Re: XPATH evaluation - Mailing list pgsql-hackers

From Radosław Smogura
Subject Re: XPATH evaluation
Date
Msg-id 201106181851.26516.rsmogura@softperience.eu
Whole thread Raw
In response to Re: XPATH evaluation  (Nicolas Barbier <nicolas.barbier@gmail.com>)
List pgsql-hackers
Nicolas Barbier <nicolas.barbier@gmail.com> Friday 17 of June 2011 17:29:57
> 2011/6/17, Andrew Dunstan <andrew@dunslane.net>:
> > On 06/17/2011 10:55 AM, Radosław Smogura wrote:
> >> XML canonization preservs whitespaces, if I remember
> >> well, I think there is example.
> >>
> >> In any case if I will store image in XML (I've seen this), preservation
> >> of white spaces and new lines is important.
> >
> > If you store images you should encode them anyway, in base64 or hex.
>
> Whitespace that is not at certain obviously irrelevant places (such as
> right after "<", between attributes, outside of the whole document,
> etc), and that is not defined to be irrelevant by some schema (if the
> parser is schema-aware), is relevant. You cannot just muck around with
> it and consider that correct.
>
> > More generally, data that needs that sort of preservation should
> > possibly be in CDATA nodes.
>
> CDATA sections are just syntactic sugar (a form of escaping):
>
> <URL:http://www.w3.org/TR/xml-infoset/#omitted>
>
> "Appendix D: What is not in the Information Set
> [..]
> 19. The boundaries of CDATA marked sections."
>
> Therefore, there is not such thing as a "CDATA node" that would be
> different from "just text" (Infoset-wise).
>
> Note that that does not mean that binary data is never supposed to be
> altered or that all binary data is to be accepted: e.g., whether
> newlines are represented using "\n", "\r", or "\r\n" is irrelevant;
> also, binary data that is not valid according to the used encoding
> must of course not be accepted.
>
> Nicolas

I would like to send patch to remove formatting. How to deal with collapsing
blank nodes I don't know.

Regards,
Radek

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