package Date::Extract;
use strict;
use warnings;
use DateTime::Format::Natural;
use List::Util 'reduce';
use parent 'Class::Data::Inheritable';
our $VERSION = '0.04';
__PACKAGE__->mk_classdata($_) for qw/scalar_downgrade handlers regex/;
sub _croak {
require Carp;
Carp::croak @_;
}
sub new {
my $class = shift;
my %args = (
returns => 'first',
prefers => 'nearest',
time_zone => 'floating',
@_,
);
if ($args{returns} ne 'first'
&& $args{returns} ne 'last'
&& $args{returns} ne 'earliest'
&& $args{returns} ne 'latest'
&& $args{returns} ne 'all'
&& $args{returns} ne 'all_cron') {
_croak "Invalid `returns` passed to constructor: expected `first', `last', `earliest', `latest', `all', or `all_cron'.";
}
if ($args{prefers} ne 'nearest'
&& $args{prefers} ne 'past'
&& $args{prefers} ne 'future') {
_croak "Invalid `prefers` passed to constructor: expected `nearest', `past', or `future'.";
}
my $self = bless \%args, ref($class) || $class;
return $self;
}
# This method will combine the arguments of parser->new and extract. Modify the
# "to" hash directly.
sub _combine_args {
shift;
my $from = shift;
my $to = shift;
$to->{prefers} ||= $from->{prefers};
$to->{returns} ||= $from->{returns};
$to->{time_zone} ||= $from->{time_zone};
}
sub extract {
my $self = shift;
my $text = shift;
my %args = @_;
# using extract as a class method
$self = $self->new
if !ref($self);
# combine the arguments of parser->new and this
$self->_combine_args($self, \%args);
# when in scalar context, downgrade
$args{returns} = $self->_downgrade($args{returns})
unless wantarray;
# do the work
my @ret = $self->_extract($text, %args);
# munge the output to match the desired return type
return $self->_handle($args{returns}, @ret);
}
# build the giant regex used for parsing. it has to be a single regex, so that
# the order of matches is correct.
sub _build_regex {
my $self = shift;
my $relative = '(?:today|tomorrow|yesterday)';
my $long_weekday = '(?:Monday|Tuesday|Wednesday|Thursday|Friday|Saturday|Sunday)';
my $short_weekday = '(?:Mon|Tue|Wed|Thu|Fri|Sat|Sun)';
my $weekday = "(?:$long_weekday|$short_weekday)";
my $relative_weekday = "(?:(?:next|previous|last)\\s*$weekday)";
my $long_month = '(?:January|February|March|April|May|June|July|August|September|October|November|December)';
my $short_month = '(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)';
my $month = "(?:$long_month|$short_month)";
# 1 - 31
my $cardinal_monthday = "(?:[1-9]|[12][0-9]|3[01])";
my $monthday = "(?:$cardinal_monthday(?:st|nd|rd|th)?)";
my $day_month = "(?:$monthday\\s*$month)";
my $month_day = "(?:$month\\s*$monthday)";
my $day_month_year = "(?:(?:$day_month|$month_day)\\s*,\\s*\\d\\d\\d\\d)";
my $yyyymmdd = "(?:\\d\\d\\d\\d[-/]\\d\\d[-/]\\d\\d)";
my $ddmmyy = "(?:\\d\\d[-/]\\d\\d[-/]\\d\\d)";
my $ddmmyyyy = "(?:\\d\\d[-/]\\d\\d[-/]\\d\\d\\d\\d)";
my $other = $self->_build_more_regex;
$other = "|$other"
if $other;
my $regex = qr{
\b(
$relative # today
| $relative_weekday # last Friday
| $weekday # Monday
| $day_month_year # November 13th, 1986
| $day_month # November 13th
| $month_day # 13 Nov
| $yyyymmdd # 1986/11/13
| $ddmmyy # 11-13-86
| $ddmmyyyy # 11-13-1986
$other # anything from the subclass
)\b
}ix;
$self->regex($regex);
}
# this is to be used in subclasses for adding more stuff to the regex
# for example, to add support for $foo_bar and $baz_quux, return
# "$foo_bar|$baz_quux"
sub _build_more_regex { '' }
# build the list->scalar downgrade types
sub _build_scalar_downgrade {
my $self = shift;
$self->scalar_downgrade({
all => 'first',
all_cron => 'earliest',
});
}
# build the handlers that munge the list of dates to the desired order
sub _build_handlers {
my $self = shift;
$self->handlers({
all_cron => sub {
sort { DateTime->compare_ignore_floating($a, $b) } @_
},
all => sub { @_ },
earliest => sub { reduce { $a < $b ? $a : $b } @_ },
latest => sub { reduce { $a > $b ? $a : $b } @_ },
first => sub { $_[0] },
last => sub { $_[-1] },
});
}
# actually perform the scalar downgrade
sub _downgrade {
my $self = shift;
my $returns = shift;
my $downgrades = $self->scalar_downgrade || $self->_build_scalar_downgrade;
return $downgrades->{$returns} || $returns;
}
sub _handle {
my $self = shift;
my $returns = shift;
my $handlers = $self->handlers || $self->_build_handlers;
my $handler = $handlers->{$returns};
return defined $handler ? $handler->(@_) : @_
}
sub _extract {
my $self = shift;
my $text = shift;
my %args = @_;
my $regex = $self->regex || $self->_build_regex;
my @gleaned = $text =~ /$regex/g;
my %dtfn_args;
$dtfn_args{prefer_future} = 1
if $args{prefers} && $args{prefers} eq 'future';
$dtfn_args{time_zone} = $args{time_zone};
my $parser = DateTime::Format::Natural->new(%dtfn_args);
my @ret;
for (@gleaned) {
my $dt = $parser->parse_datetime($_);
push @ret, $dt->set_time_zone($args{time_zone})
if $parser->success;
}
return @ret;
}
1;
__END__
=head1 NAME
Date::Extract - extract probable dates from strings
=head1 SYNOPSIS
my $parser = Date::Extract->new();
my $dt = $parser->extract($arbitrary_text)
or die "No date found.";
return $dt->ymd;
=head1 MOTIVATION
There are already a few modules for getting a date out of a string.
