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Re: [ddlm-group] New syntax: 'marker' characters

Hi Joe and others: based on what Joe reports, it would seem pointless
to add markers to the syntax, as an application can simply do a first
quick non-tokenising run through a CIF file and create an index for
itself if it desires efficient data extraction.

I'll take up the theme of ordering elsewhere.

James.

On Thu, Nov 5, 2009 at 5:53 AM, Joe Krahn <krahn@niehs.nih.gov> wrote:

> I use a regexp that properly handles all comments and quoting types in
> CIF1, so it does not just search for the 'data_' sub-string.
>
> I am actually surprised that it could parse so quickly. However, this
> requires parsing characters without tokenizing them; a data block is a
> single regexp. A normal CIF parser may not be designed to parse without
> tokenizing and storing values, so it may take some redesign to get the
> same performance even in a compiled program.
>
> Of course, there is no reason why a given CIF implementation could not
> use comments as hints for faster parsing. Even with the above argument
> that fast parsing is possible, a large network-mounted file could go
> slow just reading the intervening file data. However, putting the hints
> in comments means that it does not need to be part of the CIF spec.
>
> Ordering hints are a bit different, because they affect more than just
> comments. Currently, order is supposed to be irrelevant, so you could
> claim that it is also just a performance hint. I have always thought
> that a canonical order is useful. Most CIF software writes out "pretty"
> formatted text because organization is useful when being viewed by a
> human. Herbert's suggestion is to make preferred ordering an integral
> part of the DDL, but avoid incorporating ordering rules into the CIF
> syntax. Then, people that want ordering rules can use them, but it avoid
> complicating the CIF spec.
>
> Joe Krahn
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>



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