[BUG] Cardinality error on wiki/blogs/eXist/XQuery31

[lguariento]

Hello,

the https://exist-db.org/exist/apps/wiki/blogs/eXist/XQuery31 link returns an error:

exerr:ERROR XPTY0004: The actual cardinality for parameter 1 does not match the cardinality declared in the function's signature: ($language as xs:string, $code as xs:string) item()*. Expected cardinality: exactly one, got 0. [at line 309, column 36, source: /db/apps/wiki/modules/atomic.xql]
In function:
	(xs:string, xs:string) [13:28:/db/apps/wiki/modules/atomic.xql]
	markdown:code(xs:string, map(*)) [450:34:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/markdown-0.7.1/content/markdown.xql]
	markdown:handle-block(xs:string, function(*)*, map(*)) [454:13:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/markdown-0.7.1/content/markdown.xql]
	markdown:handle-block(xs:string, function(*)*, map(*)) [461:9:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/markdown-0.7.1/content/markdown.xql]
	markdown:parse-blocks(xs:string*, map(*)) [138:30:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/markdown-0.7.1/content/markdown.xql]
	markdown:parse(xs:string?, map(*)+) [104:40:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/markdown-0.7.1/content/markdown.xql]
	atomic:get-content(element(atom:content)?, xs:boolean) [319:25:/db/apps/wiki/modules/atomic.xql]
	app:content(node(), map(*)) [-1:-1:/db/apps/wiki/modules/app.xql]
	templates:process-output(element(), map(*), item()*, element(function)) [211:9:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:call-by-introspection(element(), map(*), map(*), function(*)) [189:28:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:call(item(), element(), map(*)) [145:37:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [148:81:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [79:21:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	app:entries(node(), map(*), xs:string?, xs:string?, xs:string?, xs:int) [-1:-1:/db/apps/wiki/modules/app.xql]
	templates:process-output(element(), map(*), item()*, element(function)) [211:9:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:call-by-introspection(element(), map(*), map(*), function(*)) [189:28:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:call(item(), element(), map(*)) [145:37:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [237:13:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [148:81:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [148:81:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [148:81:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [148:81:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [148:81:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [148:81:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [428:17:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process-output(element(), map(*), item()*) [230:9:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process-output(element(), map(*), item()*, element(function)) [211:9:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:call-by-introspection(element(), map(*), map(*), function(*)) [189:28:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:call(item(), element(), map(*)) [137:36:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [133:51:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:process(node()*, map(*)) [90:9:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]
	templates:apply(node()+, function(*), map(*)?, map(*)?) [31:5:/home/existdb/exist-db.org/exist-distribution-5.3.1/etc/../data/expathrepo/shared-0.9.1/content/templates.xql]

[lguariento]

Ok, I'm getting somewhere. It looks as though there is some issue with the markdown rendering of codeblocks. So, for the XQuery31 blog, for example, if we reduce it to:

<div class="row">
    <div class="col-md-6">
        The current development version of eXistdb includes full support for the array data type and related features from the [XQuery 3.1 Candidate Recommendation](http://www.w3.org/TR/xquery-31/#id-arrays). In combination with maps, arrays allow for a more "natural" representation of JSON in XQuery. Processing JSON or interfacing with external services returning JSON has become a lot more straightforward.
        
        But even if you are only mildly interested in JSON, arrays are a welcome addition to the XQuery language, mainly because unlike sequences, arrays can be nested. I guess most XQuery programmers have encountered a situation in which it would have been nice to return a sequence of sequences from a function. And sometimes you may want to indicate that particular items in a result sequence are empty. With arrays you can do all that. Arrays may contain other arrays or maps, sequences or even the empty sequence as members.
    </div>
    <div class="col-md-6">
        <figure>
        <iframe width="560" height="315" src="https://www.youtube.com/embed/XqehyfyjYWA" frameborder="0" allowfullscreen></iframe>
        <figcaption>Recorded presentation of this article during the eXistdb user pre-conference in Prague</figcaption>
        </figure>
    </div>
</div>

# Array Constructors

Array constructors come in two flavors: square and curly constructors. The square constructor will look familiar to most people:

'''xquery
let $array := [1, (), (3, 4)]
return
    $array(3)
'''

It all goes through. It takes only adding a carriage return after $array(3)''' to break everything.

I also tested on another problematic blog post (travisci) and I got the same behaviour. Up to the first codeblock everything works fine. As soon as I insert more content after the codeblock everything falls apart.

*I replaced ` with ' for display's sake.

[lguariento]

Also, it is clear that this is now related to this issue, so we should keep either one or the other.

[lguariento]

I have been able to further isolate the issue. I think it's in this line of code. If I hardcode the language to something like 'xquery' or 'yaml' then the rendering takes place (although all the code blocks are white, but hey).

I have reverted back to previous versions of markdown.xql and found out that up until this it was rendering something (although with unrendered blocks / HTML). This pull seems to have introduced the current issue.

[lguariento]

I think I solved it or at least found the core of the issue. Taking the $ (end of line) out makes the script do what we want.

I also tried with this, to no avail.

As far as I can see, this:

    if (matches($block, "^`{3,}.*\n.*?`{3,}", "ms")) then
        let $tokens := analyze-string($block, "^`{3,}(.*?)\n(.*)`{3,}", "ms")

does the job.

*From wiki/blogs/eXist/XQuery31

Shall I open a pull request?

[joewiz]

Sure, I can review your PR.