Difference between revisions of "Utility Module"

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This [[Module Library|XQuery Module]] contains various utility and helper functions.
+
This [[Module Library|XQuery Module]] contains some utility and helper functions.
  
−
For all listed functions, equivalent expressions exist in standard XQuery, but code may be better readable with function calls:
+
With {{Announce|Version 11}}, many functions have been removed in favor of new features of XQuery 4:
  
−
<syntaxhighlight lang="xquery">
+
{|
−
(: standard XQuery :)
+
|- valign="top"
−
let $result := if(exists($sequence)) then $sequence else ('default', 'values')
+
| '''BaseX 10'''
−
return $result[last()]
+
| '''XQuery 4'''
−
 
+
|- valign="top"
−
(: XQuery with functions of this module :)
+
| {{Code|util:array-members}}
−
$sequence
+
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-array-members <code>array:members</code>]
−
=> util:or(('default', 'values'))
+
|- valign="top"
−
=> util:last()
+
| {{Code|util:array-values}}
−
</syntaxhighlight>
+
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-array-values <code>array:values</code>]
−
 
+
|- valign="top"
−
In addition, various query optimizations create calls to the utility functions.
+
| {{Code|util:chars}}
 +
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-chars <code>fn:characters</code>]
 +
|- valign="top"
 +
| {{Code|util:duplicates}}
 +
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-duplicate-values <code>fn:duplicate-values</code>]
 +
|- valign="top"
 +
| {{Code|util:init}}
 +
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-trunk <code>fn:trunk</code>]
 +
|- valign="top"
 +
| {{Code|util:intersperse}}
 +
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-intersperse <code>fn:intersperse</code>]
 +
|- valign="top"
 +
| {{Code|util:item}}
 +
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-items-at <code>fn:items-at</code>]
 +
|- valign="top"
 +
| {{Code|util:last}}
 +
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-foot <code>fn:foot</code>]
 +
|- valign="top"
 +
| {{Code|util:map-entries}}
 +
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-map-entries <code>map:entries</code>]
 +
|- valign="top"
 +
| {{Code|util:map-values}}
 +
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-map-values <code>map:values</code>]
 +
|- valign="top"
 +
| {{Code|util:or}}
 +
| <code>$expr1 otherwise $expr2
 +
|- valign="top"
 +
| {{Code|util:replicate}}
 +
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-replicate <code>fn:replicate</code>]
 +
|}
  
 
=Conventions=
 
=Conventions=
Line 20: Line 49:
 
All functions and errors in this module and errors are assigned to the <code><nowiki>http://basex.org/modules/util</nowiki></code> namespace, which is statically bound to the {{Code|util}} prefix.<br/>
 
All functions and errors in this module and errors are assigned to the <code><nowiki>http://basex.org/modules/util</nowiki></code> namespace, which is statically bound to the {{Code|util}} prefix.<br/>
  
−
=Conditions=
+
=Conditions and Ranges=
  
 
==util:if==
 
==util:if==
Line 28: Line 57:
 
| width='120' | '''Signature'''
 
| width='120' | '''Signature'''
 
|<pre>util:if(
 
|<pre>util:if(
−
   $condition  as item()*
+
   $condition  as item()*,
−
   $then      as item()*
+
   $then      as item()*,
 
   $else      as item()*  := ()
 
   $else      as item()*  := ()
 
) as item()*</pre>
 
) as item()*</pre>
Line 36: Line 65:
 
|Alternative writing for the if/then/else expression:
 
|Alternative writing for the if/then/else expression:
 
* If the ''effective boolean value'' of {{Code|$condition}} is true, the {{Code|$then}} branch will be evaluated.
 
* If the ''effective boolean value'' of {{Code|$condition}} is true, the {{Code|$then}} branch will be evaluated.
−
* Otherwise, {{Code|$else}} will be evaluated. If no third argument is supplied, an empty sequence will be returned.
+
* Otherwise, {{Code|$else}} will be evaluated. If the third argument is omitted, an empty sequence will be returned.
 
|- valign="top"
 
|- valign="top"
 
| '''Examples'''
 
| '''Examples'''
Line 42: Line 71:
 
* <code>util:if(true(), 123, 456)</code> returns {{Code|123}}.
 
* <code>util:if(true(), 123, 456)</code> returns {{Code|123}}.
 
* <code>util:if(0, 'wrong!')</code> returns an empty sequence.
 
