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 | |
22 | |
23 | namespace boost { |
24 | namespace date_time { |
25 | //!Provides generalized period type useful in date-time systems |
26 | /*!This template uses a class to represent a time point within the period |
27 | and another class to represent a duration. As a result, this class is |
28 | not appropriate for use when the number and duration representation |
29 | are the same (eg: in the regular number domain). |
30 | |
31 | A period can be specified by providing either the begining point and |
32 | a duration or the begining point and the end point( end is NOT part |
33 | of the period but 1 unit past it. A period will be "invalid" if either |
34 | end_point <= begin_point or the given duration is <= 0. Any valid period |
35 | will return false for is_null(). |
36 | |
37 | Zero length periods are also considered invalid. Zero length periods are |
38 | periods where the begining and end points are the same, or, the given |
39 | duration is zero. For a zero length period, the last point will be one |
40 | unit less than the begining point. |
41 | |
42 | In the case that the begin and last are the same, the period has a |
43 | length of one unit. |
44 | |
45 | The best way to handle periods is usually to provide a begining point and |
46 | a duration. So, day1 + 7 days is a week period which includes all of the |
47 | first day and 6 more days (eg: Sun to Sat). |
48 | |
49 | */ |
50 | template<class point_rep, class duration_rep> |
51 | class period : private |
52 | boost::less_than_comparable<period<point_rep, duration_rep> |
53 | , boost::equality_comparable< period<point_rep, duration_rep> |
54 | > > |
55 | { |
56 | public: |
57 | typedef point_rep point_type; |
58 | typedef duration_rep duration_type; |
59 | |
60 | period(point_rep first_point, point_rep end_point); |
61 | period(point_rep first_point, duration_rep len); |
62 | point_rep begin() const; |
63 | point_rep end() const; |
64 | point_rep last() const; |
65 | duration_rep length() const; |
66 | bool is_null() const; |
67 | bool operator==(const period& rhs) const; |
68 | bool operator<(const period& rhs) const; |
69 | void shift(const duration_rep& d); |
70 | void expand(const duration_rep& d); |
71 | bool contains(const point_rep& point) const; |
72 | bool contains(const period& other) const; |
73 | bool intersects(const period& other) const; |
74 | bool is_adjacent(const period& other) const; |
75 | bool is_before(const point_rep& point) const; |
76 | bool is_after(const point_rep& point) const; |
77 | period intersection(const period& other) const; |
78 | period merge(const period& other) const; |
79 | period span(const period& other) const; |
80 | private: |
81 | point_rep begin_; |
82 | point_rep last_; |
83 | }; |
84 | |
85 | //! create a period from begin to last eg: [begin,end) |
86 | /*! If end <= begin then the period will be invalid |
87 | */ |
88 | template<class point_rep, class duration_rep> |
89 | inline |
90 | period<point_rep,duration_rep>::period(point_rep first_point, |
91 | point_rep end_point) : |
92 | begin_(first_point), |
93 | last_(end_point - duration_rep::unit()) |
94 | {} |
95 | |
96 | //! create a period as [begin, begin+len) |
97 | /*! If len is <= 0 then the period will be invalid |
98 | */ |
99 | template<class point_rep, class duration_rep> |
100 | inline |
101 | period<point_rep,duration_rep>::period(point_rep first_point, duration_rep len) : |
102 | begin_(first_point), |
103 | last_(first_point + len-duration_rep::unit()) |
104 | { } |
105 | |
106 | |
107 | //! Return the first element in the period |
108 | template<class point_rep, class duration_rep> |
109 | inline |
110 | point_rep period<point_rep,duration_rep>::begin() const |
111 | { |
112 | return begin_; |
