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.
Creates a new span set from one or more DateTime::Span objects.
$spanset = DateTime::SpanSet->from_spans( spans => [ $dt_span ] );
Creates a new span set from one or more DateTime::Set objects and a
duration.
The duration can be a DateTime::Duration object, or the parameters
to create a new DateTime::Duration object, such as "days",
"months", etc.
$spanset =
DateTime::SpanSet->from_set_and_duration
( set => $dt_set, days => 1 );
Creates a new span set from two DateTime::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 => $dt_set2 );
The spans have the starting date closed, and the end date open,
like in [$dt1, $dt2).
If an end date comes without a starting date before it, then it
defines a span like (-inf, $dt).
If a starting date comes without an end date after it, then it defines
a span like [$dt, inf).
This method accepts either a time zone object or a string that can be
passed as the "name" parameter to DateTime::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.
undef if
the set is empty. It is also possible that these methods may return a
scalar containing infinity or negative infinity.
The total size of the set, as a DateTime::Duration object.
The duration may be infinite.
Also available as size().
DateTime::Span object.
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 DateTime::Span, or undef if there is no matching
span in the set.
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 DateTime::Span, or undef if there is no matching
span in the set.
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 DateTime::SpanSet, or undef 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: intersected_spans() method.
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 DateTime::SpanSet, or undef if the
set is empty.
If a span parameter is given, it may happen that "closest" returns more than one span.
Returns a list of DateTime::Span objects.
my @dt_span = $set->as_list( span => $span );
Just as with the iterator() method, the as_list() method can be
limited by a span.
Applying as_list() to a large recurring spanset is a very expensive operation,
both in CPU time and in the memory used.
For this reason, when as_list() operates on large recurrence sets, it will
return at most approximately 200 spans. For larger sets, and for infinite
sets, as_list() will return undef.
Please note that this is explicitly not an empty list, since an empty list is a valid return value for empty sets!
If you really need to extract spans from a large set, you can:
- limit the set with a shorter span:
my @short_list = $large_set->as_list( span => $short_span );
- use an iterator:
my @large_list;
my $iter = $large_set->iterator;
push @large_list, $dt while $dt = $iter->next;
Set operations may be performed not only with DateTime::SpanSet
objects, but also with DateTime, DateTime::Set and
DateTime::Span objects. These set operations always return a
DateTime::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"
This method can accept a DateTime list,
a DateTime::Set, a DateTime::Span, or a DateTime::SpanSet
object as an argument.
$set = $set1->intersected_spans( $set2 );
The method always returns a DateTime::SpanSet object,
containing all spans that are intersected by the given set.
Unlike the intersection method, the spans are not modified.
See diagram below:
set1 [....] [....] [....] [....]
set2 [................]
intersection [.] [....] [.]
intersected_spans [....] [....] [....]
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 DateTime, DateTime::Set,
DateTime::Span, or DateTime::SpanSet object as an argument.
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 span
parameter. This should be a DateTime::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
DateTime::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 next() or previous() methods will return undef
when there are no more spans in the iterator.
These methods do the inverse of the from_sets method:
start_set retrieves a DateTime::Set with the start datetime of each span.
end_set retrieves a DateTime::Set with the end datetime of each span.
# 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 print inside the subroutine may happen later than you expect.
The callback return value is expected to be within the span of the
previous and the next element in the original set.
For example: given the set [ 2001, 2010, 2015 ],
the callback result for the value 2010 is expected to be
within the span [ 2001 .. 2015 ].
# 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 print inside the subroutine may happen later than you expect.
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 $_[0] to the callback subroutine is a DateTime::Span
object.
If the callback returns undef, 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
previous and the next element in the original set.
For example: given the set [ 2001, 2010, 2015 ],
the callback result for the value 2010 is expected to be
within the span [ 2001 .. 2015 ].
The callback subroutine may not be called immediately.
Don't count on subroutine side-effects. For example,
a print inside the subroutine may happen later than you expect.
Support is offered through the datetime@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.