$node//text()[1], why doesn't it return the 1st text node?
Wednesday, 2 March 2016 · 6 messages · last reply 8 Mar 2016
JE
This is a matter of precedence.
Quoted text · France Baril · 1 line
> <li>{ $node//text()[1] }</li>
Has the meaning of "return all text nodes, that are in first position of their encapsulating element". Consider the intermediate result after partial evaluation to be something like
("allo!"[1], "Il pleut des clous."[1])
Applying parenthesis as you proposed in #4 resolves the issue:
Quoted text · France Baril · 1 line
> <li>{ ($node//text())[1] }</li>
resulting in
("allo!", "Il pleut des clous.")[1]
instead.
This is not an issue in $5, as all text nodes are stored in a sequence (which is flattened), and you return the first result of the flattened sequence.
--
Jens Erat
Universität Konstanz
Kommunikations-, Infomations-, Medienzentrum (KIM)
Abteilung Basisdienste
D-78457 Konstanz
Mail: jens.erat at uni-konstanz.de
FB
France Baril2 Mar 2016 21:17 #
Hi,
I was having issues manipulating text nodes. I found a way around my issue, but I'm still thinking that my 1st syntax to get the first text node of a sequence should have worked.
My question is given all the example below, is #2 returning the expected value? I was expecting it would work like the syntax for elements in #3 and return the same result as #4 and #5
let $node := <p><b>allo!</b> Il pleut des clous.</p>
let $node2 := <ul><li>1</li><li>2</li></ul>
let $text-node := $node//text()
return
<ul>
<li>{$text-node}</li>
<li>{$node//text()[1]}</li>
<li>{$node2//li[1]}</li>
<li>{($node//text())[1]}</li>
<li>{$text-node[1]}</li>
<li>{$node//text()[1][1]}</li>
<li>{for $i in $node//text() return <span>{$i}</span>}</li>
<li>{for $i in $text-node return <span>{$i}</span>}</li>
</ul>
<ul>
<li>allo! Il pleut des clous.</li>
<li>allo! Il pleut des clous.</li>
<li>
<li>1</li>
</li>
<li>allo!</li>
<li>allo!</li>
<li>allo! Il pleut des clous.</li>
<li>
<span>allo!</span>
<span> Il pleut des clous.</span>
</li>
<li>
<span>allo!</span>
<span> Il pleut des clous.</span>
</li>
</ul>--
France Baril
Architecte documentaire / Documentation architect
france.baril at architextus.com
CG
And a little addition:
$node//text()[1]…is an abbreviation for…
$node/descendant-or-self::node()/child::text()[1]However, you are probably looking for:
$node/descendant::text()[1]It’s completely fine to use parentheseses, as in this case, your query will exactly be rewritten as shown above.
Quoted text · Jens Erat · 33 lines
On Wed, Mar 2, 2016 at 8:28 PM, Jens Erat <jens.erat at uni-konstanz.de> wrote: > This is a matter of precedence. > >> <li>{ $node//text()[1] }</li> > > Has the meaning of "return all text nodes, that are in first position of > their encapsulating element". Consider the intermediate result after > partial evaluation to be something like > > ("allo!"[1], "Il pleut des clous."[1]) > > Applying parenthesis as you proposed in #4 resolves the issue: > >> <li>{ ($node//text())[1] }</li> > > resulting in > > ("allo!", "Il pleut des clous.")[1] > > instead. > > This is not an issue in $5, as all text nodes are stored in a sequence > (which is flattened), and you return the first result of the flattened > sequence. > > -- > Jens Erat > Universität Konstanz > Kommunikations-, Infomations-, Medienzentrum (KIM) > Abteilung Basisdienste > D-78457 Konstanz > Mail: jens.erat at uni-konstanz.de >
FB
France Baril3 Mar 2016 19:23 #
Thanks for taking the time to look at this so quickly. I'm still unsure how #2 isn't a sequence if #3 is.
Anyhow, if it all works as intended, I'm fine with using a variable or () to make sure the returned nodes are cast into a sequence.
I'm just a bit surprised that text nodes and element nodes are returned differently.
Regards,
France
Quoted text · Christian Grün · 54 lines
On Wed, Mar 2, 2016 at 3:43 PM, Christian Grün <christian.gruen at gmail.com> wrote: > And a little addition: > > $node//text()[1] > > …is an abbreviation for… > > $node/descendant-or-self::node()/child::text()[1] > > However, you are probably looking for: > > $node/descendant::text()[1] > > It’s completely fine to use parentheseses, as in this case, your query > will exactly be rewritten as shown above. > > > > On Wed, Mar 2, 2016 at 8:28 PM, Jens Erat <jens.erat at uni-konstanz.de> > wrote: > > This is a matter of precedence. > > > >> <li>{ $node//text()[1] }</li> > > > > Has the meaning of "return all text nodes, that are in first position of > > their encapsulating element". Consider the intermediate result after > > partial evaluation to be something like > > > > ("allo!"[1], "Il pleut des clous."[1]) > > > > Applying parenthesis as you proposed in #4 resolves the issue: > > > >> <li>{ ($node//text())[1] }</li> > > > > resulting in > > > > ("allo!", "Il pleut des clous.")[1] > > > > instead. > > > > This is not an issue in $5, as all text nodes are stored in a sequence > > (which is flattened), and you return the first result of the flattened > > sequence. > > > > -- > > Jens Erat > > Universität Konstanz > > Kommunikations-, Infomations-, Medienzentrum (KIM) > > Abteilung Basisdienste > > D-78457 Konstanz > > Mail: jens.erat at uni-konstanz.de > > >
--
France Baril
Architecte documentaire / Documentation architect
france.baril at architextus.com
CG
Christian Grün4 Mar 2016 10:30 #
Quoted text · France Baril · 2 lines
> Thanks for taking the time to look at this so quickly. I'm still unsure how > #2 isn't a sequence if #3 is.
Do you mean the result of #2 and #3? All results (values) of XQuery expressions are "sequences" (with 0 or more items), so the result of #2 is a sequence as well.
Quoted text · France Baril · 2 lines
> I'm just a bit surprised that text nodes and element nodes are returned > differently.
This is actually not about text or element nodes, it’s about descendant vs. child axis:
The following two queries are identical:
$node//text()[1]
$node/descendant-or-self::node()/child::text()[1]If evaluated, you will get the first child text node of all nodes of $node. In contrast..
($node//text())[1]
$node/descendant::text()[1]..will give you the first descendant text node of $node. Do you see the difference?
Hope this helps,
Christian
FB
France Baril8 Mar 2016 22:24 #
Doh! Got it!
Thanks!
Quoted text · Christian Grün · 33 lines
On Fri, Mar 4, 2016 at 4:30 AM, Christian Grün <christian.gruen at gmail.com> wrote: > > Thanks for taking the time to look at this so quickly. I'm still unsure > how > > #2 isn't a sequence if #3 is. > > Do you mean the result of #2 and #3? All results (values) of XQuery > expressions are "sequences" (with 0 or more items), so the result of > #2 is a sequence as well. > > > I'm just a bit surprised that text nodes and element nodes are returned > > differently. > > This is actually not about text or element nodes, it’s about > descendant vs. child axis: > > The following two queries are identical: > > $node//text()[1] > $node/descendant-or-self::node()/child::text()[1] > > If evaluated, you will get the first child text node of all nodes of > $node. In contrast.. > > ($node//text())[1] > $node/descendant::text()[1] > > ..will give you the first descendant text node of $node. Do you see > the difference? > > Hope this helps, > Christian >
--
France Baril
Architecte documentaire / Documentation architect
france.baril at architextus.com
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