* <code>util:if(0, 'wrong!')</code> returns an empty sequence.
−
|}
 
−
 
−
==util:or==
 
−
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:or(
 
−
  $items    as item()*
 
−
  $default  as item()*
 
−
) as item()*</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Returns {{Code|$items}} if it is a non-empty sequence. Otherwise, returns {{Code|$default}}. Equivalent to the following expressions:
 
−
<syntaxhighlight lang="xquery">
 
−
if(exists($items)) then $items else $default,
 
−
(: Elvis operator :)
 
−
$items ?: $default
 
−
</syntaxhighlight>
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
|
 
−
* <code>util:or(123, 456)</code> returns {{Code|123}}.
 
−
* <code>util:or(1[. = 0], -1)</code> returns {{Code|-1}}.
 
 
|}
 
|}
  
 
==util:count-within==
 
==util:count-within==
−
 
−
{{Announce|Updated with BaseX 10:}} Renamed from {{Code|util:within}}
 
  
 
{| width='100%'
 
{| width='100%'
Line 76: Line 79:
 
| width='120' | '''Signature'''
 
| width='120' | '''Signature'''
 
|<pre>util:count-within(
 
|<pre>util:count-within(
−
   $sequence  as item()*
+
   $sequence  as item()*,
−
   $min      as xs:integer
+
   $min      as xs:integer,
 
   $max      as xs:integer  := ()
 
   $max      as xs:integer  := ()
 
) as xs:boolean</pre>
 
) as xs:boolean</pre>
Line 83: Line 86:
 
| '''Summary'''
 
| '''Summary'''
 
|Checks if the specified {{Code|$sequence}} has at least {{Code|$min}} and, optionally, at most {{Code|$max}} items. Equivalent to:
 
|Checks if the specified {{Code|$sequence}} has at least {{Code|$min}} and, optionally, at most {{Code|$max}} items. Equivalent to:
−
<syntaxhighlight lang="xquery">
+
<pre lang='xquery'>
 
let $count := count($sequence)
 
let $count := count($sequence)
 
return $count >= $min and $count <= $max
 
return $count >= $min and $count <= $max
−
</syntaxhighlight>
+
</pre>
 
|- valign="top"
 
|- valign="top"
 
| '''Examples'''
 
| '''Examples'''
Line 92: Line 95:
 
* <code>util:count-within(('a', 'b', 'c'), 2)</code> returns {{Code|true}}.
 
* <code>util:count-within(('a', 'b', 'c'), 2)</code> returns {{Code|true}}.
 
* <code>util:count-within((1 to 1000000000)[. < 10], 3, 6)</code> returns {{Code|true}}.
 
* <code>util:count-within((1 to 1000000000)[. < 10], 3, 6)</code> returns {{Code|true}}.
−
|}
 
−
 
−
=Positional Access=
 
−
 
−
==util:item==
 
−
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:item(
 
−
  $sequence  as item()*
 
−
  $position  as xs:double
 
−
) as item()?</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Returns the item from {{Code|$sequence}} at the specified {{Code|$position}}. Equivalent to:
 
−
<syntaxhighlight lang="xquery">
 
−
$sequence[$position]
 
−
</syntaxhighlight>
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
|
 
−
* <code>util:item(reverse(1 to 5), 1)</code> returns <code>5</code>.
 
−
* <code>util:item(('a','b'), 0)</code> returns an empty sequence.
 
 
|}
 
|}
  
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| width='120' | '''Signature'''
 
| width='120' | '''Signature'''
 
|<pre>util:range(
 
|<pre>util:range(
−
   $sequence  as item()*
+
   $sequence  as item()*,
−
   $first    as xs:double
+
   $first    as xs:double,
 
   $last      as xs:double
 
   $last      as xs:double
 
) as item()*</pre>
 
) as item()*</pre>
Line 131: Line 110:
 
| '''Summary'''
 
| '''Summary'''
 
|Returns items from {{Code|$sequence}}, starting at position {{Code|$first}} and ending at {{Code|$last}}. Equivalent to:
 
|Returns items from {{Code|$sequence}}, starting at position {{Code|$first}} and ending at {{Code|$last}}. Equivalent to:
−
<syntaxhighlight lang="xquery">
+
<pre lang='xquery'>
 
subsequence($sequence, $first, $last - $first + 1)
 
subsequence($sequence, $first, $last - $first + 1)
−
</syntaxhighlight>
+
</pre>
 
|- valign="top"
 
|- valign="top"
 
| '''Examples'''
 
| '''Examples'''
 
|
 
|
 
* <code>util:range(//item, 11, 20)</code> returns all path results from (if available) position 11 to 20.
 
