Re: [basex-talk] BUG node comparison

Hi Christian,

thank you for the deep explanation. I've just got to use XQuery recently; my knowledge is primarily based on XPath 1.0 acquired 15y ago. I understand the underlying string value comparison of nodes/node sets. Even though performance was not my goal, thank you for the suggestion of 'is operator'.

However, I still don't understand, why the -w parameter should do the trick. I would expect the parsing is done once on the document load and $rootElement variable is just holding a document's node. Then string value of either $rootElement and parent::* should be identical for identical nodes. Do I miss something?

Thank you, Jan

-----Original Message----- From: Christian Grün christian.gruen@gmail.com Sent: Wednesday, May 26, 2021 11:41 To: ydyxeb@post.cz Cc: BaseX basex-talk@mailman.uni-konstanz.de Subject: Re: [basex-talk] BUG node comparison

Hi Jan,

Thanks for your feedback to the mailing list.

Your query will return the expected paths if you call BaseX as follows:

basex.bat -w -i datafile.xml queryfile.xq

A short explanation: By default, BaseX ignores whitespaces when parsing XML documents. By specifying -w, whitespace chopping can be suppresed [1,2]. If you want to permanently disable whitespace chopping, you can achieve that by adding "CHOP=false" option in your .basex configuration file [2]

A more comprehensive explanation (just ignore it if you are aware of all the details): In your query, you are checking if the string value of a parent element is identical to the string value of $rootElement. The following comparison is equivalent to yours:

//Section[parent::*/data() != $rootElement/data()]

This is the reason why it matters if the whitespace-only nodes will be parsed or not. – If your actual objective is to compare the XML structure, you could the following:

//Section[not(deep-equal(parent::*, $rootElement))]

The following solution compares node identities:

//Section[not(parent::* is $rootElement)]

Hope this helps Christian

[1] https://docs.basex.org/wiki/Command-Line_Options [2] https://docs.basex.org/wiki/Configuration

Using BaseX 9.5.1, cmd-line “basex.bat -i datafile.xml queryfile.xq” leads to no result at all. I’m convinced there should be result equivalent to the one of the online xquery tester (https://www.videlibri.de/cgi-bin/xidelcgi)

For a modified query using string comparison based on fn:path(), BaseX gives the expected result.

%%% query begin %%%

let $rootElement := /child::*

for $x in //Section[parent::* != $rootElement]

return fn:path($x)

%%% query end %%%

%%% data begin %%%

<root>

            <Section id="should not be reported 1" />

            <Section id="should not be reported 2">

                            <Section id="should be reported 1"/>

                            <a>

                                            <Section id="should be 

reported 2"/>

                            </a>

            </Section>

            <a>

                            <Section id="should be reported 3"/>

            </a>

</root>

%%% data end %%%

%%% modified query begin %%%

let $rootElementPath := fn:path(/child::*)

for $x in //Section[fn:path(parent::*) != $rootElementPath]

return fn:path($x)

%%% query end %%%

Kind regards

Jan Červák