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This article is part of the [[XQuery|XQuery Portal]].It summarizes provides a summary of the new most important features of the [httphttps://www.w3.org/TR/xquery-31/ XQuery 3.1] Working Draftthat are already supported by BaseXRecommendation.

==Maps==

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The function corresponding to the map has the signature {{Code|function($key as xs:anyAtomicType) as item()*}}. The expression {{Code|$map($key)}} returns the associated value; the function call {{Code|map:get($map, $key)}} is equivalent. For example, if {{Code|$books-by-isbn}} is a map whose keys are ISBNs and whose associated values are {{Code|book}} elements, then the expression {{Code|$books-by-isbn("0470192747")}} returns the {{Code|book}} element with the given ISBN. The fact that a map is a function item allows it to be passed as an argument to higher[[Higher-order functions Order Functions]] that expect a function item as one of their arguments. As an example, the following query uses the higher-order function {{Code|fn:map($f, $seq)}} to extract all bound values from a map:

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Like all other values, maps are immutable. For example, the <code>[[{{Function|Map Module#map:remove|map:remove]]</code> }} function creates a new map by removing an entry from an existing map, but the existing map is not changed by the operation. Like sequences, maps have no identity. It is meaningful to compare the contents of two maps, but there is no way of asking whether they are "the same map": two maps with the same content are indistinguishable.

==Arrays==

An ''array'' is a function that associates a set of positions, represented as positive integer keys, with values. The first position in an array is associated with the integer {{Code|1}}. The values of an array are called its members. In the type hierarchy, array has a distinct type, which is derived from function. In BaseX, arrays (as well as sequences) are based on an efficient [https://en.wikipedia.org/wiki/Finger_tree Finger Tree] implementation.

<pre classlang="brush:'xquery"'>[], (: empty array :)[ (1, 2) ], (: array with single member :)[ 1 to 2, 3 ] (: array with two members; same as: [ (1, 2), 3 ] :)

<pre classlang="brush:'xquery"'>array { }, (: empty array; same as: array { () } :) array { (1, 2) }, (: array with three two members; same as: array { 1, 2 } :)array { 1 to 2, 3 } (: array with three members; same as: array { 1, 2, 3 } :)

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Like all other values, arrays are immutable. For example, the <code>[[{{Function|Array Module#array:reverse|array:reverse]]</code> }} function creates a new array containing a re-ordering of the members of an existing array, but the existing array is not changed by the operation. Like sequences, arrays have no identity. It is meaningful to compare the contents of two arrays, but there is no way of asking whether they are "the same array": two arrays with the same content are indistinguishable.

===Atomization===

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==Lookup Operator==

The lookup operator provides some syntactic sugar to access values of maps or array members at a specified position. It is introduced by the question mark ({{Code|?}}) and followed by a specifier. The specifier can be:

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$map?('G','B') (: 43. returns the values associated with the key 'G' and 'B' :)

$array?1 (: 32. returns the first value; same as: $array(21) :), $array?(2 to 3) (: 43. returns the second and third values ; same as: (1 to 2 and 3 ) ! $array(.) :)

<pre classlang="brush:'xquery"'>for let $map in maps := (

return $mapmaps[?name = 'Hildur'] ?city

==Arrow Operator==

The arrow operator applies a function to an item. The item is used as the first argument to the function. It is introduced with the characters <code>=></code>, and it is followed by provides a convenient alternative syntax for passing on functions to a value. The expression that precedes the operator will be supplied as first argument of the function to be calledthat follows the arrow. If <code>$iv</code> is an item a value and <code>f()</code> is a function, then <code>$iv =>f()</code> is equivalent to <code>f($iv)</code>, and <code>$iv =>f($j)</code> is equivalent to <code>f($iv, $j)</code>. This is further illustrated by an example:

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==Functions=String Constructor=

The following functions of the string constructor has been inspired by [httphttps://wwwen.w3wikipedia.org/TR/xpath-functions-31wiki/ Here_document here document] literals of the Unix shell and script languages. It allows you to generate strings that contain various characters that would otherwise be interpreted as XQuery 3delimiters.1 Functions and Operators] Working Draft have already been implemented:

* [[Map Module|Map functions]]: <code>map:merge</code>, <code>map:size</code>, <code>map:keys</code>, <code>map:contains</code>, <code>map:get</code>, <code>map:entry</code>, <code>map:put</code>, <code>map:remove</code>, <code>map:The string constructors syntax uses two backticks and a square bracket for-each-entry</code>* [[Array Module|Array functions]]: <code>array:size</code>, <code>array:append</code>, <code>array:subarray</code>, <code>array:remove</code>, <code>array:insert-before</code>, <code>array:head</code>, <code>array:tail</code>, <code>array:reverse</code>, <code>array:join</code>, <code>array:for-each-member</code>, <code>array:filter</code>, <code>array:for-each-pair</code>* <code>fn:contains-token($input as xs:string*, $token as string, $collation as xs:opening and closing a string) as xs:boolean</code>: Checks if the input strings contain a given token.

