DateTime::SpanSet - set of DateTime spans

    $spanset = DateTime::SpanSet->from_spans( spans => [ $dt_span, $dt_span ] );

    $set = $spanset->union( $set2 );         # like "OR", "insert", "both"
    $set = $spanset->complement( $set2 );    # like "delete", "remove"
    $set = $spanset->intersection( $set2 );  # like "AND", "while"
    $set = $spanset->complement;             # like "NOT", "negate", "invert"

    if ( $spanset->intersects( $set2 ) ) { ...  # like "touches", "interferes"
    if ( $spanset->contains( $set2 ) ) { ...    # like "is-fully-inside"

    # data extraction 
    $date = $spanset->min;           # first date of the set
    $date = $spanset->max;           # last date of the set

    $iter = $spanset->iterator;
    while ( $dt = $iter->next ) {
        # $dt is a DateTime::Span
        print $dt->start->ymd;   # first date of span
        print $dt->end->ymd;     # last date of span
    };

DateTime::SpanSet is a class that represents sets of datetime spans. An example would be a recurring meeting that occurs from 13:00-15:00 every Friday.

* from_spans

Creates a new span set from one or more CWDateTime::Span objects.

   $spanset = DateTime::SpanSet->from_spans( spans => [ $dt_span ] );

* from_set_and_duration

Creates a new span set from one or more CWDateTime::Set objects and a duration. The duration can be a CWDateTime::Duration object, or the parameters to create a new CWDateTime::Duration object, such as days, months, etc.

   $spanset =
       DateTime::SpanSet->from_set_and_duration
           ( set => $dt_set, days => 1 );

* from_sets

Creates a new span set from two CWDateTime::Set objects. One set defines the starting dates, and the other defines the end dates.

   $spanset =
       DateTime::SpanSet->from_sets
           ( start_set => $dt_set1, end_set => $dt_set2 );

The spans have the starting date CWclosed, and the end date CWopen, like in CW[$dt1, $dt2). If an end date comes without a starting date before it, then it defines a span like CW(-inf, $dt). If a starting date comes without an end date after it, then it defines a span like CW[$dt, inf).

* empty_set

Creates a new empty set.

* clone

This object method returns a replica of the given object. This method accepts either a time zone object or a string that can be passed as the name parameter to CWDateTime::TimeZone->new(). If the new time zone's offset is different from the old time zone, then the local time is adjusted accordingly. If the old time zone was a floating time zone, then no adjustments to the local time are made, except to account for leap seconds. If the new time zone is floating, then the UTC time is adjusted in order to leave the local time untouched.

* min

* max

First or last dates in the set. These methods may return CWundef if the set is empty. It is also possible that these methods may return a scalar containing infinity or negative infinity.

* duration

The total size of the set, as a CWDateTime::Duration object. The duration may be infinite. Also available as CWsize().

* span

The total span of the set, as a CWDateTime::Span object.

* next

  my $span = $set->next( $dt );

This method is used to find the next span in the set, after a given datetime or span. The return value is a CWDateTime::Span, or CWundef if there is no matching span in the set.

* previous

  my $span = $set->previous( $dt );

This method is used to find the previous span in the set, before a given datetime or span. The return value is a CWDateTime::Span, or CWundef if there is no matching span in the set.

* current

  my $span = $set->current( $dt );

This method is used to find the current span in the set, that intersects a given datetime or span. If no current span is found, then the previous span is returned. The return value is a CWDateTime::SpanSet, or CWundef if there is no matching span in the set. If a span parameter is given, it may happen that current returns more than one span. See also: CWintersected_spans() method.

* closest

  my $span = $set->closest( $dt );

This method is used to find the closest span in the set, given a datetime or span. The return value is a CWDateTime::SpanSet, or CWundef if the set is empty. If a span parameter is given, it may happen that closest returns more than one span.

* as_list

Returns a list of CWDateTime::Span objects.

  my @dt = $set->as_list( span => $span );

Just as with the CWiterator() method, the CWas_list() method can be limited by a span. If a set is specified as a recurrence and has no fixed begin and end datetimes, then CWas_list will return CWundef unless you limit it with a span. Please note that this is explicitly not an empty list, since an empty list is a valid return value for empty sets!

* union

* intersection

* complement

Set operations may be performed not only with CWDateTime::SpanSet objects, but also with CWDateTime, CWDateTime::Set and CWDateTime::Span objects. These set operations always return a CWDateTime::SpanSet object.

    $set = $spanset->union( $set2 );         # like "OR", "insert", "both"
    $set = $spanset->complement( $set2 );    # like "delete", "remove"
    $set = $spanset->intersection( $set2 );  # like "AND", "while"
    $set = $spanset->complement;             # like "NOT", "negate", "invert"

* intersected_spans

This method can accept a CWDateTime list, a CWDateTime::Set, a CWDateTime::Span, or a CWDateTime::SpanSet object as an argument.

