Eric J. Roode > Regexp-Common-time-0.04 > Regexp::Common::time

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Module Version: 0.04   Source   Latest Release: Regexp-Common-time-0.07

NAME ^

Regexp::Common::time - Date and time regexps.

VERSION ^

This is version 0.04 of Regexp::Common::time, May 29, 2008.

SYNOPSIS ^

 use Regexp::Common qw(time);

 # Piecemeal, Time::Format-like patterns
 $RE{time}{tf}{-pat => 'pattern'}

 # Piecemeal, strftime-like patterns
 $RE{time}{strftime}{-pat => 'pattern'}

 # Match ISO8601-style date/time strings
 $RE{time}{iso}

 # Match RFC2822-style date/time strings
 $RE{time}{mail}
 $RE{time}{MAIL}    # more-strict matching

 # Match informal American date strings
 $RE{time}{american}

 # Fuzzy date patterns
 #               YEAR/MONTH/DAY
 $RE{time}{ymd}         # Most flexible
 $RE{time}{YMD}         # Strictest (equivalent to y4m2d2)
                 # Other available patterns: y2md, y4md, y2m2d2, y4m2d2

 #               MONTH/DAY/YEAR  (American style)
 $RE{time}{mdy}         # Most flexible
 $RE{time}{MDY}         # Strictest (equivalent to m2d2y4)
                 # Other available patterns: mdy2, mdy4, m2d2y2, m2d2y4

 #               DAY/MONTH/YEAR  (European style)
 $RE{time}{mdy}         # Most flexible
 $RE{time}{MDY}         # Strictest (equivalent to d2m2y4)
                 # Other available patterns: dmy2, dmy4, d2m2y2, d2m2y4

 # Fuzzy time pattern
 #               HOUR/MINUTE/SECOND
 $RE{time}{hms}    # H: matches 1 or 2 digits; 12 or 24 hours
                   # M: matches 2 digits.
                   # S: matches 2 digits; may be omitted
                   # May be followed by "a", "am", "p.m.", etc.

DESCRIPTION ^

This module creates regular expressions that can be used for parsing dates and times. See Regexp::Common for a general description of how to use this interface.

Parsing dates is a dirty business. Dates are generally specified in one of three possible orders: year/month/day, month/day/year, or day/month/year. Years can be specified with four digits or with two digits (with assumptions made about the century). Months can be specified as one digit, two digits, as a spelled-out name, or as a three-letter abbreviation. Day numbers can be one digit or two digits, with limits depending on the month (and, in the case of February, even the year). Also, different people use different punctuation for separating the various elements.

A human can easily recognize that "October 21, 2005" and "21.10.05" refer to the same date, but it's tricky to get a program to come to the same conclusion. This module attempts to make it possible to do so, with a minimum of difficulty.

Time values are generally much simpler to parse than date values. Only one fuzzy pattern is provided, and it should suffice for most needs.

Time::Format PATTERNS ^

The Time::Format module uses simple, intuitive strings for specifying date and time formats. You can use these patterns here as well. See Time::Format for details about its format specifiers.

Example:

    $str = 'Thu November 2, 2005';
    $str =~ $RE{time}{tf}{-pat => 'Day Month d, yyyy'};

The patterns can contain more complex regexp expressions as well:

    $str =~ $RE{time}{tf}{-pat => '(Weekday|Day) (Month|Mon) d, yyyy'};

Time zone matching (the tz format code) attempts to adhere to RFC2822 and ISO8601 as much as possible. The following time zones are matched:

    Z
    UT        UTC
    +hh:mm    -hh:mm
    +hhmm     -hhmm
    +hh       -hh
    GMT   EST EDT   CST CDT   MST MDT   PST PDT

strftime PATTERNS ^

The POSIX strftime function is a long-recognized standard for formatting dates and times. This module supports most of stftime's codes for matching; specifically, the aAbBcCDdeHIjmMnprRSTtuUVwWyxXYZ% codes. The %Z format matches time zones in the same manner as described above under "Time::Format PATTERNS".

