| #ifndef DATE_TIME_PERIOD_HPP___ |
| #define DATE_TIME_PERIOD_HPP___ |
| |
| /* Copyright (c) 2002,2003 CrystalClear Software, Inc. |
| * Use, modification and distribution is subject to the |
| * Boost Software License, Version 1.0. (See accompanying |
| * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt) |
| * Author: Jeff Garland, Bart Garst |
| * $Date: 2008-02-27 15:00:24 -0500 (Wed, 27 Feb 2008) $ |
| */ |
| |
| /*! \file period.hpp |
| This file contain the implementation of the period abstraction. This is |
| basically the same idea as a range. Although this class is intended for |
| use in the time library, it is pretty close to general enough for other |
| numeric uses. |
| |
| */ |
| |
| #include "boost/operators.hpp" |
| |
| |
| namespace boost { |
| namespace date_time { |
| //!Provides generalized period type useful in date-time systems |
| /*!This template uses a class to represent a time point within the period |
| and another class to represent a duration. As a result, this class is |
| not appropriate for use when the number and duration representation |
| are the same (eg: in the regular number domain). |
| |
| A period can be specified by providing either the begining point and |
| a duration or the begining point and the end point( end is NOT part |
| of the period but 1 unit past it. A period will be "invalid" if either |
| end_point <= begin_point or the given duration is <= 0. Any valid period |
| will return false for is_null(). |
| |
| Zero length periods are also considered invalid. Zero length periods are |
| periods where the begining and end points are the same, or, the given |
| duration is zero. For a zero length period, the last point will be one |
| unit less than the begining point. |
| |
| In the case that the begin and last are the same, the period has a |
| length of one unit. |
| |
| The best way to handle periods is usually to provide a begining point and |
| a duration. So, day1 + 7 days is a week period which includes all of the |
| first day and 6 more days (eg: Sun to Sat). |
| |
| */ |
| template<class point_rep, class duration_rep> |
| class period : private |
| boost::less_than_comparable<period<point_rep, duration_rep> |
| , boost::equality_comparable< period<point_rep, duration_rep> |
| > > |
| { |
| public: |
| typedef point_rep point_type; |
| typedef duration_rep duration_type; |
| |
| period(point_rep first_point, point_rep end_point); |
| period(point_rep first_point, duration_rep len); |
| point_rep begin() const; |
| point_rep end() const; |
| point_rep last() const; |
| duration_rep length() const; |
| bool is_null() const; |
| bool operator==(const period& rhs) const; |
| bool operator<(const period& rhs) const; |
| void shift(const duration_rep& d); |
| void expand(const duration_rep& d); |
| bool contains(const point_rep& point) const; |
| bool contains(const period& other) const; |
| bool intersects(const period& other) const; |
| bool is_adjacent(const period& other) const; |
| bool is_before(const point_rep& point) const; |
| bool is_after(const point_rep& point) const; |
| period intersection(const period& other) const; |
| period merge(const period& other) const; |
| period span(const period& other) const; |
| private: |
| point_rep begin_; |
| point_rep last_; |
| }; |
| |
| //! create a period from begin to last eg: [begin,end) |
| /*! If end <= begin then the period will be invalid |
| */ |
| template<class point_rep, class duration_rep> |
| inline |
| period<point_rep,duration_rep>::period(point_rep first_point, |
| point_rep end_point) : |
| begin_(first_point), |
| last_(end_point - duration_rep::unit()) |
| {} |
| |
| //! create a period as [begin, begin+len) |
