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Class template period

boost::date_time::period — Provides generalized period type useful in date-time systems.

Synopsis

template<typename point_rep, typename duration_rep> 
class period {
public:
  // types
  typedef point_rep    point_type;   
  typedef duration_rep duration_type;

  // construct/copy/destruct
  period(point_rep, point_rep);
  period(point_rep, duration_rep);

  // public member functions
  point_rep begin() const;
  point_rep end() const;
  point_rep last() const;
  duration_rep length() const;
  bool is_null() const;
  bool operator==(const period &) const;
  bool operator<(const period &) const;
  void shift(const duration_rep &) ;
  void expand(const duration_rep &) ;
  bool contains(const point_rep &) const;
  bool contains(const period &) const;
  bool intersects(const period &) const;
  bool is_adjacent(const period &) const;
  bool is_before(const point_rep &) const;
  bool is_after(const point_rep &) const;
  period intersection(const period &) const;
  period merge(const period &) const;
  period span(const period &) const;
};

Description

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).

period public construct/copy/destruct

  1. period(point_rep first_point, point_rep end_point);

    If end <= begin then the period will be invalid

  2. period(point_rep first_point, duration_rep len);

    If len is <= 0 then the period will be invalid

period public member functions

  1. point_rep begin() const;
  2. point_rep end() const;
  3. point_rep last() const;
  4. duration_rep length() const;
  5. bool is_null() const;
  6. bool operator==(const period & rhs) const;
  7. bool operator<(const period & rhs) const;
  8. void shift(const duration_rep & d) ;
  9. void expand(const duration_rep & d) ;

    Expands the size of the period by the duration on both ends.

    So before expand

             [-------]
     ^   ^   ^   ^   ^   ^  ^
     1   2   3   4   5   6  7
     
       *
    

    After expand(2)

     [----------------------]
     ^   ^   ^   ^   ^   ^  ^
     1   2   3   4   5   6  7
     
       *
    

  10. bool contains(const point_rep & point) const;
  11. bool contains(const period & other) const;
  12. bool intersects(const period & other) const;
  13. bool is_adjacent(const period & other) const;
  14. bool is_before(const point_rep & point) const;
  15. bool is_after(const point_rep & point) const;
  16. period intersection(const period & other) const;
  17. period merge(const period & other) const;
  18. period span(const period & other) const;

    Combines two periods and any gap between them such that start = min(p1.start, p2.start) end = max(p1.end , p2.end)

            [---p1---)
                           [---p2---)
     result:
            [-----------p3----------) 
       *
    


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