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tokenize($ip, '\.')!xs:integer(.), 0, function($n, $d) { 256 * $n + $d }, 0, map(xs:integer#1, tokenize($ip, '\.'))
[[Category:XQuery]]
update fold-left syntax
This page contains code snippets that mainly originate from our [https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk basex-talk] mailing list.
== Compact Notations ==
<code>if</code>/<code>not</code>/<code>else</code> constructs can look pretty verbose in XQuery.
However, some alternatives exist in order to make conditional code more compact:
* The [[XQuery 3.0#Simple Map Operator|Simple Map Operator]] can be used to trigger an action if a value has a single item. The following two expressions are equivalent:
<pre class="brush:xquery">
let $s := "X" return (
(: OLD :) if(count($s) = 1) then 'OK' else (),
(: NEW :) $s ! 'OK'
)
</pre>
In some cases, also the first solution can be written more compact. If we know that our input will always have 0-1 items, we can write <code>if(exists($s))</code>. If our input will never be an empty string, a zero, etc, it’s sufficient to write <code>if($s)</code>.
* If you want to choose the first non-empty item from two arguments, we can use the position predicate:
<pre class="brush:xquery">
let $s := "X" return (
(: OLD :) if(exists($s)) then $s else 'default',
(: NEW :) ($s, 'default')[1]
)
</pre>
Note that this only works if both of your inputs have zero or one items.
== Computed Elements ==
let $ip := '134.34.226.65'
return fold-left(
)
</pre>
find . | grep \.jpg$ | wc -l
</pre>