| /*! If len is <= 0 then the period will be invalid |
| */ |
| template<class point_rep, class duration_rep> |
| inline |
| period<point_rep,duration_rep>::period(point_rep first_point, duration_rep len) : |
| begin_(first_point), |
| last_(first_point + len-duration_rep::unit()) |
| { } |
| |
| |
| //! Return the first element in the period |
| template<class point_rep, class duration_rep> |
| inline |
| point_rep period<point_rep,duration_rep>::begin() const |
| { |
| return begin_; |
| } |
| |
| //! Return one past the last element |
| template<class point_rep, class duration_rep> |
| inline |
| point_rep period<point_rep,duration_rep>::end() const |
| { |
| return last_ + duration_rep::unit(); |
| } |
| |
| //! Return the last item in the period |
| template<class point_rep, class duration_rep> |
| inline |
| point_rep period<point_rep,duration_rep>::last() const |
| { |
| return last_; |
| } |
| |
| //! True if period is ill formed (length is zero or less) |
| template<class point_rep, class duration_rep> |
| inline |
| bool period<point_rep,duration_rep>::is_null() const |
| { |
| return end() <= begin_; |
| } |
| |
| //! Return the length of the period |
| template<class point_rep, class duration_rep> |
| inline |
| duration_rep period<point_rep,duration_rep>::length() const |
| { |
| if(last_ < begin_){ // invalid period |
| return last_+duration_rep::unit() - begin_; |
| } |
| else{ |
| return end() - begin_; // normal case |
| } |
| } |
| |
| //! Equality operator |
| template<class point_rep, class duration_rep> |
| inline |
| bool period<point_rep,duration_rep>::operator==(const period& rhs) const |
| { |
| return ((begin_ == rhs.begin_) && |
| (last_ == rhs.last_)); |
| } |
| |
| //! Strict as defined by rhs.last <= lhs.last |
| template<class point_rep, class duration_rep> |
| inline |
| bool period<point_rep,duration_rep>::operator<(const period& rhs) const |
| { |
| return (last_ < rhs.begin_); |
| } |
| |
| |
| //! Shift the start and end by the specified amount |
| template<class point_rep, class duration_rep> |
| inline |
| void period<point_rep,duration_rep>::shift(const duration_rep& d) |
| { |
| begin_ = begin_ + d; |
| last_ = last_ + d; |
| } |
| |
| /** Expands the size of the period by the duration on both ends. |
| * |
| *So before expand |
| *@code |
| * |
| * [-------] |
| * ^ ^ ^ ^ ^ ^ ^ |
| * 1 2 3 4 5 6 7 |
| * |
| *@endcode |
| * After expand(2) |
| *@code |
| * |
| * [----------------------] |
| * ^ ^ ^ ^ ^ ^ ^ |
| * 1 2 3 4 5 6 7 |
| * |
| *@endcode |
| */ |
| template<class point_rep, class duration_rep> |
| inline |
| void period<point_rep,duration_rep>::expand(const duration_rep& d) |
| { |
| begin_ = begin_ - d; |
| last_ = last_ + d; |
| } |
| |
| //! True if the point is inside the period, zero length periods contain no points |
| template<class point_rep, class duration_rep> |
| inline |
| bool period<point_rep,duration_rep>::contains(const point_rep& point) const |
| { |
| return ((point >= begin_) && |
| (point <= last_)); |
| } |
| |
| |
| //! True if this period fully contains (or equals) the other period |
| template<class point_rep, class duration_rep> |
| inline |
| bool period<point_rep,duration_rep>::contains(const period<point_rep,duration_rep>& other) const |
| { |
| return ((begin_ <= other.begin_) && (last_ >= other.last_)); |
| } |
| |
| |
| //! True if periods are next to each other without a gap. |
| /* In the example below, p1 and p2 are adjacent, but p3 is not adjacent |
| * with either of p1 or p2. |
| *@code |
| * [-p1-) |
| * [-p2-) |
| * [-p3-) |
| *@endcode |
| */ |
| template<class point_rep, class duration_rep> |
| inline |
| bool |
| period<point_rep,duration_rep>::is_adjacent(const period<point_rep,duration_rep>& other) const |
