Difference between revisions of "Utility Module"

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This [[Module Library|XQuery Module]] contains various small utility and helper functions. Please note that some of the functions are used for internal query rewritings. They may be renamed or moved to other modules in future versions of BaseX.
+
This [[Module Library|XQuery Module]] contains some utility and helper functions.
 +
 
 +
With {{Announce|Version 11}}, many functions have been removed in favor of new features of XQuery 4:
 +
 
 +
{|
 +
|- valign="top"
 +
| '''BaseX 10'''
 +
| '''XQuery 4'''
 +
|- valign="top"
 +
| {{Code|util:array-members}}
 +
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-array-members <code>array:members</code>]
 +
|- valign="top"
 +
| {{Code|util:array-values}}
 +
| [https://qt4cg.org/specifications/xpath-functions-40/Overview.html#func-array-values <code>array:values</code>]
 +
|- valign="top"
 +
| {{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 5: 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==
  
 
{| width='100%'
 
{| width='100%'
−
|-
+
|- valign="top"
−
| width='120' | '''Signatures'''
+
| width='120' | '''Signature'''
−
|{{Func|util:if|$condition as item()*, $then as item()*|item()*}}<br/>{{Func|util:if|$condition as item()*, $then as item()*, $else as item()*|item()*}}<br/>
+
|<pre>util:if(
−
|-
+
  $condition as item()*,
 +
  $then       as item()*,
 +
  $else       as item()* := ()
 +
) as item()*</pre>
 +
|- valign="top"
 
| '''Summary'''
 
| '''Summary'''
 
|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"
 
| '''Examples'''
 
| '''Examples'''
 
|
 
|
Line 25: Line 73:
 
|}
 
|}
  
−
==util:or==
+
==util:count-within==
−
 
 
−
{| width='100%'
 
−
|-
 
−
| width='120' | '''Signatures'''
 
−
|{{Func|util:or|$items as item()*, $default as item()*|item()*}}
 
−
|-
 
−
| '''Summary'''
 
−
|Returns {{Code|$items}} if it is a non-empty sequence. Otherwise, returns {{Code|$default}}. The function is equivalent to one of the following expressions:
 
−
* <code>if(exists($items)) then $items else $default</code>
 
−
* <code>$items ?: $default</code> (see [[XQuery Extensions#Elvis Operator|Elvis Operator]] for more details)
 
−
|-
 
−
| '''Examples'''
 
−
|
 
−
* <code>util:or(123, 456)</code> returns {{Code|123}}.
 
−
* <code>util:or(1[. = 0], -1)</code> returns {{Code|-1}}.
 
−
|}
 
−
 
 
−
=Positional Access=
 
−
 
 
−
==util:item==
 
  
 
{| width='100%'
 
{| width='100%'
−
|-
+
|- valign="top"
−
| width='120' | '''Signatures'''
+
| width='120' | '''Signature'''
−
|{{Func|util:item|$sequence as item()*, $position as xs:double|item()?}}<br/>
+
|<pre>util:count-within(
−
|-
+
  $sequence as item()*,
 +
  $min      as xs:integer,
 +
  $max      as xs:integer  := ()
 +
) as xs:boolean</pre>
 +
|- valign="top"
 
| '''Summary'''
 
| '''Summary'''
−
|Returns the item from {{Code|$sequence}} at the specified {{Code|$position}}. Equivalent to <code>$sequence[$position]</code>.
+
|Checks if the specified {{Code|$sequence}} has at least {{Code|$min}} and, optionally, at most {{Code|$max}} items. Equivalent to:
−
|-
+
<pre lang='xquery'>
 +
let $count := count($sequence)
 +
return $count >= $min and $count <= $max
 +
</pre>
 +
|- valign="top"
 
| '''Examples'''
 
| '''Examples'''
 
|
 
|
−
* <code>util:item(reverse(1 to 5), 1)</code> returns <code>5</code>.
+
* <code>util:count-within(('a', 'b', 'c'), 2)</code> returns {{Code|true}}.
−
* <code>util:item(('a','b'), 0)</code> returns an empty sequence.
+
* <code>util:count-within((1 to 1000000000)[. < 10], 3, 6)</code> returns {{Code|true}}.
 
