ietf-nntp Detailed syntax

[Clive D.W. Feather]

Paul Overell said:
>> Alternatively, since this sequence is only used for command ends and all
>> commands end that way, make the root productions:
>>        command-line = command *WSP CRLF
> Or use
>           command-line = command [WSP] CRLF
> 
> Which I think is clearer and also gives an unambiguous parse (not that 
> that is important here)

Yes, that's better. My silly.

>> Finally, though I haven't done it here, I think that alphabetical order
>> isn't the best choice.

> Having spend many frustrating hours over the years searching for 
> particular productions in non-alphabetical syntaxes - I strongly 
> disagree.

Well, I'll agree to disagree then. This isn't an issue people need to spend
their time on, so I'll leave it in Stan's hands.

> Syntax is not read as prose from top to bottom but by production, so 
> being able to quickly find a particular production is important.

I think Algol 68 did it best. Every syntax rule had a letter (and no clause
had more than 26 syntax rules). Tokens on the right side had a
cross-reference to where they were defined while those on the left had
cross-references to all the places they were used (unless they were too
common). So you'd see something like:

    a) command-line {22dg,412k} = command {b} [WSP] CRLF
    b) command {a} = word {46c} WSP word

etc, where command-line is used in 2.2 rules d and g and 4.1.2 rule k,
while word is defined in 4.6 rule c.

-- 
Clive D.W. Feather  | Work:  <clive at demon.net>   | Tel:  +44 20 8371 1138
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