 typedef typename date_type::calendar_type calendar_type;
389 typedef typename calendar_type::day_of_week_type day_of_week_type;
390 typedef typename date_type::duration_type duration_type;
391 first_kday_after(day_of_week_type dow) :
392 dow_(dow)
393 {}
394 //! Return next kday given.
395 date_type get_date(date_type start_day) const
396 {
397 duration_type one_day(1);
398 date_type d = start_day + one_day;
399 while (dow_ != d.day_of_week()) {
400 d = d + one_day;
401 }
402 return d;
403 }
404 // added for streaming
405 day_of_week_type day_of_week() const
406 {
407 return dow_;
408 }
409 private:
410 day_of_week_type dow_;
411 };
412
413 //! Calculate something like "First Sunday before Jan 1,2002
414 /*! Date generator that takes a date and finds kday after
415 *@code
416 typedef boost::date_time::first_kday_before<date> firstkdaybefore;
417 firstkdaybefore fkbf(Monday);
418 fkbf.get_date(date(2002,Feb,1));
419 @endcode
420 * \ingroup date_alg
421 */
422 template<class date_type>
423 class first_kday_before
424 {
425 public:
426 typedef typename date_type::calendar_type calendar_type;
427 typedef typename calendar_type::day_of_week_type day_of_week_type;
428 typedef typename date_type::duration_type duration_type;
429 first_kday_before(day_of_week_type dow) :
430 dow_(dow)
431 {}
432 //! Return next kday given.
433 date_type get_date(date_type start_day) const
434 {
435 duration_type one_day(1);
436 date_type d = start_day - one_day;
437 while (dow_ != d.day_of_week()) {
438 d = d - one_day;
439 }
440 return d;
441 }
442 // added for streaming
443 day_of_week_type day_of_week() const
444 {
445 return dow_;
446 }
447 private:
448 day_of_week_type dow_;
449 };
450
451 //! Calculates the number of days until the next weekday
452 /*! Calculates the number of days until the next weekday.
453 * If the date given falls on a Sunday and the given weekday
454 * is Tuesday the result will be 2 days */
455 template<typename date_type, class weekday_type>
456 inline
457 typename date_type::duration_type days_until_weekday(const date_type& d, const weekday_type& wd)
458 {
459 typedef typename date_type::duration_type duration_type;
460 duration_type wks(0);
461 duration_type dd(wd.as_number() - d.day_of_week().as_number());
462 if(dd.is_negative()){
463 wks = duration_type(7);
464 }
465 return dd + wks;
466 }
467
468 //! Calculates the number of days since the previous weekday
469 /*! Calculates the number of days since the previous weekday
470 * If the date given falls on a Sunday and the given weekday
471 * is Tuesday the result will be 5 days. The answer will be a positive
472 * number because Tuesday is 5 days before Sunday, not -5 days before. */
473 template<typename date_type, class weekday_type>
474 inline
475 typename date_type::duration_type days_before_weekday(const date_type& d, const weekday_type& wd)
476 {
477 typedef typename date_type::duration_type duration_type;
478 duration_type wks(0);
479 duration_type dd(wd.as_number() - d.day_of_week().as_number());
480 if(dd.days() > 0){
481 wks = duration_type(7);
482 }
483 // we want a number of days, not an offset. The value returned must
484 // be zero or larger.
485 return (-dd + wks);
486 }
487
488 //! Generates a date object representing the date of the following weekday from the given date
489 /*! Generates a date object representing the date of the following
490 * weekday from the given date. If the date given is 2004-May-9
491 * (a Sunday) and the given weekday is Tuesday then the resulting date
492 * will be 2004-May-11. */
493 template<class date_type, class weekday_type>
494 inline
495 date_type next_weekday(const date_type& d, const weekday_type& wd)
496 {
497 return d + days_until_weekday(d, wd);
498 }
499
500 //! Generates a date object representing the date of the previous weekday from the given date
501 /*! Generates a date object representing the date of the previous
502 * weekday from the given date. If the date given is 2004-May-9
503 * (a Sunday) and the given weekday is Tuesday then the resulting date
504 * will be 2004-May-4. */
505 template<class date_type, class weekday_type>
506 inline
507 date_type previous_weekday(const date_type& d, const weekday_type& wd)
508 {
509 return d - days_before_weekday(d, wd);
510 }
511
512} } //namespace date_time
513
514#endif
515

source code of include/boost/date_time/date_generators.hpp