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Re: Media Fragments URI parsing: pseudo algorithm code

From: Jack Jansen <Jack.Jansen@cwi.nl>
Date: Wed, 7 Jul 2010 09:31:27 +0200
Cc: "Bjoern Hoehrmann" <derhoermi@gmx.net>, public-media-fragment@w3.org
Message-Id: <2054D49A-6FBE-4A6F-BB44-21A63F973095@cwi.nl>
To: Philip Jägenstedt <philipj@opera.com>

On 6 jul 2010, at 16:35, Philip Jägenstedt wrote:
> However, given this situation, how is it possible to express parsing in a single layer of ABNF? When the ABNF says "t", it really means "t" or "%74", if these are indeed supposed to be equivalent. How do other specs layered on top of URI handle this?


I think the single layer is the issue here. The whole idea that permeates this thread, that a single ABNF should capture not only grammar but also semantics and even future expansion, is causing no end to trouble. This is where you need layering, with percent-escaping in its own layer. And extensibility and semantics also not in the grammar ABNF.

Imaging how ugly things would be if K&R had tried to capture the C preprocessor instructions in the C language syntax. Even though CPP is always there and an integral part of the language trying to capture it in the ASN would be ridiculous.
--
Jack Jansen, <Jack.Jansen@cwi.nl>, http://www.cwi.nl/~jack
If I can't dance I don't want to be part of your revolution -- Emma Goldman
Received on Wednesday, 7 July 2010 07:49:51 GMT

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