Re: [yang-doctors] canonical order question

[Martin Björklund <[e-mail]>]

Scott Mansfield <[e-mail]> wrote:
> Thanks for the context, however I'm talking about body-stmts.

I know, please see my reply:

  But for body-stmts, the ABNF allows any order of the child
  statements.  Hence the canonical order also allows any order.


[Note that *(A / B) means any number of A or B in any order]


/martin




> 
> Can body-stmts can be in any order? I don't see anywhere where the ABNF says body-stmts can be in any order.  I see what you mean for import-stmts and linkage-stmts, but those aren't the statements I'm concerned about in my example.
> 
> I had the following..
> module {
> ...
>    import {
>    }
>    feature {
>    }
>    augment {
>    }
>    notification {
>    }
> }
> 
> That was changed by the --yang-canonical flag to: (notifications were moved above the augment)
> module {
> ...
>    import {
>    }
>    feature {
>    }
>    notification {
>    }
>    augment {
>    }
> }
> 
> augment-stmt and notification-stmt are body-stmts.  So I assumed the order in the ABNF in the body-stmts list was the canonical order.  But that is not what pyang --yang-canonical does.
> 
> Regards,
> -scott.
>    
> 
> -----Original Message-----
> From: Martin Björklund <[e-mail]> 
> Sent: Wednesday, November 22, 2023 5:29 AM
> To: Scott Mansfield <[e-mail]>
> Cc: [e-mail]
> Subject: Re: [yang-doctors] canonical order question
> 
> Hi,
> 
> Scott Mansfield <scott.mansfield=[e-mail]> wrote:
> > I looked through the mail archive and the pyang issues list on git, so 
> > apologies if I missed this...
> > 
> > However,
> > 
> > Clause 14 of RFC 7950 says this...
> >    body-stmts          = *(extension-stmt /
> >                            feature-stmt /
> >                            identity-stmt /
> >                            typedef-stmt /
> >                            grouping-stmt /
> >                            data-def-stmt /
> >                            augment-stmt /
> >                            rpc-stmt /
> >                            notification-stmt /
> >                            deviation-stmt)
> > 
> > 
> > But when I use pyang and the -yang-canonical switch, the output I get 
> > has the notification statements before the augment statements.  Is 
> > this ok?  Am I reading the ABNF incorrectly?
> 
> RFC 7950 says:
> 
>    The ABNF grammar
>    [RFC5234] [RFC7405] defines the canonical order.
> 
> And then the grammar has for example:
> 
>    linkage-stmts       = ;; these stmts can appear in any order
>                          *import-stmt
>                          *include-stmt
> 
> So, the ABNF says that "import" comes before "include" which means that this is the canonical order.
> 
> But for body-stmts, the ABNF allows any order of the child statements.  Hence the canonical order also allows any order.
> 
> 
> /martin
> 
> 
> 
> 
> > 
> > I have attached the before and after for information.
> > ieee802-dot1q-rstp.yang is the original which has notifications after 
> > the augment statement.  I then ran it though pyang with -f yang 
> > -yang-canonical and put the result in ieee802-dot1q-rstp-canon.yang, 
> > but now the notification statements were moved before the augment.
> > Just trying to understand what the canonical order is.
> > 
> > Many thanks for the help and experience!
> > Regards,
> > -scott.
> > 
> > 
> > 
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