NAME
DateTimeX::ISO8601::Interval - Provides a means of parsing and
manipulating ISO-8601 intervals and durations.
VERSION
version 0.004
SYNOPSIS
my $interval = DateTimeX::ISO8601::Interval->parse("2013-12-01/15");
$interval->contains('2013-12-07'); # true
$interval->contains('2013-12-16'); # false
my $repeating_interval = DateTimeX::ISO8601::Interval->parse("R12/2013-12-01/P1M");
my $iterator = $repeating_interval->iterator;
while(my $month_interval = $iterator->()){
# $month_interval is jan, feb, mar, ..., dec
}
DESCRIPTION
This module provides parsing and iteration functionality for "ISO 8601"
date/time intervals. The "ISO 8601" standard provides a succinct way of
representing an interval of time (including the option for the interval
to repeate).
According to Wikipedia, there are four ways to represent an interval:
* Start and end, such as "2007-03-01T13:00:00Z/2008-05-11T15:30:00Z"
* Start and duration, such as "2007-03-01T13:00:00Z/P1Y2M10DT2H30M"
* Duration and end, such as "P1Y2M10DT2H30M/2008-05-11T15:30:00Z"
* Duration only, such as "P1Y2M10DT2H30M", with additional context
information
METHODS
parse
This class method will parse the first argument provided as an "ISO
8601" formatted date/time interval. All remaining arguments will be
passed through to "/new". Example intervals are show above in the
"SYNOPSIS" and "DESCRIPTION".
new
The constructor takes a number of arguments and can be used instead of
"parse" to create a DateTimeX::ISO8601::Interval object. Those arguments
are:
* start - DateTime object, must be specified if "duration" is not
specified
* end - DateTime object, must be specified if "duration" is not
specified
* duration - DateTime::Duration object, must be specified if either
"start" or "end" is missing
* time_zone - string or DateTime::TimeZone object, will be set on
underlying DateTime objects if "start" or "end" values must be
parsed.
* abbreviate - boolean, enable (or disable) abbreviation. Defaults to
0
* repeat - integer, specify the number of times this interval should
be repeated. A value of -1 indicates an unbounded nubmer of repeats.
Defaults to 0.
start
Returns a DateTime object representing the beginning of this interval.
Note: if the interval doesn't include a time component, the start time
will actually be "00:00:00.000" of the following day (since the interval
covers the entire day). Intervals include the "start" value (in contrast
to the "end" value).
This interval can be changed by providing a new DateTime object as an
argument to this method. If this interval has an explicit "end" date
specified, any existing relative "duration" will be cleared.
end
Returns a DateTime object representing the end of this interval. This
value is exclusive meaning that the interval ends at exactly this time
and does not include this point in time. For instance, an interval that
is one hour long might begin at "09:38:43" and end at "10:38:43". The
"10:38:43" instant is not a part of this interval. Stated another way,
"$interval->contains($interval->end)" always returns false.
This interval can be changed by providing a new DateTime object as an
argument to this method. If this interval has an explicit "start" date
specified, any existing relative "duration" will be cleared.
Note: if the interval doesn't include a time component, the end time
will actually be "00:00:00.000" of the following day (since the interval
covers the entire day). If DateTime supported a time of day like
"24:00:00.000" that would be used instead.
duration
Returns a DateTime::Duration object representing this interval.
repeat
Returns the number of times this interval should repeat. This value can
be changed by providing a new value. A "repeat" value of 0 means that
the interval is not repeated. A "repeat" value of -1 means that the
interval should be repeated indefinitely.
iterator
Provides an iterator (as a code ref) that returns new
DateTimeX::ISO8601::Interval objects for each repitition as defined by
this interval object. Once all the intervals have been returned, the
iterator will return "undef" for each subsequent call.
A few arguments may be specified to modify the behavior of the iterator:
* skip - specify the number of intervals to skip for the first call to
the iterator
* after - skip all intervals that are before this DateTime object if
this DateTimeX::ISO8601::Interval is defined only by a duration
(having neither an explicit start or end date) this parameter will
be used as the start date.
* until - specify a specific DateTime to stop returning new intervals.
Similar to "end", this attribute is exclusive. That is, once the
iterator reaches a point where the interval being returned
"contains" this value, an "undef" is returned and the iterator stops
returning new intervals.
The iterator returned optionally accepts a single argument that can be
used to indicate the number of iterations to skip on that call. For
instance:
my $monthly = DateTimeX::ISO8601::Interval->parse('R12/2013-01-01/P1M');
my $iterator = $monthly->iterator;
while(my $month = $iterator->(2)) {
# $month would be Feb, Apr, Jun, etc
}
contains
Returns a boolean indicating whether the provided date (either an "ISO
8601" formatted string or a DateTime object) is between the "start" or
"end" dates as defined by this interval.
abbreviate
Enables abbreviated formatting where duplicate portions of the interval
are eliminated in the second half of the formatted string. To disable,
call "$interval-"abbreviate(0)>. See the "format" method for more
information
format
Returns the string representation of this object. You may optionally
specify "abbreviate => 1" to abbreviate the interval if possible. For
instance, "2013-12-01/2013-12-10" can be abbreviated to "2013-12-01/10".
If the interval does not appear to be eligible for abbreviation, it will
be returned in its full form.
set_time_zone
Sets the time_zone on the underlying DateTime objects contained in this
interval (see "set_time_zone" in DateTime). Also stores the time zone in
$self for future use by "contains".
CAVEATS
Partial dates and date/times
The "ISO 8601" spec is very complex. This module relies on
DateTime::Format::ISO8601 for parsing the necessary date strings and
should work well in most cases but some specific aspects of "ISO 8601"
are not well supported, specifically as it relates to partial
representations of dates.
For example, "2013-01/12" should last from January through December of
2013. This is parsed correctly but since DateTime defaults un-specified
portions of a date to the first valid value, the actual interval ends up
being from 2013-01-01 through 2013-12-01. Similarly, "2013/2014" should
last from the beginning of the year 2013 through the entire year of
2014. The interval is actually parsed as "2013-01-01/2014-01-01".
Because of the above, it is recommended that you only use full date and
date/time representations with this module (i.e. "yyyy-MM-dd" or
"yyyy-MM-ddTHH:mm::ss").
Representing dates with DateTime objects
The DateTime set of modules is very robust and a great way of handling
date/times in Perl. However, one of the ambiguities is that there is no
way of representing a date without an explicit time as well. This is
significant when parsing an interval that specifies only dates. For
instance: "2013-12-01/2013-12-07" should represent an interval lasting
from "2013-12-01" through the end of "2013-12-07". To accomplish this,
the end date is adjusted by one day such that "$interval->end" returns
the DateTime object that represents the time the interval ends:
"2013-12-08T00:00:00"
Decimal representation of durations
The "ISO 8601" standard allows for durations to be specified using
decimal notation (i.e. P0.5Y == P6M). While this works somewhat using
DateTime::Duration it's not robust enough to provide any support for
this portion of the standard.
Round-tripping intervals
The "ISO 8601" standard allows for intervals to be abbreviated such that
"2013-12-01/05" is equivalent to "2013-12-01/2013-12-05". Abbreviated
intervals should be parsed correctly but by default, when string-ified,
they are output in their expanded form. If you would like an abbreviated
form (if any abbreviation is determined to be possibile) you can use the
"abbreviate" method. Even so, the abbreviated form is not guaranteed to
be identical to what was provided on input.
AUTHOR
Brian Phillips <bphillips@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2013 by Brian Phillips and Shutterstock,
Inc.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.