1#ifndef DATE_TIME_PERIOD_HPP___
2#define DATE_TIME_PERIOD_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/*! \file period.hpp
13 This file contain the implementation of the period abstraction. This is
14 basically the same idea as a range. Although this class is intended for
15 use in the time library, it is pretty close to general enough for other
16 numeric uses.
17
18*/
19
20#include <boost/operators.hpp>
21#include <boost/date_time/compiler_config.hpp>
22
23
24namespace boost {
25namespace date_time {
26 //!Provides generalized period type useful in date-time systems
27 /*!This template uses a class to represent a time point within the period
28 and another class to represent a duration. As a result, this class is
29 not appropriate for use when the number and duration representation
30 are the same (eg: in the regular number domain).
31
32 A period can be specified by providing either the begining point and
33 a duration or the begining point and the end point( end is NOT part
34 of the period but 1 unit past it. A period will be "invalid" if either
35 end_point <= begin_point or the given duration is <= 0. Any valid period
36 will return false for is_null().
37
38 Zero length periods are also considered invalid. Zero length periods are
39 periods where the begining and end points are the same, or, the given
40 duration is zero. For a zero length period, the last point will be one
41 unit less than the begining point.
42
43 In the case that the begin and last are the same, the period has a
44 length of one unit.
45
46 The best way to handle periods is usually to provide a begining point and
47 a duration. So, day1 + 7 days is a week period which includes all of the
48 first day and 6 more days (eg: Sun to Sat).
49
50 */
51 template<class point_rep, class duration_rep>
52 class BOOST_SYMBOL_VISIBLE period : private
53 boost::less_than_comparable<period<point_rep, duration_rep>
54 , boost::equality_comparable< period<point_rep, duration_rep>
55 > >
56 {
57 public:
58 typedef point_rep point_type;
59 typedef duration_rep duration_type;
60
61 BOOST_CXX14_CONSTEXPR period(point_rep first_point, point_rep end_point);
62 BOOST_CXX14_CONSTEXPR period(point_rep first_point, duration_rep len);
63 BOOST_CXX14_CONSTEXPR point_rep begin() const;
64 BOOST_CXX14_CONSTEXPR point_rep end() const;
65 BOOST_CXX14_CONSTEXPR point_rep last() const;
66 BOOST_CXX14_CONSTEXPR duration_rep length() const;
67 BOOST_CXX14_CONSTEXPR bool is_null() const;
68 BOOST_CXX14_CONSTEXPR bool operator==(const period& rhs) const;
69 BOOST_CXX14_CONSTEXPR bool operator<(const period& rhs) const;
70 BOOST_CXX14_CONSTEXPR void shift(const duration_rep& d);
71 BOOST_CXX14_CONSTEXPR void expand(const duration_rep& d);
72 BOOST_CXX14_CONSTEXPR bool contains(const point_rep& point) const;
73 BOOST_CXX14_CONSTEXPR bool contains(const period& other) const;
74 BOOST_CXX14_CONSTEXPR bool intersects(const period& other) const;
75 BOOST_CXX14_CONSTEXPR bool is_adjacent(const period& other) const;
76 BOOST_CXX14_CONSTEXPR bool is_before(const point_rep& point) const;
77 BOOST_CXX14_CONSTEXPR bool is_after(const point_rep& point) const;
78 BOOST_CXX14_CONSTEXPR period intersection(const period& other) const;
79 BOOST_CXX14_CONSTEXPR period merge(const period& other) const;
80 BOOST_CXX14_CONSTEXPR period span(const period& other) const;
81 private:
82 point_rep begin_;
83 point_rep last_;
84 };
85
86 //! create a period from begin to last eg: [begin,end)
87 /*! If end <= begin then the period will be invalid
88 */
89 template<class point_rep, class duration_rep>
90 inline BOOST_CXX14_CONSTEXPR
91 period<point_rep,duration_rep>::period(point_rep first_point,
92 point_rep end_point) :
93 begin_(first_point),
94 last_(end_point - duration_rep::unit())
95 {}
96
97 //! create a period as [begin, begin+len)
98 /*! If len is <= 0 then the period will be invalid
99 */
100 template<class point_rep, class duration_rep>
101 inline BOOST_CXX14_CONSTEXPR
102 period<point_rep,duration_rep>::period(point_rep first_point, duration_rep len) :
