Re: [ddlm-group] Characterset of non-delimited strings insidecompound data items. .
- To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
- Subject: Re: [ddlm-group] Characterset of non-delimited strings insidecompound data items. .
- From: SIMON WESTRIP <simonwestrip@btinternet.com>
- Date: Tue, 9 Nov 2010 18:06:52 +0000 (GMT)
- In-Reply-To: <8F77913624F7524AACD2A92EAF3BFA5416659DEE46@SJMEMXMBS11.stjude.sjcrh.local>
- References: <AANLkTimVXn5ZEEBZx37YtgjP3g8AdZGZEise7fF=C+Ee@mail.gmail.com><alpine.BSF.2.00.1011082115550.70856@epsilon.pair.com><AANLkTikbuR2aCebXKsq_smzUhbijLWN7CrPttBQ0urLV@mail.gmail.com><370271.52057.qm@web87009.mail.ird.yahoo.com><8F77913624F7524AACD2A92EAF3BFA5416659DEE46@SJMEMXMBS11.stjude.sjcrh.local>
should be separated from a preceding/subsequent value (or 'parent' value) by whitespace. Afterall, the brackets delimit a *value*, even if that value is made up of other
values? To me this seems quite logical (and actually allows a fairly simple description of the syntax at a lexical level in terms of delimited and non-delimited
'strings' separated by whitespace), but I suspect this will not be received favourably :-)
Cheers
Simon
From: "Bollinger, John C" <John.Bollinger@STJUDE.ORG>
To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
Sent: Tuesday, 9 November, 2010 15:35:07
Subject: Re: [ddlm-group] Characterset of non-delimited strings insidecompou nd data items. .
I would be fine with disallowing all of [, ], {, and } from appearing anywhere in a whitespace-delimited data value. The [ and { do not at present cause lexical ambiguity, but there’s something to be said for consistent treatment of opening and closing delimiters. Do note, however, that the opening [ of a list or { of a table is still required to be separated from any preceding value by whitespace. Thus
_t [ depth_1[depth_1_still ] ]
would contain an error at the second [. (There is still an error under the current spec or if only ] and } are forbidden in whitespace-delimited data values, but it is at the final ].) This is still OK, though:
_t [[depth_2] depth_1]
John
From: ddlm-group-bounces@iucr.org [mailto:ddlm-group-bounces@iucr.org]
On Behalf Of SIMON WESTRIP
Sent: Tuesday, November 09, 2010 9:03 AM
To: Group finalising DDLm and associated dictionaries
Subject: Re: [ddlm-group] Characterset of non-delimited strings insidecompou nd data items. .
I would suggest adding [ & { also:
_t [ depth_1[depth_1_still [ depth_2 x=a1[a2[a3[a4[i]]]];]]
?
Simon
From: James Hester <jamesrhester@gmail.com>
To: Group finalising DDLm and associated dictionaries <ddlm-group@iucr.org>
Sent: Tuesday, 9 November, 2010 3:14:55
Subject: Re: [ddlm-group] Characterset of non-delimited strings inside compound data items
Indeed. I agree that "ease of use of flex" is not a good criterion. A
better way of putting it would be "simplicity of implementation".
Glad you don't object to excluding close brackets.
James.
On Tue, Nov 9, 2010 at 1:23 PM, Herbert J. Bernstein
<yaya@bernstein-plus-sons.com> wrote:
> While I have no particular objection to excluding the close brackets from
> non-delimited strings, personally I think making easy use of flex a
> criterion for the design of CIF2 is not a good idea. -- Herbert
> =====================================================
> Herbert J. Bernstein, Professor of Computer Science
> Dowling College, Kramer Science Center, KSC 121
> Idle Hour Blvd, Oakdale, NY, 11769
>
> +1-631-244-3035
> yaya@dowling.edu
> =====================================================
>
> On Tue, 9 Nov 2010, James Hester wrote:
>
>> Dear DDLm group,
>>
>> John Bollinger has alerted me to a glitch in the current DDLm
>> specification, to wit: (i) close bracket characters are allowed as
>> non-final characters in a non-delimited string, and (ii) there is no
>> requirement for whitespace between a datavalue and the close bracket
>> symbol that denotes the end of a table or list value.
>>
>> This means that, in order to decide whether a close bracket character
>> terminates a list or is just another character in the non-delimited
>> string, the parser must look ahead, potentially many levels of
>> nesting. For example:
>>
>> _t [outer [inner1 inner2]]
>>
>>
>> The parser does not know that the first close bracket closes the inner
>> list until it has read past the second close bracket. Or even more
>> confusingly:
>>
>> _t [ depth_1 [ depth_2 [ depth_3 x=a1[a2[a3[a4[i]]]];]]]
>>
>>
>> While this behaviour is not intractable, it is also not possible to
>> use simple lexing tools (e.g. flex) to handle such syntax. I would
>> therefore like to propose the following change to the current draft
>> specification:
>>
>> "The characters ']' and '}' may not appear anywhere in a non-delimited
>> datavalue"
>>
>> James.
>> --
>> T +61 (02) 9717 9907
>> F +61 (02) 9717 3145
>> M +61 (04) 0249 4148
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>>
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--
T +61 (02) 9717 9907
F +61 (02) 9717 3145
M +61 (04) 0249 4148
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