Also, this module provides the following nonstandard codes:

%_d - 1- or 2-digit day number (1-31)

%_H - 1- or 2-digit hour (0-23)

%_I - 1- or 2-digit hour (1-12)

%_m - 1- or 2-digit month number (1-12)

%_M - 1- or 2-digit minute (0-59)

Example:

    $str = 'Thu November 2, 2005';
    $str =~ $RE{time}{strftime}{-pat => '%a %B %_d, %Y'};

The patterns can contain more complex regexp expressions as well:

    $str =~ $RE{time}{strftime}{-pat => '(%A|%a)? (%B|%b) ?%_d, %Y'};

ISO-8601 DATE/TIME MATCHING ^

The $RE{time}{iso} pattern will match most (all?) strings formatted as recommended by ISO-8601. The canonical ISO-8601 form is:

    YYYY-MM-DDTHH:MM:SS

(where "T" is a literal T character). The $RE{time}{iso} pattern will match this form, and some variants:

RFC 2822 MATCHING ^

RFC 2822 specifies the format of date/time values in e-mail message headers. In a nutshell, the format is:

    dd Mon yyyy hh:mm:ss +zzzz

where dd is the day of the month; Mon is the abbreviated month name (apparently always in English); yyyy is the year; hh:mm:ss is the time; and +zzzz is the time zone, generally specified as an offset from GMT.

RFC 2822 requires that the weekday also be specified, but this module ignores the weekday, as it is redundant and only supplied for human readability.

RFC 2822 requires that older, obsolete date forms be allowed as well; for example, alphanumeric time zone codes (e.g. EDT). This module's mail allows for these obsolete date forms. If you want to match only the proper date forms recommended by RFC 2822, you can use the MAIL pattern instead.

In either case, mail or MAIL, the pattern generated is very flexible about whitespace. The main differences are: with MAIL, two-digit years are not permitted, and the time zone must be four digits preceded by a + or - sign.

INFORMAL AMERICAN MATCHING ^

People in North America, particularly in the United States, are fond of specifying dates as "Month dd, yyyy", or sometimes with a two-digit year and apostrophe: "Month dd, 'yy". The american pattern matches this style of date. It allows either a month name or abbreviation, and is flexible with respect to commas and whitespace.

FUZZY PATTERN OVERVIEW ^

Fuzzy date patterns have the following properties in common:

FUZZY PATTERN DETAILS ^

Year-Month-Day order

$RE{time}{ymd}
 "05/4/2"      =~ $RE{time}{ymd};
 "2005-APR-02" =~ $RE{time}{ymd};

This is the most flexible of the numeric-only year/month/day formats. It matches a date of the form "year/month/day", where the year may be 2 or 4 digits; the month may be 1 or 2 digits or a spelled-out name or name abbreviation, and the day may be 1 or 2 digits. The year/month/day elements may be directly adjacent to each other, or may be separated by a space, period, slash (/), or hyphen.

$RE{time}{y4md}
 "2005/4/2"    =~ $RE{time}{y4md};
 "2005 APR 02" =~ $RE{time}{y4md};

This works as $RE{time}{ymd}, except that the year is restricted to be exactly 4 digits.

$RE{time}{y4m2d2}
 "2005/04/02" =~ $RE{time}{y4m2d2};

This works as $RE{time}{ymd}, except that the year is restricted to be exactly 4 digits, and the month and day must be exactly 2 digits each.

$RE{time}{y2md}
 "05/4/2"    =~ $RE{time}{y2md};
 "05.APR.02" =~ $RE{time}{y2md};

This works as $RE{time}{ymd}, except that the year is restricted to be exactly 2 digits.

$RE{time}{y2m2d2}
 "05/04/02" =~ $RE{time}{y2m2d2};

This works as $RE{time}{ymd}, except that the year is restricted to be exactly 2 digits, and the month and day must be exactly 2 digits each.

$RE{time}{YMD}
 "2005/04/02" =~ $RE{time}{YMD};

This is a shorthand for the "canonical" year/month/day format, y4m2d2.

Month-Day-Year (American) order

$RE{time}{mdy}
$RE{time}{mdy4}
$RE{time}{m2d2y4}
$RE{time}{mdy2}
$RE{time}{m2d2y2}
$RE{time}{MDY}

These patterns function as the equivalent year/month/day patterns, above; the only difference is the order of the elements. MDY is a synonym for m2d2y4.

Day-Month-Year (European) order

$RE{time}{dmy}
$RE{time}{dmy4}
$RE{time}{d2m2y4}
$RE{time}{dmy2}
$RE{time}{d2m2y2}
$RE{time}{DMY}

These patterns function as the equivalent year/month/day patterns, above; the only difference is the order of the elements. DMY is a synonym for d2m2y4.

Time pattern (Hour-minute-second) ^

$RE{time}{hms}
 "10:06:12a" =~ /$RE{time}{hms}/;
 "9:00 p.m." =~ /$RE{time}{hms}/;

Matches a time value in a string.

The hour must be in the range 0 to 24. The minute and second values must be in the range 0 to 59, and must be two digits (i.e., they must have leading zeroes if less than 10).

The hour, minute, and second components may be separated by colons (:), periods, or spaces.

The "seconds" value may be omitted.

The time may be followed by an "am/pm" indicator; that is, one of the following values:

  a   am   a.m.  p   pm   p.m.   A   AM   A.M.  P   PM   P.M.

