minimal parsing of rfc-1123 date-time strings
Parses and prints dates in RFC-1123 format. Like this:
CL-USER> (ql:quickload :trivial-rfc-1123) CL-USER> (t1123:parse-date "Fri, 16 Jul 2010 02:33:50 -0500") ;note 't1132:' abbrev. 3488254430 CL-USER> (t1123:as-rfc-1123 3488254430); default tz is 0, or GMT "Fri, 16-Jul-2010 07:33:50 GMT" CL-USER> (t1123:as-rfc-1123 3488254430 :timezone 5); 'cause lisp TZ is backwards "Fri, 16-Jul-2010 02:33:50 -0500" CL-USER> (t1123:as-rfc-1123 (get-universal-time) :timezone nil); use current tz! ...
Return: universal time for the string.
date-parse-error condition will be raised in case of problems.
(as-rfc-1123 universal-time &key (stream nil) (timezone 0)
- nil return string
- t output to standard-output
- valid stream - output to stream.
- Specify timezone for output. Lisp timezone, please (it is backwards from the normal offset: for GMT-08:00, specify 8). Only rational timezones are supported. Nil means use current tz from (decode-universal-time) which is useful for current time.
Return: string if stream is nil, nil otherwise.
Parts are subject to "Edi Weitz" license, and the entire surrounding project, a similar BSD 3-clause license. The lowdown: credit copyright ownership to Dr. Edward Weitz and Stacksmith, pack licenses and disclaimers with your code and distributables, and do not use the authors' names without permission for any unreasonable purpose.
The code started out in drakma and was shoehorned to be a standalone library for applications requiring minimal date parsing and printing.
According to Drakma authors, the following formats will be parsed:
Wed, 06-Feb-2008 21:01:38 GMT Wed, 06-Feb-08 21:01:38 GMT Tue Feb 13 08:00:00 2007 GMT Wednesday, 07-February-2027 08:55:23 GMT Wed, 07-02-2017 10:34:45 GMT
Note: Drakma is not clear on this, but if a timezone offset is specified, it is always considered to be from GMT. It will accept "PST-02:00", but the result is same as "GMT-02:00", or plain "-02:00".
The following was added to the drakma code, based on empirical studies of NNTP dates:
Fri, 07-02-2017 10:34:45 +0800 numeric timezone is ok - 4 digits HHMM Fri, 07-02-2017 10:34:45 +08:00 colon is ok HH:MM 07-02-2017 10:34:45 GMT omitting day is ok WEd, 06-Feb-08 21:01:38 GmT no longer case sensitive
A limited output function was added. For more flexible output (such as better timezone handling), see local-time - which sadly does not parse RFC-1123, but outputs it.