|}
 
|}
  
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{| width='100%'
 
{| width='100%'
−
|-
+
|- valign="top"
−
| width='120' | '''Signatures'''
+
| width='120' | '''Signature'''
−
|{{Func|util:range|$sequence as item()*, $first as xs:double, $last as xs:double|item()*}}<br/>
+
|<pre>util:range(
−
|-
+
  $sequence as item()*,
 +
  $first     as xs:double,
 +
  $last     as xs:double
 +
) as item()*</pre>
 +
|- valign="top"
 
| '''Summary'''
 
| '''Summary'''
−
|Returns items from {{Code|$sequence}}, starting at position {{Code|$first}} and ending at {{Code|$last}}. Equivalent to <code>subsequence($sequence, $first, $last - $first + 1)</code>.
+
|Returns items from {{Code|$sequence}}, starting at position {{Code|$first}} and ending at {{Code|$last}}. Equivalent to:
−
|-
+
<pre lang='xquery'>
 +
subsequence($sequence, $first, $last - $first + 1)
 +
</pre>
 +
|- 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%'
 
−
|-
 
−
| width='120' | '''Signatures'''
 
−
|{{Func|util:last|$sequence as item()*|item()?}}<br/>
 
−
|-
 
−
| '''Summary'''
 
−
|Returns last item of a {{Code|$sequence}}. Equivalent to <code>$sequence[last()]</code>.
 
−
|-
 
−
| '''Examples'''
 
−
|
 
−
* <code>util:last(reverse(1 to 100))</code> returns <code>1</code>.
 
−
|}
 
−
 
−
==util:init==
 
−
 
−
{| width='100%'
 
−
|-
 
−
| width='120' | '''Signatures'''
 
−
|{{Func|util:init|$sequence as item()*|item()*}}<br/>
 
−
|-
 
−
| '''Summary'''
 
−
|Returns all items of a {{Code|$sequence}} except for the last one. Equivalent to <code>$sequence[position() < last()]</code>.
 
−
|-
 
−
| '''Examples'''
 
−
|
 
−
* <code>util:init(1 to 4)</code> returns <code>1 2 3</code>.
 
 
|}
 
|}
  
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{| width='100%'
 
{| width='100%'
−
|-
+
|- valign="top"
−
| width='120' | '''Signatures'''
+
| width='120' | '''Signature'''
−
|{{Func|util:ddo|$nodes as node()*|node()*}}<br/>
+
|<pre>util:ddo(
−
|-
+
  $nodes as node()*
 +
) as node()*</pre>
 +
|- valign="top"
 
| '''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]. All results of path expression are in distinct document order, so the function is equivalent to the expression <code>$nodes/self::node()</code>.
+
|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:
 +
<pre lang='xquery'>
 +
$nodes/self::node()
 +
</pre>
 
|}
 
|}
  
−
{{Mark|Introduced with Version 9.4:}}
+
==util:root==
  
 
{| width='100%'
 
{| width='100%'
−
|-
+
|- valign="top"
−
| width='120' | '''Signatures'''
+
| width='120' | '''Signature'''
−
|{{Func|util:root|$nodes as node()*|document-node()*}}<br/>
+
|<pre>util:root(
−
|-
+
  $nodes as node()*
 +
) as document-node()*</pre>
 +
|- valign="top"
 
| '''Summary'''
 
| '''Summary'''
−
|Returns the document nodes of the specified {{Code|$nodes}}. The function is equivalent to the expression <code>$nodes ! /</code>. The path expression <code>/abc</code>
+
|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:
−
is internally represented as <code>util:root(.)/abc</code.
+
<pre lang='xquery'>
−
 
+
$nodes ! /
 +
</pre>
 
|}
 
|}
  
−
=Helper Functions=
+
==util:strip-namespaces==
−
 
 
−
==util:replicate==
 
−
 
 
−
{{Mark|Updated with Version 9.5:}} Third argument added.
 