103 begin_(first_point),
104 last_(first_point + len-duration_rep::unit())
105 { }
106
107
108 //! Return the first element in the period
109 template<class point_rep, class duration_rep>
110 inline BOOST_CXX14_CONSTEXPR
111 point_rep period<point_rep,duration_rep>::begin() const
112 {
113 return begin_;
114 }
115
116 //! Return one past the last element
117 template<class point_rep, class duration_rep>
118 inline BOOST_CXX14_CONSTEXPR
119 point_rep period<point_rep,duration_rep>::end() const
120 {
121 return last_ + duration_rep::unit();
122 }
123
124 //! Return the last item in the period
125 template<class point_rep, class duration_rep>
126 inline BOOST_CXX14_CONSTEXPR
127 point_rep period<point_rep,duration_rep>::last() const
128 {
129 return last_;
130 }
131
132 //! True if period is ill formed (length is zero or less)
133 template<class point_rep, class duration_rep>
134 inline BOOST_CXX14_CONSTEXPR
135 bool period<point_rep,duration_rep>::is_null() const
136 {
137 return end() <= begin_;
138 }
139
140 //! Return the length of the period
141 template<class point_rep, class duration_rep>
142 inline BOOST_CXX14_CONSTEXPR
143 duration_rep period<point_rep,duration_rep>::length() const
144 {
145 if(last_ < begin_){ // invalid period
146 return last_+duration_rep::unit() - begin_;
147 }
148 else{
149 return end() - begin_; // normal case
150 }
151 }
152
153 //! Equality operator
154 template<class point_rep, class duration_rep>
155 inline BOOST_CXX14_CONSTEXPR
156 bool period<point_rep,duration_rep>::operator==(const period& rhs) const
157 {
158 return ((begin_ == rhs.begin_) &&
159 (last_ == rhs.last_));
160 }
161
162 //! Strict as defined by rhs.last <= lhs.last
163 template<class point_rep, class duration_rep>
164 inline BOOST_CXX14_CONSTEXPR
165 bool period<point_rep,duration_rep>::operator<(const period& rhs) const
166 {
167 return (last_ < rhs.begin_);
168 }
169
170
171 //! Shift the start and end by the specified amount
172 template<class point_rep, class duration_rep>
173 inline BOOST_CXX14_CONSTEXPR
174 void period<point_rep,duration_rep>::shift(const duration_rep& d)
175 {
176 begin_ = begin_ + d;
177 last_ = last_ + d;
178 }
179
180 /** Expands the size of the period by the duration on both ends.
181 *
182 *So before expand
183 *@code
184 *
185 * [-------]
186 * ^ ^ ^ ^ ^ ^ ^
187 * 1 2 3 4 5 6 7
188 *
189 *@endcode
190 * After expand(2)
191 *@code
192 *
193 * [----------------------]
194 * ^ ^ ^ ^ ^ ^ ^
195 * 1 2 3 4 5 6 7
196 *
197 *@endcode
198 */
199 template<class point_rep, class duration_rep>
200 inline BOOST_CXX14_CONSTEXPR
201 void period<point_rep,duration_rep>::expand(const duration_rep& d)
202 {
203 begin_ = begin_ - d;
204 last_ = last_ + d;
205 }
206
207 //! True if the point is inside the period, zero length periods contain no points
208 template<class point_rep, class duration_rep>
209 inline BOOST_CXX14_CONSTEXPR
210 bool period<point_rep,duration_rep>::contains(const point_rep& point) const
211 {
212 return ((point >= begin_) &&
213 (point <= last_));
214 }
215
216
217 //! True if this period fully contains (or equals) the other period
218 template<class point_rep, class duration_rep>
219 inline BOOST_CXX14_CONSTEXPR
220 bool period<point_rep,duration_rep>::contains(const period<point_rep,duration_rep>& other) const
221 {
222 return ((begin_ <= other.begin_) && (last_ >= other.last_));
223 }
224
225
226 //! True if periods are next to each other without a gap.
227 /* In the example below, p1 and p2 are adjacent, but p3 is not adjacent
228 * with either of p1 or p2.
229 *@code
230 * [-p1-)
231 * [-p2-)
232 * [-p3-)
233 *@endcode
234 */
235 template<class point_rep, class duration_rep>
236 inline BOOST_CXX14_CONSTEXPR
237 bool period<point_rep,duration_rep>::is_adjacent(const period<point_rep,duration_rep>& other) const
238 {
239 return (other.begin() == end() ||
240 begin_ == other.end());
241 }
242
243
244 //! True if all of the period is prior or t < start
245 /* In the example below only point 1 would evaluate to true.