L<DateTime::Format::Natural> should be your first choice. There's also
L<Time::ParseDate> which fits many formats. Finally, you can coerce
L<Date::Manip> to do your bidding.
But I needed something that will take an arbitrary block of text, search it
for something that looks like a date string, and build a L<DateTime> object
out of it. This module fills this niche. By design it will produce few false
positives. This means it will not catch nearly everything that looks like a
date string. So if you have the string "do homework for class 2019" it won't
return a L<DateTime> object with the year set to 2019. This is what your users
would probably expect.
=head1 METHODS
=head2 new PARAMHASH => C<Date::Extract>
=head3 arguments
=over 4
=item time_zone
Forces a particular time zone to be set (this actually matters, as "tomorrow"
on Monday at 11 PM means something different than "tomorrow" on Tuesday at 1
AM).
By default it will use the "floating" time zone. See the documentation for
L<DateTime>.
This controls both the input time zone and output time zone.
=item prefers
This argument decides what happens when an ambiguous date appears in the
input. For example, "Friday" may refer to any number of Fridays. The valid
options for this argument are:
=over 4
=item nearest
Prefer the nearest date. This is the default.
=item future
Prefer the closest future date.
=item past
Prefer the closest past date. B<NOT YET SUPPORTED>.
=back
=item returns
If the text has multiple possible dates, then this argument determines which
date will be returned. By default it's 'first'.
=over 4
=item first
Returns the first date found in the string.
=item last
Returns the final date found in the string.
=item earliest
Returns the date found in the string that chronologically precedes any other
date in the string.
=item latest
Returns the date found in the string that chronologically follows any other
date in the string.
=item all
Returns all dates found in the string, in the order they were found in the
string.
=item all_cron
Returns all dates found in the string, in chronological order.
=back
=back
=head2 extract text, ARGS => C<DateTime>s
Takes an arbitrary amount of text and extracts one or more dates from it. The
return value will be zero or more C<DateTime> objects. If called in scalar
context, only one will be returned, even if the C<returns> argument specifies
multiple possible return values.
See the documentation of C<new> for the configuration of this method. Any
arguments passed into this method will trump those from the constructor.
You may reuse a parser for multiple calls to C<extract>.
You do not need to have an instantiated C<Date::Extract> object to call this
method. Just C<< Date::Extract->extract($foo) >> will work.
=head1 FORMATS HANDLED
=over 4
=item * today; tomorrow; yesterday
=item * last Friday; next Monday; previous Sat
=item * Monday; Mon
=item * November 13th, 1986; Nov 13, 1986
=item * November 13th; Nov 13
=item * 13 Nov; 13th November
=item * 1986/11/13; 1986-11-13
=item * 11-13-86; 11/13/1986
=back
=head1 CAVEATS
This module is I<intentionally> very simple. Surprises are I<not> welcome
here.
=head1 SEE ALSO
L<DateTime::Format::Natural>, L<Time::ParseDate>, L<Date::Manip>
=head1 AUTHOR
Shawn M Moore, C<< <sartak at bestpractical dot com> >>
=head1 ACKNOWLEDGEMENTS
Thanks to Steven Schubiger for writing the fine L<DateTime::Format::Natural>.
We still use it, but it doesn't quite fill all the particular needs we have.
=head1 COPYRIGHT & LICENSE
Copyright 2007-2009 Best Practical Solutions.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
=cut