* <code>util:range(//item, 11, 20)</code> returns all path results from (if available) position 11 to 20.
−
|}
 
−
 
−
==util:last==
 
−
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:last(
 
−
  $sequence  as item()*
 
−
) as item()?</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Returns last item of a {{Code|$sequence}}. Equivalent to:
 
−
<syntaxhighlight lang="xquery">
 
−
$sequence[last()]
 
−
</syntaxhighlight>
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
|
 
−
* <code>util:last(reverse(1 to 100))</code> returns <code>1</code>.
 
−
|}
 
−
 
−
==util:init==
 
−
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:init(
 
−
  $sequence  as item()*
 
−
) as item()*</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Returns all items of a {{Code|$sequence}} except for the last one. Equivalent to:
 
−
<syntaxhighlight lang="xquery">
 
−
$sequence[position() < last()]
 
−
</syntaxhighlight>
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
|
 
−
* <code>util:init(1 to 4)</code> returns <code>1 2 3</code>.
 
 
|}
 
|}
  
Line 193: Line 132:
 
| '''Summary'''
 
| '''Summary'''
 
|Returns nodes in ''distinct document order'': duplicate nodes will be removed, and the remaining nodes will be returned in [https://www.w3.org/TR/xquery-31/#dt-document-order document order]. As results of path expressions are brought distinct document order before they are returned, the function is equivalent to:
 
|Returns nodes in ''distinct document order'': duplicate nodes will be removed, and the remaining nodes will be returned in [https://www.w3.org/TR/xquery-31/#dt-document-order document order]. As results of path expressions are brought distinct document order before they are returned, the function is equivalent to:
−
<syntaxhighlight lang="xquery">
+
<pre lang='xquery'>
 
$nodes/self::node()
 
$nodes/self::node()
−
</syntaxhighlight>
+
</pre>
 
|}
 
|}
  
Line 209: Line 148:
 
| '''Summary'''
 
| '''Summary'''
 
|Returns the document nodes of the specified {{Code|$nodes}}. The path expression <code>/abc</code> is internally represented as <code>util:root(.)/abc</code>. Equivalent to:
 
|Returns the document nodes of the specified {{Code|$nodes}}. The path expression <code>/abc</code> is internally represented as <code>util:root(.)/abc</code>. Equivalent to:
−
<syntaxhighlight lang="xquery">
+
<pre lang='xquery'>
 
$nodes ! /
 
$nodes ! /
−
</syntaxhighlight>
+
</pre>
 
|}
 
|}
  
Line 220: Line 159:
 
| width='120' | '''Signature'''
 
| width='120' | '''Signature'''
 
|<pre>util:strip-namespaces(
 
|<pre>util:strip-namespaces(
−
   $node      as node()
+
   $node      as node(),
 
   $prefixes  as xs:string*  := ()
 
   $prefixes  as xs:string*  := ()
 
) as node()</pre>
 
) as node()</pre>
Line 230: Line 169:
 
|
 
|
 
* Remove all namespaces from an element and its descendants:
 
* Remove all namespaces from an element and its descendants:
−
<syntaxhighlight lang="xquery">
+
<pre lang='xquery'>
 
util:strip-namespaces(<xml xmlns='uri' xmlns:prefix='uri2' prefix:name='value'><prefix:child/></xml>)
 
util:strip-namespaces(<xml xmlns='uri' xmlns:prefix='uri2' prefix:name='value'><prefix:child/></xml>)
  
 
(: yields :)
 
(: yields :)
 
<xml name='value'><child/></xml>
 
<xml name='value'><child/></xml>
−
</syntaxhighlight>
+
</pre>
 
* Remove all default namespaces:
 
* Remove all default namespaces:
−
<syntaxhighlight lang="xquery">
+
<pre lang='xquery'>
 
<xml xmlns='uri1'><child xmlns='uri2'/></xml>
 
<xml xmlns='uri1'><child xmlns='uri2'/></xml>
 
=> util:strip-namespaces('')
 
=> util:strip-namespaces('')
−
</syntaxhighlight>
+
</pre>
−
|}
 
−
 
 
−
=Array and Map Functions=
 
−
 
 
−
==util:array-members==
 
−
 
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:array-members(
 
−
  $array  as array(*)
 
−
) as array(*)*</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Returns each member of an {{Code|$array}} as a new array. Equivalent to:
 
−
<syntaxhighlight lang="xquery">
 
−
for $a in 1 to array:size($array)
 
−
return [ $array($a) ]
 
−
</syntaxhighlight>
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
|
 
−
* Returns three elements with the member values as concatenated text node.
 