113 | } |
114 | |
115 | //! Return one past the last element |
116 | template<class point_rep, class duration_rep> |
117 | inline |
118 | point_rep period<point_rep,duration_rep>::end() const |
119 | { |
120 | return last_ + duration_rep::unit(); |
121 | } |
122 | |
123 | //! Return the last item in the period |
124 | template<class point_rep, class duration_rep> |
125 | inline |
126 | point_rep period<point_rep,duration_rep>::last() const |
127 | { |
128 | return last_; |
129 | } |
130 | |
131 | //! True if period is ill formed (length is zero or less) |
132 | template<class point_rep, class duration_rep> |
133 | inline |
134 | bool period<point_rep,duration_rep>::is_null() const |
135 | { |
136 | return end() <= begin_; |
137 | } |
138 | |
139 | //! Return the length of the period |
140 | template<class point_rep, class duration_rep> |
141 | inline |
142 | duration_rep period<point_rep,duration_rep>::length() const |
143 | { |
144 | if(last_ < begin_){ // invalid period |
145 | return last_+duration_rep::unit() - begin_; |
146 | } |
147 | else{ |
148 | return end() - begin_; // normal case |
149 | } |
150 | } |
151 | |
152 | //! Equality operator |
153 | template<class point_rep, class duration_rep> |
154 | inline |
155 | bool period<point_rep,duration_rep>::operator==(const period& rhs) const |
156 | { |
157 | return ((begin_ == rhs.begin_) && |
158 | (last_ == rhs.last_)); |
159 | } |
160 | |
161 | //! Strict as defined by rhs.last <= lhs.last |
162 | template<class point_rep, class duration_rep> |
163 | inline |
164 | bool period<point_rep,duration_rep>::operator<(const period& rhs) const |
165 | { |
166 | return (last_ < rhs.begin_); |
167 | } |
168 | |
169 | |
170 | //! Shift the start and end by the specified amount |
171 | template<class point_rep, class duration_rep> |
172 | inline |
173 | void period<point_rep,duration_rep>::shift(const duration_rep& d) |
174 | { |
175 | begin_ = begin_ + d; |
176 | last_ = last_ + d; |
177 | } |
178 | |
179 | /** Expands the size of the period by the duration on both ends. |
180 | * |
181 | *So before expand |
182 | *@code |
183 | * |
184 | * [-------] |
185 | * ^ ^ ^ ^ ^ ^ ^ |
186 | * 1 2 3 4 5 6 7 |
187 | * |
188 | *@endcode |
189 | * After expand(2) |
190 | *@code |
191 | * |
192 | * [----------------------] |
193 | * ^ ^ ^ ^ ^ ^ ^ |
194 | * 1 2 3 4 5 6 7 |
195 | * |
196 | *@endcode |
197 | */ |
198 | template<class point_rep, class duration_rep> |
199 | inline |
200 | void period<point_rep,duration_rep>::expand(const duration_rep& d) |
201 | { |
202 | begin_ = begin_ - d; |
203 | last_ = last_ + d; |
204 | } |
205 | |
206 | //! True if the point is inside the period, zero length periods contain no points |
207 | template<class point_rep, class duration_rep> |
208 | inline |
209 | bool period<point_rep,duration_rep>::contains(const point_rep& point) const |
210 | { |
211 | return ((point >= begin_) && |
212 | (point <= last_)); |
213 | } |
214 | |
215 | |
216 | //! True if this period fully contains (or equals) the other period |
217 | template<class point_rep, class duration_rep> |
218 | inline |
219 | bool period<point_rep,duration_rep>::contains(const period<point_rep,duration_rep>& other) const |
220 | { |
221 | return ((begin_ <= other.begin_) && (last_ >= other.last_)); |
222 | } |
223 | |
224 | |
225 | //! True if periods are next to each other without a gap. |
226 | /* In the example below, p1 and p2 are adjacent, but p3 is not adjacent |
227 | * with either of p1 or p2. |
228 | *@code |
229 | * [-p1-) |
230 | * [-p2-) |
231 | * [-p3-) |
232 | *@endcode |
233 | */ |
234 | template<class point_rep, class duration_rep> |
235 | inline |
236 | bool |
237 | 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 |
255 | bool |
