XQuery Recipes - Revision history

CG: Text replacement - "syntaxhighlight" to "pre"

2023-12-01T16:38:48Z

Text replacement - "syntaxhighlight" to "pre"

CG: Text replacement - "" to ""

2023-12-01T16:35:32Z

Text replacement - "</syntaxhighlight>" to "</pre>"

CG: Text replacement - "" to "

2023-12-01T16:29:37Z

Text replacement - "<syntaxhighlight lang="xquery">" to "<pre lang='xquery'>"

CG: Text replacement - "ub-director" to "ubdirector"

2022-07-25T13:59:40Z

Text replacement - "ub-director" to "ubdirector"

CG at 12:23, 27 February 2020

2020-02-27T12:23:27Z

Andy Bunce: update fold-left syntax

2017-07-08T21:41:56Z

update fold-left syntax

CG: Text replace - "\[\[Category:XQuery\]\]" to ""

2016-01-17T13:59:10Z

Text replace - "\[\[Category:XQuery\]\]" to ""

CG: /* Compact XQuery */

2012-11-02T20:34:54Z

Compact XQuery

CG: /* If, then, else */

2012-11-02T20:34:44Z

If, then, else

CG: /* Computed Elements */

2012-11-02T20:32:26Z

Computed Elements

@@ Line 40: / Line 40: @@
 The result is an XML fragment with <code>&lt;element&gt;</code> as root node:
-<syntaxhighlight lang="xml">
+<pre lang="xml">
 <element about="hi">
    <foo>Bar!</foo>
@@ Line 73: / Line 73: @@
 </pre>
 results in
-<syntaxhighlight lang="xml">
+<pre lang="xml">
 <entry id="entry1">
    <entry id="entry2" parentId="entry1">
@@ Line 99: / Line 99: @@
 </pre>
 results in
-<syntaxhighlight lang="xml">
+<pre lang="xml">
 2250433089
 </pre>
@@ Line 112: / Line 112: @@
 The Linux equivalent is
-<syntaxhighlight lang="xml">
+<pre lang="xml">
 find . | grep \.jpg$ | wc -l
 </pre>

@@ Line 13: / Line 13: @@
    (: NEW :) $s ! 'OK'
+)
-</syntaxhighlight>
+</pre>
 In some cases, also the first solution can be written more compact. If we know that our input will always have 0-1 items, we can write <code>if(exists($s))</code>. If our input will never be an empty string, a zero, etc, it’s sufficient to write <code>if($s)</code>.
@@ Line 24: / Line 24: @@
    (: NEW :) ($s, 'default')[1]
+)
-</syntaxhighlight>
+</pre>
 Note that this only works if both of your inputs have zero or one items.
@@ Line 37: / Line 37: @@
    attribute { "about" } { $value }, $contents
+}
-</syntaxhighlight>
+</pre>
 The result is an XML fragment with <code>&lt;element&gt;</code> as root node:
@@ Line 44: / Line 44: @@
    <foo>Bar!</foo>
 </element>
-</syntaxhighlight>
+</pre>
 == Transform List to Tree ==
@@ Line 71: / Line 71: @@
   </entries>
 return local:link($entries/entry, 'entry1')
-</syntaxhighlight>
+</pre>
 results in
 <syntaxhighlight lang="xml">
@@ Line 84: / Line 84: @@
    </entry>
 </entry>
-</syntaxhighlight>
+</pre>
 == IP-Converter ==
@@ Line 97: / Line 97: @@
    function($n, $d) { 256 * $n + $d }
+)
-</syntaxhighlight>
+</pre>
 results in
 <syntaxhighlight lang="xml">
 2250433089
-</syntaxhighlight>
+</pre>
 == Count number of files ==
@@ Line 108: / Line 108: @@
 <pre lang='xquery'>
-basex "count(file:list('.',true(),'*.jpg'))"</syntaxhighlight>
+basex "count(file:list('.',true(),'*.jpg'))"</pre>
 The Linux equivalent is
@@ Line 114: / Line 114: @@
 <syntaxhighlight lang="xml">
 find . | grep \.jpg$ | wc -l
-</syntaxhighlight>
+</pre>

@@ Line 8: / Line 8: @@
 * 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:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 let $s := "X" return (
    (: OLD :) if(count($s) = 1) then 'OK' else (),
@@ Line 19: / Line 19: @@
 * If you want to choose the first non-empty item from two arguments, we can use the position predicate:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 let $s := "X" return (
    (: OLD :) if(exists($s)) then $s else 'default',
@@ Line 30: / Line 30: @@
 == Computed Elements ==
 Returns dynamically named elements:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 let $root := "element"
 let $value := "hi"
@@ Line 49: / Line 49: @@
 This snippet transform a ''flat'' list of elements with <code>parentId</code>-references to a nested list.
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 declare function local:link($entries as node()*, $id as xs:string) {
   let $entry    := $entries[@id eq $id],
@@ Line 90: / Line 90: @@
 This snippet converts an IP address to its numeric representation:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 let $ip := '134.34.226.65'
 return fold-left(
@@ Line 107: / Line 107: @@
 This snippets returns the number of JPG files in a directory and its subdirectories:
-<syntaxhighlight lang="xquery">
+<pre lang='xquery'>
 basex "count(file:list('.',true(),'*.jpg'))"</syntaxhighlight>