There may be a space between the time and the am/pm indicator.

CAPTURES (-keep) ^

Under -keep, the tf and strftime patterns capture the entire match as $1, plus one capture variable for each format specifier. However, if your pattern contains any parentheses, tf and strftime will not capture anything additional beyond what you specify, -keep or not. In other words: if you use parentheses, you are responsible for all capturing.

The iso pattern captures:

$1 - the entire match

$2 - the year

$3 - the month

$4 - the day

$5 - the hour

$6 - the minute

$7 - the second

The year, month, and day ($2, $3, and $4) will be undef if the matched string contains only a time value (e.g., "12:34:56"). The hour, minute, and second ($5, $6, and $7) will be undef if the matched string contains only a date value (e.g., "2005-01-23").

The mail and MAIL patterns capture:

$1 - the entire match

$2 - the day

$3 - the month

$4 - the year

$5 - the hour

$6 - the minute

$7 - the second

$8 - the time zone

The american pattern captures:

$1 - the entire match

$2 - the month

$3 - the day

$4 - the year

The fuzzy y/m/d patterns capture

$1 - the entire match

$2 - the year

$3 - the month

$4 - the day

The fuzzy m/d/y patterns capture

$1 - the entire match

$2 - the month

$3 - the day

$4 - the year

The fuzzy d/m/y patterns capture

$1 - the entire match

$2 - the day

$3 - the month

$4 - the year

The fuzzy h/m/s pattern captures

$1 - the entire match

$2 - the hour

$3 - the minute

$4 - the second (undef if omitted)

$5 - the am/pm indicator (undef if omitted)

EXAMPLES ^

 # Typical usage: parsing a data record.
 #
 $rec = "blah blah 2005/10/21 blah blarrrrrgh";
 @date = $rec =~ m{^blah blah $RE{time}{YMD}{-keep}};
 # or
 @date = $rec =~ m{^blah blah $RE{time}{tf}{-pat=>'yyyy/mm/dd'}{-keep}};
 # or
 @date = $rec =~ m{^blah blah $RE{time}{strftime}{-pat=>'%Y/%m/%d'}{-keep}};

 # Typical usage: parsing variable-format data.
 #
 use Time::Normalize;

 $record = "10-SEP-2005";

 # This block tries M-D-Y first, then D-M-Y, then Y-M-D
 my $matched;
 foreach my $pattern (qw(mdy dmy ymd))
 {
     @values = $record =~ /^$RE{time}{$pattern}{-keep}/
         or next;

     $matched = $pattern;
 }
 if ($matched)
 {
     eval{ ($year, $month, $day) = normalize_rct($matched, @values) };
     if ($@)
     {
         .... # handle erroneous data
     }
 }
 else
 {
     .... # no match
 }
 #
 # $day is now 10; $month is now 09; $year is now 2005.


 # Time examples

 $time = '9:10pm';

 @time_data = $time =~ /$RE{time}{hms}{-keep}/;
 # captures '9:10pm', '9', '10', undef, 'pm'

 @time_data = $time =~ /$RE{time}{tf}{-pat => '(h):(mm)(:ss)?(am)?'}{-keep}/;
 # captures '9', '10', undef, 'pm'

EXPORTS ^

This module exports no symbols to the caller's namespace.

SEE ALSO ^

It's not enough that the date regexps can match various formats. You then have to parse those matched data values and translate them into useful values. The Time::Normalize module is highly recommended for performing this repetitive, error-prone task.

REQUIREMENTS ^

Requires Regexp::Common, of course.

If POSIX and I18N::Langinfo are available, this module will use them; otherwise, it will use hardcoded English values for month and weekday names.

Test::More is required for the test suite.

AUTHOR / COPYRIGHT ^

Copyright (c) 2005-2008 by Eric J. Roode, ROODE -at- cpan -dot- org

All rights reserved.

To avoid my spam filter, please include "Perl", "module", or this module's name in the message's subject line, and/or GPG-sign your message.

This module is copyrighted only to ensure proper attribution of authorship and to ensure that it remains available to all. This module is free, open-source software. This module may be freely used for any purpose, commercial, public, or private, provided that proper credit is given, and that no more-restrictive license is applied to derivative (not dependent) works.

Substantial efforts have been made to ensure that this software meets high quality standards; however, no guarantee can be made that there are no undiscovered bugs, and no warranty is made as to suitability to any given use, including merchantability. Should this module cause your house to burn down, your dog to collapse, your heart-lung machine to fail, your spouse to desert you, or George Bush to be re-elected, I can offer only my sincere sympathy and apologies, and promise to endeavor to improve the software.

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