DateTime::SpanSet(3) User Contributed Perl Documentation DateTime::SpanSet(3)NAMEDateTime::SpanSet - set of DateTime spans
SYNOPSIS
$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
};
DESCRIPTION
"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.
This is different from a "DateTime::Set", which is made of individual
datetime points as opposed to ranges.
METHODS
· from_spans
Creates a new span set from one or more "DateTime::Span" objects.
$spanset = DateTime::SpanSet->from_spans( spans => [ $dt_span ] );
· from_set_and_duration
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 );
· from_sets
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)".
· empty_set
Creates a new empty set.
· clone
This object method returns a replica of the given object.
· set_time_zone( $tz )
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.
· min
· max
First or last dates in the set. These methods may return "undef"
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 "DateTime::Duration" object.
The duration may be infinite.
Also available as "size()".
· span
The total span of the set, as a "DateTime::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 "DateTime::Span", or "undef" 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 "DateTime::Span", or "undef" 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 "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.
· 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 "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.
· as_list
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;
· union
· intersection
· complement
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"
· intersected_spans
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 [....] [....] [....]
· 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 "DateTime", "DateTime::Set",
"DateTime::Span", or "DateTime::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
"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.
· start_set
· end_set
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.
· 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 "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 ]".
· 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 "print" 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 $_[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
Support is offered through the "datetime@perl.org" mailing list.
Please report bugs using rt.cpan.org
AUTHOR
Flavio Soibelmann Glock <fglock@pucrs.br>
The API was developed together with Dave Rolsky and the DateTime
Community.
COPYRIGHT
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.
SEE ALSO
Set::Infinite
For details on the Perl DateTime Suite project please see
<http://datetime.perl.org>.
perl v5.14.1 2011-07-20 DateTime::SpanSet(3)