    $set = $set1->intersected_spans( $set2 );

The method always returns a CWDateTime::SpanSet object, containing all spans that are intersected by the given set. Unlike the CWintersection method, the spans are not modified. See diagram below:

               set1   [....]   [....]   [....]   [....]
               set2      [................]

       intersection      [.]   [....]   [.]

  intersected_spans   [....]   [....]   [....]

* intersects

* contains

These set functions return a boolean value.

    if ( $spanset->intersects( $set2 ) ) { ...  # like "touches", "interferes"
    if ( $spanset->contains( $dt ) ) { ...    # like "is-fully-inside"

These methods can accept a CWDateTime, CWDateTime::Set, CWDateTime::Span, or CWDateTime::SpanSet object as an argument.

* iterator / next / previous

This method can be used to iterate over the spans in a set.

    $iter = $spanset->iterator;
    while ( $dt = $iter->next ) {
        # $dt is a DateTime::Span
        print $dt->min->ymd;   # first date of span
        print $dt->max->ymd;   # last date of span
    }

The boundaries of the iterator can be limited by passing it a CWspan parameter. This should be a CWDateTime::Span object which delimits the iterator's boundaries. Optionally, instead of passing an object, you can pass any parameters that would work for one of the CWDateTime::Span class's constructors, and an object will be created for you. Obviously, if the span you specify does is not restricted both at the start and end, then your iterator may iterate forever, depending on the nature of your set. User beware! The CWnext() or CWprevious() methods will return CWundef when there are no more spans in the iterator.

* start_set

* end_set

These methods do the inverse of the CWfrom_sets method: CWstart_set retrieves a DateTime::Set with the start datetime of each span. CWend_set retrieves a DateTime::Set with the end datetime of each span.

* map ( sub { ... } )

    # example: enlarge the spans
    $set = $set2->map( 
        sub {
            my $start = $_->start;
            my $end = $_->end;
            return DateTime::Span->from_datetimes(
                start => $start,
                before => $end,
            );
        }
    );

This method is the set version of Perl map. It evaluates a subroutine for each element of the set (locally setting $_ to each DateTime::Span) and returns the set composed of the results of each such evaluation. Like Perl map, each element of the set may produce zero, one, or more elements in the returned value. Unlike Perl map, changing $_ does not change the original set. This means that calling map in void context has no effect. The callback subroutine may not be called immediately. Don't count on subroutine side-effects. For example, a CWprint inside the subroutine may happen later than you expect. The callback return value is expected to be within the span of the CWprevious and the CWnext element in the original set. For example: given the set CW[ 2001, 2010, 2015 ], the callback result for the value CW2010 is expected to be within the span CW[ 2001 .. 2015 ].

* grep ( sub { ... } )

    # example: filter out all spans happening today
    my $today = DateTime->today;
    $set = $set2->grep( 
        sub {
            return ( ! $_->contains( $today ) );
        }
    );

This method is the set version of Perl grep. It evaluates a subroutine for each element of the set (locally setting $_ to each DateTime::Span) and returns the set consisting of those elements for which the expression evaluated to true. Unlike Perl grep, changing $_ does not change the original set. This means that calling grep in void context has no effect. Changing $_ does change the resulting set. The callback subroutine may not be called immediately. Don't count on subroutine side-effects. For example, a CWprint inside the subroutine may happen later than you expect.

* iterate

Internal method - use map or grep instead. This function apply a callback subroutine to all elements of a set and returns the resulting set. The parameter CW$_[0] to the callback subroutine is a CWDateTime::Span object. If the callback returns CWundef, the datetime is removed from the set:

    sub remove_sundays {
        $_[0] unless $_[0]->start->day_of_week == 7;
    }

The callback return value is expected to be within the span of the CWprevious and the CWnext element in the original set. For example: given the set CW[ 2001, 2010, 2015 ], the callback result for the value CW2010 is expected to be within the span CW[ 2001 .. 2015 ]. The callback subroutine may not be called immediately. Don't count on subroutine side-effects. For example, a CWprint inside the subroutine may happen later than you expect.

Support is offered through the CWdatetime@perl.org mailing list.

Please report bugs using rt.cpan.org

Flavio Soibelmann Glock <fglock@pucrs.br>

The API was developed together with Dave Rolsky and the DateTime Community.

Copyright (c) 2003 Flavio Soibelmann Glock. All rights reserved. This program is free software; you can distribute it and/or modify it under the same terms as Perl itself.

The full text of the license can be found in the LICENSE file included with this module.

Set::Infinite

For details on the Perl DateTime Suite project please see <http://datetime.perl.org>.