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.