−
<syntaxhighlight lang="xquery">
 
−
let $array := [ (), 2, (3, 4) ]
 
−
for $member in util:array-members($array)
 
−
return element numbers { $member }
 
−
</syntaxhighlight>
 
−
|}
 
−
 
 
−
==util:array-values==
 
−
 
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:array-values(
 
−
  $array  as array(*)
 
−
) as item()*</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Returns all members of an {{Code|$array}} as a sequence. Equivalent to:
 
−
<syntaxhighlight lang="xquery">
 
−
$array ? *
 
−
</syntaxhighlight>
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
|
 
−
* Returns the array members as two items:
 
−
<syntaxhighlight lang="xquery">
 
−
let $array := [ (), 2, [ 3, 4 ] ]
 
−
return util:array-values($array)
 
−
</syntaxhighlight>
 
−
|}
 
−
 
 
−
==util:map-entries==
 
−
 
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:map-entries(
 
−
  $map  as map(*)
 
−
) as map(xs:string, item()*)*</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Returns each entry of a {{Code|$map}} as a new map, each with a {{Code|key}} and {{Code|value}} entry. Equivalent to:
 
−
<syntaxhighlight lang="xquery">
 
−
map:for-each($map, function($key, $value) {
 
−
  map { "key": $key, "value": $value }
 
−
})
 
−
</syntaxhighlight>
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
|
 
−
* Returns three elements named by the key of the map, and with the entries as concatenated text node.
 
−
<syntaxhighlight lang="xquery">
 
−
let $map := map { 'a': (), 'b': 2, 'c': [ 3, 4 ] }
 
−
for $entry in util:map-entries($map)
 
−
return element { $entry?key } { string-join($entry?value) }
 
−
</syntaxhighlight>
 
−
|}
 
−
 
 
−
==util:map-values==
 
−
 
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:map-values(
 
−
  $map  as map(*)
 
−
) as item()*</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Returns all values of a {{Code|$map}} as a sequence. Equivalent to:
 
−
<syntaxhighlight lang="xquery">
 
−
$map ? *
 
−
</syntaxhighlight>
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
|
 
−
* Returns the map values as two items:
 
−
<syntaxhighlight lang="xquery">
 
−
let $map := map { 'a': (), 'b': 2, 'c': [ 3, 4 ] }
 
−
return util:map-values($map)
 
−
</syntaxhighlight>
 
−
|}
 
−
 
 
−
=Helper Functions=
 
−
 
 
−
==util:replicate==
 
−
 
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:replicate(
 
−
  $input    as item()*
 
−
  $count    as xs:integer
 
−
  $multiple  as xs:boolean  := ()
 
−
) as item()*</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Evaluates {{Code|$input}} and returns the result {{Code|$count}} times. Unless {{Code|$multiple}} is enabled, the input expression is only evaluated once.  Equivalent expressions:
 
−
<syntaxhighlight lang="xquery">
 
−
util:replicate($input, $count, true()),
 
−
(1 to $count) ! $input
 
−
</syntaxhighlight>
 
−
|- valign="top"
 
−
| '''Errors'''
 
−
|{{Error|negative|#Errors}} The specified number is negative.
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
|
 
−
* <code>util:replicate('A', 3)</code> returns <code>A A A</code>.
 
