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 &) ;
  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` construct/copy/destruct

period(point_rep first_point, point_rep end_point);

If end <= begin then the period will be invalid

period(point_rep first_point, duration_rep len);

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

`period` 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 & rhs) const;

bool operator<(const period & rhs) const;

```
void shift(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;

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----------) 
   *