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Re: Parsing of comments in BNC definition

  • Subject: Re: Parsing of comments in BNC definition
  • From: Brian McMahon <bm@xxxxxxxx>
  • Date: Thu, 23 Nov 2000 10:00:36 GMT

This query has by chance arisen simultaneously in another context. My
guidance in such matters is the Star_Base application from Perth. If I
build an example file with your suggested block header (including a possible
value for the possible data item, i.e.
             data_block#53 _a_data_item x
) and run sb -r data_block#53 on the file (a request to Star_Base to return
all content in the nominated data block), I obtain:

sb -r data_block#53 foo.jrh
(i)   Command line request:
(i)   data_block#53
(i)   Input files are :
(i)   foo.jrh
(i)   Input from:
(i)   foo.jrh
(i)   Starting Parser for STAR File.
(i)   End of input.
(i)   Input from:
(i)   /usr/tmp/aaaa19241
(i)   End of input.
_a_data_item            x

So the intention seems pretty clearly NOT to see the # as introducing white
space in this context.

The BNF needs to be carefully revised to accommodate this.


On Thu, Nov 23, 2000 at 09:48:30AM +0000, James Hester wrote:
> Hello people,
> I guess this is probably question to Nick, and forgive me if I've
> overlooked something.
> I'm currently trying to implement a parser using the draft BNC
> definition, but am confused about the parsing of comments.
> To demonstrate, if I have a data block heading
> data_block#53 _a_data_item
> does the production
> <data_heading>          ::= <DATA_> <non_blank_char>+
> suck up the #53 as well (# is listed as a non_blank_char)?  Or does
> <data>     ::= { <wspace>+ <data_name> <wspace>* <blank> <data_value_1> }
> mean that #53... -> comment -> wspace mean that '#53 _a_data_item' can
> be considered as the whitespace before the data name?  This question
> applies in a number of other places as well, where '#' might occur as
> part of a data value.
> I await enlightenment,
> James.
> _______________________________________________________________________
> James Hester, ANBF                             KEK
> e-mail: jrh@anbf2.kek.jp                       Oho 1-1
> ________________________________________________________________________

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