246 *@code
247 * [---------])
248 * ^ ^ ^ ^ ^
249 * 1 2 3 4 5
250 *
251 *@endcode
252 */
253 template<class point_rep, class duration_rep>
254 inline BOOST_CXX14_CONSTEXPR
255 bool period<point_rep,duration_rep>::is_after(const point_rep& t) const
256 {
257 if (is_null())
258 {
259 return false; //null period isn't after
260 }
261
262 return t < begin_;
263 }
264
265 //! True if all of the period is prior to the passed point or end <= t
266 /* In the example below points 4 and 5 return true.
267 *@code
268 * [---------])
269 * ^ ^ ^ ^ ^
270 * 1 2 3 4 5
271 *
272 *@endcode
273 */
274 template<class point_rep, class duration_rep>
275 inline BOOST_CXX14_CONSTEXPR
276 bool period<point_rep,duration_rep>::is_before(const point_rep& t) const
277 {
278 if (is_null())
279 {
280 return false; //null period isn't before anything
281 }
282
283 return last_ < t;
284 }
285
286
287 //! True if the periods overlap in any way
288 /* In the example below p1 intersects with p2, p4, and p6.
289 *@code
290 * [---p1---)
291 * [---p2---)
292 * [---p3---)
293 * [---p4---)
294 * [-p5-)
295 * [-p6-)
296 *@endcode
297 */
298 template<class point_rep, class duration_rep>
299 inline BOOST_CXX14_CONSTEXPR
300 bool period<point_rep,duration_rep>::intersects(const period<point_rep,duration_rep>& other) const
301 {
302 return ( contains(other.begin_) ||
303 other.contains(begin_) ||
304 ((other.begin_ < begin_) && (other.last_ >= begin_)));
305 }
306
307 //! Returns the period of intersection or invalid range no intersection
308 template<class point_rep, class duration_rep>
309 inline BOOST_CXX14_CONSTEXPR
310 period<point_rep,duration_rep>
311 period<point_rep,duration_rep>::intersection(const period<point_rep,duration_rep>& other) const
312 {
313 if (begin_ > other.begin_) {
314 if (last_ <= other.last_) { //case2
315 return *this;
316 }
317 //case 1
318 return period<point_rep,duration_rep>(begin_, other.end());
319 }
320 else {
321 if (last_ <= other.last_) { //case3
322 return period<point_rep,duration_rep>(other.begin_, this->end());
323 }
324 //case4
325 return other;
326 }
327 //unreachable
328 }
329
330 //! Returns the union of intersecting periods -- or null period
331 /*!
332 */
333 template<class point_rep, class duration_rep>
334 inline BOOST_CXX14_CONSTEXPR
335 period<point_rep,duration_rep>
336 period<point_rep,duration_rep>::merge(const period<point_rep,duration_rep>& other) const
337 {
338 if (this->intersects(other)) {
339 if (begin_ < other.begin_) {
340 return period<point_rep,duration_rep>(begin_, last_ > other.last_ ? this->end() : other.end());
341 }
342
343 return period<point_rep,duration_rep>(other.begin_, last_ > other.last_ ? this->end() : other.end());
344
345 }
346 return period<point_rep,duration_rep>(begin_,begin_); // no intersect return null
347 }
348
349 //! Combine two periods with earliest start and latest end.
350 /*! Combines two periods and any gap between them such that
351 * start = min(p1.start, p2.start)
352 * end = max(p1.end , p2.end)
353 *@code
354 * [---p1---)
355 * [---p2---)
356 * result:
357 * [-----------p3----------)
358 *@endcode
359 */
360 template<class point_rep, class duration_rep>
361 inline BOOST_CXX14_CONSTEXPR
362 period<point_rep,duration_rep>
363 period<point_rep,duration_rep>::span(const period<point_rep,duration_rep>& other) const
364 {
365 point_rep start((begin_ < other.begin_) ? begin() : other.begin());
366 point_rep newend((last_ < other.last_) ? other.end() : this->end());
367 return period<point_rep,duration_rep>(start, newend);
368 }
369
370
371} } //namespace date_time
372
373
374
375#endif
376

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