  
 
{| width='100%'
 
{| width='100%'
−
|-
+
|- valign="top"
−
| width='120' | '''Signatures'''
+
| width='120' | '''Signature'''
−
|{{Func|util:replicate|$input as item()*, $count as xs:integer|item()*}}<br/>{{Func|util:replicate|$input as item()*, $count as xs:integer, $multiple as xs:boolean|item()*}}
+
|<pre>util:strip-namespaces(
−
|-
+
  $node      as node(),
 +
  $prefixes  as xs:string* := ()
 +
) as node()</pre>
 +
|- valign="top"
 
| '''Summary'''
 
| '''Summary'''
−
|Evaluates {{Code|$input}} and returns the result {{Code|$count}} times. Unless {{Code|$multiple}} is enabled, the input expression is only evaluated once. The function call <code>util:replicate($input, $count, true())</code> is equivalent to <code>(1 to $count) ! $input</code>.
+
|Removes namespaces with the specified <code>$prefixes</code> from the supplied <code>$node</code>. An empty string can be supplied to remove the default namespace. If no prefixes are specified, all namespaces will be removed.
−
|-
+
|- valign="top"
−
| '''Errors'''
 
−
|{{Error|negative|#Errors}} The specified number is negative.
 
−
|-
 
 
| '''Examples'''
 
| '''Examples'''
 
|
 
|
−
* <code>util:replicate('A', 3)</code> returns <code>A A A</code>.
+
* Remove all namespaces from an element and its descendants:
−
* In the following query, a single new element node is constructed, and {{Code|true}} is returned:
+
<pre lang='xquery'>
−
<syntaxhighlight lang="xquery">
+
util:strip-namespaces(<xml xmlns='uri' xmlns:prefix='uri2' prefix:name='value'><prefix:child/></xml>)
−
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:chars==
+
(: yields :)
−
 
+
<xml name='value'><child/></xml>
−
{| width='100%'
+
</pre>
−
|-
+
* Remove all default namespaces:
−
| width='120' | '''Signatures'''
+
<pre lang='xquery'>
−
|{{Func|util:chars|$string as xs:string|xs:string*}}<br/>
+
<xml xmlns='uri1'><child xmlns='uri2'/></xml>
−
|-
+
=> util:strip-namespaces('')
−
| '''Summary'''
+
</pre>
−
|Returns all characters of a {{Code|$string}} as a sequence. Equivalent to <code>string-to-codepoints($string) ! codepoints-to-string(.)</code>.
 
−
|-
 
−
| '''Examples'''
 
−
|
 
−
* <code>util:chars('AB')</code> returns the two strings <code>A</code> and <code>B</code>.
 
 
|}
 
|}
  
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! width="110"|Code
 
! width="110"|Code
 
|Description
 
|Description
−
|-
+
|- valign="top"
 
|{{Code|negative}}
 
|{{Code|negative}}
 
|The specified number is negative.
 
|The specified number is negative.
Line 190: 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
 +
* Added: {{Function||util:strip-namespaces}}
 +
* Updated: {{Function||util:count-within}}: Renamed from {{Code|util:within}}.
  
 
;Version 9.5
 
;Version 9.5
−
* Updated: [[#util:replicate|util:replicate]]: Third argument added.
+
* 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: {{Code|util:replicate}}: Third argument added.
  
 
;Version 9.4
 
;Version 9.4
−
* Added: [[#util:root|util:root]]
+
* Added: {{Function||util:root}}
  
 
;Version 9.3
 
;Version 9.3
−
* Added: [[#util:ddo|util:ddo]]
+
* Added: {{Function||util:ddo}}
  
 
;Version 9.2
 
;Version 9.2
−
* Added: [[#util:chars|util:chars]], [[#util:init|util:init]]
+
* Added: {{Code|util:chars}}, {{Code|util:init}}
−
* Updated: [[#util:item|util:item]], [[#util:last|util:last]], [[#util:range|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: [[#util:if|util:if]], [[#util:or|util:or]]
+
* Added: {{Function||util:if}}, {{Code|util:or}}
  
 
;Version 9.0
 
;Version 9.0
−
* Added: [[#util:replicate|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"