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Re: ABNF switch: list rules

From: Henrik Nordstrom <henrik@henriknordstrom.net>
Date: Sat, 24 May 2008 01:25:43 +0200
To: Julian Reschke <julian.reschke@gmx.de>
Cc: Bjoern Hoehrmann <derhoermi@gmx.net>, HTTP Working Group <ietf-http-wg@w3.org>
Message-Id: <1211585143.30132.32.camel@henriknordstrom.net>
On fre, 2008-05-23 at 15:19 +0200, Julian Reschke wrote:

> The more I look into this, the better the original syntax looks :-)

Yes, there is reasons why HTTP has the list syntax.. and I think that
one does a great job in keeping the BNF readable.

The reasons for the implied LWS is the same, to make the grammar more
readable, but unfortunately that one hasn't worked out very well..

If we can get the BNF syntax to a level of

  ABNF + list syntax, without implied LWS

then a lot is gained.

Eleminating the list syntax is mainly a goal to line up the HTTP BNF
syntax completely with other specifications, but I have a feeling that
it may be better to extend ABNF with a usable list construct.

While we are at that topic. The specification probably should make sure
to recommend producers to not produce lists with empty elements (a
SHOULD NOT). Not sure we have that in the specs today. Parsers MUST
accept them however and is what the BNF description describes but there
quite likely is many broken implementations out there not expecting
empty elements..


Received on Friday, 23 May 2008 23:26:20 UTC

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