SYNOPSIS

    Use English:

     use DateTime::Format::Alami::EN;
     my $parser = DateTime::Format::Alami::EN->new();
     my $dt;
     $dt = $parser->parse_datetime("2 hours 13 minutes from now");
     $dt = $parser->parse_datetime("yesterday");

    use Indonesian:

     use DateTime::Format::Alami::ID;
     my $parser = DateTime::Format::Alami::ID->new();
     my $dt;
     $dt = $parser->parse_datetime("5 jam lagi");
     $dt = $parser->parse_datetime("hari ini");

DESCRIPTION

    This class parses human/natural date/time string and returns DateTime
    object. Currently it supports English and Indonesian. The goal of this
    module is to make it easier to add support for other human languages.

    To actually use this class, you must use one of its subclasses for each
    human language that you want to parse.

    There are already some other DateTime human language parsers on CPAN
    and elsewhere, see "SEE ALSO".

HOW IT WORKS

    DateTime::Format::Alami is base class. Each human language is
    implemented in a separate DateTime::Format::Alami::<ISO_CODE> module
    (e.g. DateTime::Format::Alami::EN and DateTime::Format::Alami::EN)
    which is a subclass.

    Parsing is done using a single recursive regex (i.e. containing
    (?&NAME) and (?(DEFINE)) patterns, see perlre). This regex is composed
    from pieces of pattern strings in the p_* and o_* methods, to make it
    easier to override in an OO-fashion.

    A pattern string that is returned by the p_* method is a normal regex
    pattern string that will be compiled using the /x and /i regex
    modifier. The pattern string can also refer to pattern in other o_* or
    p_* method using syntax <o_foo> or <p_foo>. Example, o_today for
    English might be something like:

     sub p_today { "(?: today | this \s+ day )" }

    Other examples:

     sub p_yesterday { "(?: yesterday )" }
    
     sub p_dateymd { join(
         "",
        '(?: <o_dayint> \\s* ?<o_monthname> | <o_monthname> \\s* <o_dayint>\\b|<o_monthint>[ /-]<o_dayint>\\b )',
        '(?: \\s*[,/-]?\\s* <o_yearint>)?'
     )}
    
     sub o_date { "(?: <p_today>|<p_yesterday>|<p_dateymd>)" }
    
     sub p_time { "(?: <o_hour>:<o_minute>(?:<o_second>)? \s* <o_ampm> )" }
    
     sub p_date_time { "(?: <o_date> (?:\s+ at)? <o_time> )" }

    When a pattern from p_* matches, a corresponding action method a_* will
    be invoked. Usually the method will set or modify a DateTime object in
    $self->{_dt}. For example, this is code for a_today:

     sub a_today {
         my $self = shift;
         $self->{_dt} = DateTime->today;
     }

    The patterns from all p_* methods will be combined in an alternation to
    form the final pattern.

    An o_* pattern is just like p_*, but they will not be combined into the
    final pattern and matching it won't execute a corresponding a_* method.

    And there are also w_* methods which return array of strings.

ADDING A NEW HUMAN LANGUAGE

    TBD

METHODS

 new => obj

    Constructor. You actually must instantiate subclass instead.

 parse_datetime($str[ , \%opts ]) => obj

    Parse/extract date/time expression in $str. Return undef if expression
    cannot be parsed. Otherwise return DateTime object (or string/number if
    format option is verbatim/epoch, or hash if format option is combined)
    or array of objects/strings/numbers (if returns option is
    all/all_cron).

    Known options:

      * time_zone => str

      Will be passed to DateTime constructor.

      * format => str (DateTime|verbatim|epoch|combined)

      The default is DateTime, which will return DateTime object. Other
      choices include verbatim (returns the original text), epoch (returns
      Unix timestamp), combined (returns a hash containing keys like
      DateTime, verbatim, epoch, and other extra information: pos [position
      of pattern in the string], pattern [pattern name], m [raw named
      capture groups], uses_time [whether the date involves time of day]).

      You might think that choosing epoch could avoid the overhead of
      DateTime, but actually you can't since DateTime is used as the
      primary format during parsing. The epoch is retrieved from the
      DateTime object using the epoch method.

      But if you choose verbatim, you can avoid the overhead of DateTime
      (as long as you set returns to first, last, or all).

      * prefers => str (nearest|future|past)

      NOT YET IMPLEMENTED.

      This option decides what happens when an ambiguous date appears in
      the input. For example, "Friday" may refer to any number of Fridays.
      Possible choices are: nearest (prefer the nearest date, the default),
      future (prefer the closest future date), past (prefer the closest
      past date).

      * returns => str (first|last|earliest|latest|all|all_cron)

      If the text has multiple possible dates, then this argument
      determines which date will be returned. Possible choices are: first
      (return the first date found in the string, the default), last
      (return the final date found in the string), earliest (return the
      date found in the string that chronologically precedes any other date
      in the string), latest (return the date found in the string that
      chronologically follows any other date in the string), all (return
      all dates found in the string, in the order they were found in the
      string), all_cron (return all dates found in the string, in
      chronological order).

      When all or all_cron is chosen, function will return array(ref) of
      results instead of a single result, even if there is only a single
      actual result.

FAQ

 What does "alami" mean?

    It is an Indonesian word, meaning "natural".

SEE ALSO

 Similar modules on CPAN

    Date::Extract. DateTime::Format::Alami has some features of
    Date::Extract so it can be used to replace Date::Extract.

    For Indonesian: DateTime::Format::Indonesian, Date::Extract::ID
    (currently this module uses DateTime::Format::Alami as its backend).

    For English: DateTime::Format::Natural. You probably want to use this
    instead, unless you want something other than English. I did try to
    create an Indonesian translation for this module a few years ago, but
    gave up. Perhaps I should make another attempt.

 Other modules on CPAN

    DateTime::Format::Human deals with formatting and not parsing.

 Similar non-Perl libraries

    Natt Java library, which the last time I tried sometimes gives weird
    answer, e.g. "32 Oct" becomes 1 Oct in the far future.
    http://natty.joestelmach.com/

    Duckling Clojure library, which can parse date/time as well as numbers
    with some other units like temperature.
    https://github.com/wit-ai/duckling