@@ Line 105: / Line 105: @@
 == Count number of files ==
-This snippets returns the number of JPG files in a directory and its sub-directories:
+This snippets returns the number of JPG files in a directory and its subdirectories:
 <syntaxhighlight lang="xquery">

@@ Line 8: / Line 8: @@
 * 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">
+<syntaxhighlight lang="xquery">
 let $s := "X" return (
    (: OLD :) if(count($s) = 1) then 'OK' else (),
    (: NEW :) $s ! 'OK'
+)
-</pre>
+</syntaxhighlight>
 In some cases, also the first solution can be written more compact. If we know that our input will always have 0-1 items, we can write <code>if(exists($s))</code>. If our input will never be an empty string, a zero, etc, it’s sufficient to write <code>if($s)</code>.
@@ Line 19: / Line 19: @@
 * If you want to choose the first non-empty item from two arguments, we can use the position predicate:
-<pre class="brush:xquery">
+<syntaxhighlight lang="xquery">
 let $s := "X" return (
    (: OLD :) if(exists($s)) then $s else 'default',
    (: NEW :) ($s, 'default')[1]
+)
-</pre>
+</syntaxhighlight>
 Note that this only works if both of your inputs have zero or one items.
@@ Line 30: / Line 30: @@
 == Computed Elements ==
 Returns dynamically named elements:
-<pre class="brush:xquery">
+<syntaxhighlight lang="xquery">
 let $root := "element"
 let $value := "hi"
@@ Line 37: / Line 37: @@
    attribute { "about" } { $value }, $contents
+}
-</pre>
+</syntaxhighlight>
 The result is an XML fragment with <code>&lt;element&gt;</code> as root node:
-<pre class="brush:xml">
+<syntaxhighlight lang="xml">
 <element about="hi">
    <foo>Bar!</foo>
 </element>
-</pre>
+</syntaxhighlight>
 == Transform List to Tree ==
 This snippet transform a ''flat'' list of elements with <code>parentId</code>-references to a nested list.
-<pre class="brush:xquery">
+<syntaxhighlight lang="xquery">
 declare function local:link($entries as node()*, $id as xs:string) {
   let $entry    := $entries[@id eq $id],
@@ Line 71: / Line 71: @@
   </entries>
 return local:link($entries/entry, 'entry1')
-</pre>
+</syntaxhighlight>
 results in
-<pre class="brush:xml">
+<syntaxhighlight lang="xml">
 <entry id="entry1">
    <entry id="entry2" parentId="entry1">
@@ Line 84: / Line 84: @@
    </entry>
 </entry>
-</pre>
+</syntaxhighlight>
 == IP-Converter ==
@@ Line 90: / Line 90: @@
 This snippet converts an IP address to its numeric representation:
-<pre class="brush:xquery">
+<syntaxhighlight lang="xquery">
 let $ip := '134.34.226.65'
 return fold-left(
@@ Line 97: / Line 97: @@
    function($n, $d) { 256 * $n + $d }
+)
-</pre>
+</syntaxhighlight>
 results in
-<pre class="brush:xml">
+<syntaxhighlight lang="xml">
 2250433089
-</pre>
+</syntaxhighlight>
 == Count number of files ==
@@ Line 107: / Line 107: @@
 This snippets returns the number of JPG files in a directory and its sub-directories:
-<pre class="brush:xquery">
+<syntaxhighlight lang="xquery">
-basex "count(file:list('.',true(),'*.jpg'))"</pre>
+basex "count(file:list('.',true(),'*.jpg'))"</syntaxhighlight>
 The Linux equivalent is
-<pre class="brush:xml">
+<syntaxhighlight lang="xml">
 find . | grep \.jpg$ | wc -l
-</pre>
+</syntaxhighlight>

@@ Line 93: / Line 93: @@
 let $ip := '134.34.226.65'
 return fold-left(
- function($n, $d) { 256 * $n + $d },
+   tokenize($ip, '\.')!xs:integer(.),
 ,
- map(xs:integer#1, tokenize($ip, '\.'))
+  function($n, $d) { 256 * $n + $d }
+)
 </pre>

← Older revision		Revision as of 13:59, 17 January 2016
Line 115:		Line 115:
	find . \| grep \.jpg$ \| wc -l		find . \| grep \.jpg$ \| wc -l
	</pre>		</pre>
−
−	~~[[Category:XQuery]]~~

@@ Line 1: / Line 1: @@
 This page contains code snippets that mainly originate from our [https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk basex-talk] mailing list.
-== Compact XQuery ==
+== Compact Notations ==
 <code>if</code>/<code>not</code>/<code>else</code> constructs can look pretty verbose in XQuery.

← Older revision		Revision as of 20:32, 2 November 2012
Line 1:		Line 1:
	This page contains code snippets that mainly originate from our [https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk basex-talk] mailing list.		This page contains code snippets that mainly originate from our [https://mailman.uni-konstanz.de/mailman/listinfo/basex-talk basex-talk] mailing list.
		+
		+	== If, then, else ==
		+
		+	<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 ==		== Computed Elements ==