Provided by: libregexp-common-time-perl_0.14-1_all 
NAME
Regexp::Common::time - Date and time regexps.
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.
• If you know the exact format of the data to be matched, use one of the specific,
piecemeal pattern builders: "tf" or "strftime".
• If you are parsing RFC-2822 mail headers, use the "mail" pattern.
• If you are parsing informal American dates, use the "american" pattern.
• If there is some variability in your input data, use one of the fuzzy-matching
patterns in the "dmy", "mdy", or "ymd" families.
• If the data are wildly variable, such as raw user input, you should probably give up
and use Date::Manip or Date::Parse.
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:
• The date separator character may be a hyphen, slash ("/"), period, or empty string
(omitted). The two date separators must match.
• The time separator character may be a colon, a period, a space, or empty string
(omitted). The two time separators must match.
• The date-time separator may be a "T", an underscore, a space, or empty string
(omitted).
• Either the date or the time may be omitted. But at least one must be there.
• If the date is not omitted, all three of its components must be present.
• If the time is not omitted, all three of its components must be present.
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:
• The pattern names consist of the letters "y", "m", and "d", each optionally followed
by a digit (2 for "m" and "d"; 2 or 4 for "y").
• If a "y" is followed by a 2 or a 4, it must match that many digits.
• If a "y" has no trailing digit, it can match either 2 or 4 digits, trying 4 first.
• If an "m" is followed by a 2, then only two-digit matches for the month are
considered, and month names are not matched.
• If an "m" is not followed by a 2, then the month may be 1 or 2 digits, or a spelled-
out name.
• Just like for months, if a "d" is followed by a 2, then only two-digit matches for the
day are considered.
• Just like for months, if a "d" has no trailing digit, then the day may be 1 or 2
digits, and a 1-digit match may not have any adjacent digits.
• The uppercase "DMY", "MDY", and "YMD" patterns are synonyms for the strict "d2m2y4",
"m2d2y4", and "y4m2d2" patterns, respectively.
• If a one-digit match is considered for the month, then no adjacent digits are allowed.
(e.g.: "1/23/45" in M/D/Y format has a valid one-digit month match, but "12345" does
not. Nor does "91/23/45").
• If a pattern begins with an digitless "d", "m", or "y", then, in the string to be
matched, any leading digits will cause the pattern to fail. For example: "012/23/45"
will not match $RE{time}{mdy}. However, it will match $RE{time}{m2d2y2}. If you
specify an exact pattern by using "m2" instead of "m", this module assumes you know
what you're doing.
• Likewise, a pattern ending with a digitless "d" or "y" will not match if there are
trailing digits in the string.
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
Eric J. Roode, ROODE -at- cpan -dot- org
LICENSE AND 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.