Re: regular expression syntax checker

On 6/27/04 10:15 PM, "Joe Savelberg" <joe@xxxxxxxxxxx> wrote:

> I just came across this interesting regular expression syntax
> checker. This might come in handy when creating new filters in
> Post.Office or SpamAssassin.
> http://www.bitesizeinc.net/demo.regexp.html

Don't try to check your regexp for PO filters against this engine! PO regexp
is NOT regexp, I repeat PO regexp is NOT regexp.

PO gives you some regexp and some globbing mixed up into one. It makes
filters using regexp pretty much useless and the syntax is custom to PO so
you can't test other than by trial and error. It is possible to change the
regexp handling by switching an ENV var, however, if you are into that sort
of thing. Talk to texh support for info on that one. I personally think
writing custom regexp in SpamAssassin is a better approach - though I
haven't done that yet.

How Post.Office SMTP filters modify regexp strings:
___________________________________________________
1) star (*) transformed to dot star (.*) anywhere in user-submitted
string/pattern - can't do 0 or more pattern repetition

2) header name string prepended to user-submitted string/pattern - can't
construct regexp without 'Headername:' string prepended

3) caret (^) prepended to header name - forces regexp to match start of line

4) dollarsign ($) appended to end of string/pattern - forces regexp to match
end of line

5) character classes disabled (true?) or straight brackets not properly
handled - can't use shorthand for pre-defined ranges, can't use collating
sequences

6) dot changed to backslash backslash dot - can't specify 'any character'
discreetly

7) single backslash (\) changed to double backslash (\\) - can't use
backreferences

8) Typing "Received:" into the header field has no effect - cannot use SMTP
filters to parse Received: header.
___________________________________________________

Cheers,
dan

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