| { |
| return (other.begin() == end() || |
| begin_ == other.end()); |
| } |
| |
| |
| //! True if all of the period is prior or t < start |
| /* In the example below only point 1 would evaluate to true. |
| *@code |
| * [---------]) |
| * ^ ^ ^ ^ ^ |
| * 1 2 3 4 5 |
| * |
| *@endcode |
| */ |
| template<class point_rep, class duration_rep> |
| inline |
| bool |
| period<point_rep,duration_rep>::is_after(const point_rep& t) const |
| { |
| if (is_null()) |
| { |
| return false; //null period isn't after |
| } |
| |
| return t < begin_; |
| } |
| |
| //! True if all of the period is prior to the passed point or end <= t |
| /* In the example below points 4 and 5 return true. |
| *@code |
| * [---------]) |
| * ^ ^ ^ ^ ^ |
| * 1 2 3 4 5 |
| * |
| *@endcode |
| */ |
| template<class point_rep, class duration_rep> |
| inline |
| bool |
| period<point_rep,duration_rep>::is_before(const point_rep& t) const |
| { |
| if (is_null()) |
| { |
| return false; //null period isn't before anything |
| } |
| |
| return last_ < t; |
| } |
| |
| |
| //! True if the periods overlap in any way |
| /* In the example below p1 intersects with p2, p4, and p6. |
| *@code |
| * [---p1---) |
| * [---p2---) |
| * [---p3---) |
| * [---p4---) |
| * [-p5-) |
| * [-p6-) |
| *@endcode |
| */ |
| template<class point_rep, class duration_rep> |
| inline |
| bool period<point_rep,duration_rep>::intersects(const period<point_rep,duration_rep>& other) const |
| { |
| return ( contains(other.begin_) || |
| other.contains(begin_) || |
| ((other.begin_ < begin_) && (other.last_ >= begin_))); |
| } |
| |
| //! Returns the period of intersection or invalid range no intersection |
| template<class point_rep, class duration_rep> |
| inline |
| period<point_rep,duration_rep> |
| period<point_rep,duration_rep>::intersection(const period<point_rep,duration_rep>& other) const |
| { |
| if (begin_ > other.begin_) { |
| if (last_ <= other.last_) { //case2 |
| return *this; |
| } |
| //case 1 |
| return period<point_rep,duration_rep>(begin_, other.end()); |
| } |
| else { |
| if (last_ <= other.last_) { //case3 |
| return period<point_rep,duration_rep>(other.begin_, this->end()); |
| } |
| //case4 |
| return other; |
| } |
| //unreachable |
| } |
| |
| //! Returns the union of intersecting periods -- or null period |
| /*! |
| */ |
| template<class point_rep, class duration_rep> |
| inline |
| period<point_rep,duration_rep> |
| period<point_rep,duration_rep>::merge(const period<point_rep,duration_rep>& other) const |
| { |
| if (this->intersects(other)) { |
| if (begin_ < other.begin_) { |
| return period<point_rep,duration_rep>(begin_, last_ > other.last_ ? this->end() : other.end()); |
| } |
| |
| return period<point_rep,duration_rep>(other.begin_, last_ > other.last_ ? this->end() : other.end()); |
| |
| } |
| return period<point_rep,duration_rep>(begin_,begin_); // no intersect return null |
| } |
| |
| //! Combine two periods with earliest start and latest end. |
| /*! Combines two periods and any gap between them such that |
| * start = min(p1.start, p2.start) |
| * end = max(p1.end , p2.end) |
| *@code |
| * [---p1---) |
| * [---p2---) |
| * result: |
| * [-----------p3----------) |
| *@endcode |
| */ |
| template<class point_rep, class duration_rep> |
| inline |
| period<point_rep,duration_rep> |
| period<point_rep,duration_rep>::span(const period<point_rep,duration_rep>& other) const |
| { |
| point_rep start((begin_ < other.begin_) ? begin() : other.begin()); |
| point_rep newend((last_ < other.last_) ? other.end() : this->end()); |
| return period<point_rep,duration_rep>(start, newend); |
| } |
| |
| |
| } } //namespace date_time |
| |
| |
| |
| #endif |