−
* In the following query, a single new element node is constructed, and {{Code|true}} is returned:
 
−
<syntaxhighlight lang="xquery">
 
−
let $nodes := util:replicate(<node/>, 2)
 
−
return $nodes[1] is $nodes[2]
 
−
</syntaxhighlight>
 
−
* In this query, two nodes are constructed, and the result is {{Code|false}}:
 
−
<syntaxhighlight lang="xquery">
 
−
let $nodes := util:replicate(<node/>, 2, true())
 
−
return $nodes[1] is $nodes[2]
 
−
</syntaxhighlight>
 
−
|}
 
−
 
 
−
==util:intersperse==
 
−
 
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:intersperse(
 
−
  $items      as item()*
 
−
  $separator  as item()*
 
−
) as item()*</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Inserts the defined {{Code|$separator}} between the {{Code|$items}} of a sequence and returns the resulting sequence. Equivalent to:
 
−
<syntaxhighlight lang="xquery">
 
−
head($items), for $item in tail($items) return ($separator, $item)
 
−
</syntaxhighlight>
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
| Inserts semicolon strings between the three input items:
 
−
<syntaxhighlight lang="xquery">
 
−
fn:intersperse((<_>1</_>, <_>2</_>, <_>3</_>), '; ')
 
−
</syntaxhighlight>
 
−
|}
 
−
 
 
−
==util:duplicates==
 
−
 
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:duplicates(
 
−
  $sequence  as item()*
 
−
  $collation  as xs:string  := ()
 
−
) as xs:anyAtomicType*</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Returns duplicate values in a {{Code|$sequence}}. See [https://www.w3.org/TR/xpath-functions-31/#func-distinct-values fn:distinct-values] for the applied equality rules and the usage of the {{Code|$collation}} argument.
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
|
 
−
* <code>util:duplicates((1, 2, 1, 1))</code> returns <code>1</code>.
 
−
|}
 
−
 
 
−
==util:chars==
 
−
 
 
−
{| width='100%'
 
−
|- valign="top"
 
−
| width='120' | '''Signature'''
 
−
|<pre>util:chars(
 
−
  $string  as xs:string?
 
−
) as xs:string*</pre>
 
−
|- valign="top"
 
−
| '''Summary'''
 
−
|Returns all characters of a {{Code|$string}} as a sequence. Equivalent to:
 
−
<syntaxhighlight lang="xquery">
 
−
for $cp in string-to-codepoints($string)
 
−
return codepoints-to-string($cp)
 
−
</syntaxhighlight>
 
−
|- valign="top"
 
−
| '''Examples'''
 
−
|
 
−
* <code>util:chars('AB')</code> returns the two strings <code>A</code> and <code>B</code>.
 
 
|}
 
|}
  
Line 457: Line 193:
  
 
=Changelog=
 
=Changelog=
 +
 +
;Version 11.0
 +
* Removed: {{Code|util:array-members}}, {{Code|util:array-values}}, {{Code|util:chars}}, {{Code|util:duplicates}}, {{Code|util:init}}, {{Code|util:intersperse}}, {{Code|util:item}}, {{Code|util:last}}, {{Code|util:map-entries}}, {{Code|util:map-values}}, {{Code|util:replicate}}
  
 
;Version 9.7
 
;Version 9.7
Line 463: Line 202:
  
 
;Version 9.5
 
;Version 9.5
−
* Added: {{Function||util:intersperse}}, {{Function||util:within}}, {{Function||util:duplicates}}, {{Function||util:array-members}}, {{Function||util:array-values}}, {{Function||util:map-entries}}, {{Function||util:map-values}}
+
* Added: {{Code|util:intersperse}}, {{Code|util:within}}, {{Code|util:duplicates}}, {{Code|util:array-members}}, {{Code|util:array-values}}, {{Code|util:map-entries}}, {{Code|util:map-values}}
−
* Updated: {{Function||util:replicate}}: Third argument added.
+
* Updated: {{Code|util:replicate}}: Third argument added.
  
 
;Version 9.4
 
;Version 9.4
Line 473: Line 212:
  
 
;Version 9.2
 
;Version 9.2
−
* Added: {{Function||util:chars}}, {{Function||util:init}}
+
* Added: {{Code|util:chars}}, {{Code|util:init}}
−
* Updated: {{Function||util:item}}, {{Function||util:last}}, {{Function||util:range}} renamed (before: {{Code|util:item-at}}, {{Code|util:item-range}}, {{Code|util:last-from}})
+
* Updated: {{Code|util:item}}, {{Code|util:last}}, {{Function||util:range}} renamed (before: {{Code|util:item-at}}, {{Code|util:item-range}}, {{Code|util:last-from}})
  
 
;Version 9.1
 
;Version 9.1
−
* Added: {{Function||util:if}}, {{Function||util:or}}
+
* Added: {{Function||util:if}}, {{Code|util:or}}
  
 
;Version 9.0
 
;Version 9.0
−
* Added: {{Function||util:replicate}}
+
* Added: {{Code|util:replicate}}
  
 
The Module was introduced with Version 8.5.
 
