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Re: [ddlm-group] CIF2 Syntax all wrapped up?

James Hester wrote:
> I would answer as follows:
...
>     2) What are the rules for comments within lists and tables?
> 
> I would treat them as whitespace
One detail is whether the "#" starting a comment requires preceding 
whitespace. Herbert's example is:

    [1,#one
     2, #two
     3 #three
     ,4 #four
     ]

He suggests that preceding whitespace is there only if needed to 
terminate the preceding token, and not a requirement in the actual 
comment syntax. This looks OK in the above example, but may not be clear 
after a quoted string:
    "string"#comment

Or, perhaps this is no less clear than the lack of whitespace in a list:
   ["string"]


>     4) Why require single or double quotes for table index strings, rather
>     than just follow the normal quoting rules?
> 
> 
> No good reason - so let's just follow the normal rules.
> 
Should quotes be requires at all for the index string? Correct parsing 
only requires quotes if the index string contains a colon. In the 
current draft, that is imposed for all strings, not just table-index 
strings. So, there is no need to mandate quotes here, unless the global 
requirement to quote strings with : is dropped.

Maybe the intention was to disallow multi-line index strings?


>     Some of these are more technical details compared to the other issues.
>     These came up while I was working on a big CIF2 regular-expression,
>     where parsing details have to be considered more carefully.
> 
> Actually, it would be rather good if you could post these regular 
> expressions once we have a final specification, as they are likely to be 
> useful to a broad audience.
I plan to do that. To be fully functional, it has to be done in Perl 
syntax, which has a feature that allows recursion for table and list 
values. Despite that caveat, it will be useful even where the full 
recursive expression will not work.

Joe
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