256 | period<point_rep,duration_rep>::is_after(const point_rep& t) const |
257 | { |
258 | if (is_null()) |
259 | { |
260 | return false; //null period isn't after |
261 | } |
262 | |
263 | return t < begin_; |
264 | } |
265 | |
266 | //! True if all of the period is prior to the passed point or end <= t |
267 | /* In the example below points 4 and 5 return true. |
268 | *@code |
269 | * [---------]) |
270 | * ^ ^ ^ ^ ^ |
271 | * 1 2 3 4 5 |
272 | * |
273 | *@endcode |
274 | */ |
275 | template<class point_rep, class duration_rep> |
276 | inline |
277 | bool |
278 | period<point_rep,duration_rep>::is_before(const point_rep& t) const |
279 | { |
280 | if (is_null()) |
281 | { |
282 | return false; //null period isn't before anything |
283 | } |
284 | |
285 | return last_ < t; |
286 | } |
287 | |
288 | |
289 | //! True if the periods overlap in any way |
290 | /* In the example below p1 intersects with p2, p4, and p6. |
291 | *@code |
292 | * [---p1---) |
293 | * [---p2---) |
294 | * [---p3---) |
295 | * [---p4---) |
296 | * [-p5-) |
297 | * [-p6-) |
298 | *@endcode |
299 | */ |
300 | template<class point_rep, class duration_rep> |
301 | inline |
302 | bool period<point_rep,duration_rep>::intersects(const period<point_rep,duration_rep>& other) const |
303 | { |
304 | return ( contains(other.begin_) || |
305 | other.contains(begin_) || |
306 | ((other.begin_ < begin_) && (other.last_ >= begin_))); |
307 | } |
308 | |
309 | //! Returns the period of intersection or invalid range no intersection |
310 | template<class point_rep, class duration_rep> |
311 | inline |
312 | period<point_rep,duration_rep> |
313 | period<point_rep,duration_rep>::intersection(const period<point_rep,duration_rep>& other) const |
314 | { |
315 | if (begin_ > other.begin_) { |
316 | if (last_ <= other.last_) { //case2 |
317 | return *this; |
318 | } |
319 | //case 1 |
320 | return period<point_rep,duration_rep>(begin_, other.end()); |
321 | } |
322 | else { |
323 | if (last_ <= other.last_) { //case3 |
324 | return period<point_rep,duration_rep>(other.begin_, this->end()); |
325 | } |
326 | //case4 |
327 | return other; |
328 | } |
329 | //unreachable |
330 | } |
331 | |
332 | //! Returns the union of intersecting periods -- or null period |
333 | /*! |
334 | */ |
335 | template<class point_rep, class duration_rep> |
336 | inline |
337 | period<point_rep,duration_rep> |
338 | period<point_rep,duration_rep>::merge(const period<point_rep,duration_rep>& other) const |
339 | { |
340 | if (this->intersects(other)) { |
341 | if (begin_ < other.begin_) { |
342 | return period<point_rep,duration_rep>(begin_, last_ > other.last_ ? this->end() : other.end()); |
343 | } |
344 | |
345 | return period<point_rep,duration_rep>(other.begin_, last_ > other.last_ ? this->end() : other.end()); |
346 | |
347 | } |
348 | return period<point_rep,duration_rep>(begin_,begin_); // no intersect return null |
349 | } |
350 | |
351 | //! Combine two periods with earliest start and latest end. |
352 | /*! Combines two periods and any gap between them such that |
353 | * start = min(p1.start, p2.start) |
354 | * end = max(p1.end , p2.end) |
355 | *@code |
356 | * [---p1---) |
357 | * [---p2---) |
358 | * result: |
359 | * [-----------p3----------) |
360 | *@endcode |
361 | */ |
362 | template<class point_rep, class duration_rep> |
363 | inline |
364 | period<point_rep,duration_rep> |
365 | period<point_rep,duration_rep>::span(const period<point_rep,duration_rep>& other) const |
366 | { |
367 | point_rep start((begin_ < other.begin_) ? begin() : other.begin()); |
368 | point_rep newend((last_ < other.last_) ? other.end() : this->end()); |
369 | return period<point_rep,duration_rep>(start, newend); |
370 | } |
371 | |
372 | |
373 | } } //namespace date_time |
374 | |
375 | |
376 | |
377 | #endif |
378 | |