The Module was introduced with Version 8.5.

Latest revision as of 14:36, 5 December 2023

This XQuery Module contains some utility and helper functions.

With Version 11, many functions have been removed in favor of new features of XQuery 4:

BaseX 10 XQuery 4
util:array-members array:members
util:array-values array:values
util:chars fn:characters
util:duplicates fn:duplicate-values
util:init fn:trunk
util:intersperse fn:intersperse
util:item fn:items-at
util:last fn:foot
util:map-entries map:entries
util:map-values map:values
util:or $expr1 otherwise $expr2
util:replicate fn:replicate

Conventions[edit]

All functions and errors in this module and errors are assigned to the http://basex.org/modules/util namespace, which is statically bound to the util prefix.

Conditions and Ranges[edit]

util:if[edit]

Signature 
util:if(
  $condition  as item()*,
  $then       as item()*,
  $else       as item()*  := ()
) as item()*
Summary Alternative writing for the if/then/else expression:
  • If the effective boolean value of $condition is true, the $then branch will be evaluated.
  • Otherwise, $else will be evaluated. If the third argument is omitted, an empty sequence will be returned.
Examples
  • util:if(true(), 123, 456) returns 123.
  • util:if(0, 'wrong!') returns an empty sequence.

util:count-within[edit]

Signature 
util:count-within(
  $sequence  as item()*,
  $min       as xs:integer,
  $max       as xs:integer  := ()
) as xs:boolean
Summary Checks if the specified $sequence has at least $min and, optionally, at most $max items. Equivalent to: 
let $count := count($sequence)
return $count >= $min and $count <= $max
Examples
  • util:count-within(('a', 'b', 'c'), 2) returns true.
  • util:count-within((1 to 1000000000)[. < 10], 3, 6) returns true.

util:range[edit]

Signature 
util:range(
  $sequence  as item()*,
  $first     as xs:double,
  $last      as xs:double
) as item()*
Summary Returns items from $sequence, starting at position $first and ending at $last. Equivalent to: 
subsequence($sequence, $first, $last - $first + 1)
Examples
  • util:range(//item, 11, 20) returns all path results from (if available) position 11 to 20.

Node Functions[edit]

util:ddo[edit]

Signature 
util:ddo(
  $nodes  as node()*
) as node()*
Summary Returns nodes in distinct document order: duplicate nodes will be removed, and the remaining nodes will be returned in document order. As results of path expressions are brought distinct document order before they are returned, the function is equivalent to: 
$nodes/self::node()

util:root[edit]

Signature 
util:root(
  $nodes  as node()*
) as document-node()*
Summary Returns the document nodes of the specified $nodes. The path expression /abc is internally represented as util:root(.)/abc. Equivalent to: 
$nodes ! /

util:strip-namespaces[edit]

Signature 
util:strip-namespaces(
  $node      as node(),
  $prefixes  as xs:string*  := ()
) as node()
Summary Removes namespaces with the specified $prefixes from the supplied $node. An empty string can be supplied to remove the default namespace. If no prefixes are specified, all namespaces will be removed.
Examples
  • Remove all namespaces from an element and its descendants:
util:strip-namespaces(<xml xmlns='uri' xmlns:prefix='uri2' prefix:name='value'><prefix:child/></xml>)

(: yields :)
<xml name='value'><child/></xml>
  • Remove all default namespaces:
<xml xmlns='uri1'><child xmlns='uri2'/></xml>
=> util:strip-namespaces('')

Errors[edit]

Code Description
negative The specified number is negative.

Changelog[edit]

Version 11.0
  • Removed: util:array-members, util:array-values, util:chars, util:duplicates, util:init, util:intersperse, util:item, util:last, util:map-entries, util:map-values, util:replicate
Version 9.7
Version 9.5
  • Added: util:intersperse, util:within, util:duplicates, util:array-members, util:array-values, util:map-entries, util:map-values
  • Updated: util:replicate: Third argument added.
Version 9.4
Version 9.3
Version 9.2
  • Added: util:chars, util:init
  • Updated: util:item, util:last, util:range renamed (before: util:item-at, util:item-range, util:last-from)
Version 9.1
Version 9.0
  • Added: util:replicate

The Module was introduced with Version 8.5.

Retrieved from "http://docs.basex.org/index.php?title=Utility_Module&oldid=16918"