New signatures <pre lang='xquery'>(: Returns "This is a 'new' & 'flexible' syntax." :)``["This is a 'new' & 'flexible' syntax."]``</pre> XQuery expressions can be embedded via backticks and a curly bracket. The evaluated results will be separated with spaces, and all strings will eventually be concatenated: <pre lang='xquery'>(: Returns »Count 1 2 3, and I will be there.« :)let $c := 1 to 3return ``[»Count `{ $c }`, and I will be there.«]``</pre> =Serialization= Two [[Serialization]] methods have been added to the [https://www.w3.org/TR/xslt-xquery-serialization-31 Serialization spec]: ==Adaptive Serialization== The {{Code|adaptive}} serialization provides an intuitive textual representation for all XDM types, including maps and arrays, functions, attributes, and namespaces. All items will be separated by the value of the {{Code|item-separator}} parameter, which by default is a newline character. It is utilized by the following functions{{Function|Profiling|prof:dump}} and <code>[https://www.w3.org/TR/xpath-functions-31/#func-trace fn:trace]</code>. Example: <pre lang='xquery'>declare option output:method 'adaptive';<element id='id0'/>/@id,xs:token("abc"),map { 'key': 'value' },true#0</pre> Result: <pre lang="xml">id="id0"xs:token("abc"),map { "key": "value"}fn:true#0</pre> ==JSON Serialization== The new {{Code|json}} serialization output method can be used to serialize XQuery maps, arrays, atomic values and empty sequences as JSON.

* <code>fn:tokenize($string as xsThe {{Code|json}} output method has been introduced in BaseX before it was added to the official specification. It complies with the standard serialization rules and, at the same time, preserves the existing semantics:string) as xs:string*</code>: Splits a string at whitespace boundaries.

Items of type The following two queries will both return the JSON snippet <code>xs{ "key":hexBinary</code> and <code>xs:base64Binary"value" }</code> can now be compared against each other. The following queries all yieldl {{Code|true}}:

<pre lang='xquery'>declare option output:method 'json';map { "key": "value" }</pre> <pre lang='xquery'>declare option output:method 'json';<json type='object'> <key>value</key></json></pre> =Functions= The following functions have been added in the [https://www.w3.org/TR/xpath-functions-31/ XQuery 3.1 Functions and Operators] Specification: ==Map Functions== <code>map:merge</code>, <code>map:size</code>, <code>map:keys</code>, <code>map:contains</code>, <code>map:get</code>, <code>map:entry</code>, <code>map:put</code>, <code>map:remove</code>, <code>map:for-each</code> Please check out the [[Map Module]] for more details. ==Array Functions== <code>array:size</code>, <code>array:append</code>, <code>array:subarray</code>, <code>array:remove</code>, <code>array:insert-before</code>, <code>array:head</code>, <code>array:tail</code>, <code>array:reverse</code>, <code>array:join</code>, <code>array:flatten</code>, <code>array:for-each</code>, <code>array:filter</code>, <code>array:fold-left</code>, <code>array:fold-right</code>, <code>array:for-each-pair</code> Please check out the [[Array Module]] for more details. ==JSON Functions== With XQuery 3.1, native support for JSON objects was added. Strings and resources can be parsed to XQuery items and, as [[#JSON Serialization|shown above]], serialized back to their original form. ===fn:parse-json=== <pre>fn:parse-json( $json as xs:string? $options as map(*) := ()) as item()?</pre> Parses the supplied string as JSON text and returns its item representation. The result may be a map, an array, a string, a double, a boolean, or an empty sequence. The allowed options can be looked up in the [https://www.w3.org/TR/xpath-functions-31/#func-parse-json specification]. <pre lang='xquery'>parse-json('{ "name": "john" }') (: yields { "name": "json" } :),parse-json('[ 1, 2, 4, 8, 16]') (: yields [ 1, 2, 4, 8, 16 ] :)</pre> ===fn:json-doc=== <pre>fn:json-doc( $href as xs:string? $options as map(*) := ()) as item()?</pre> Retrieves the text from the specified URI, parses the supplied string as JSON text and returns its item representation (see {{Function||fn:parse-json}} for more details). <pre lang='xquery'>json-doc("http://ip.jsontest.com/")('ip') (: returns your IP address :)</pre> ===fn:json-to-xml=== <pre>fn:json-to-xml( $json as xs:string? $options as map(*) := ()) as document-node()?</pre> Converts a JSON string to an XML node representation. The allowed options can be looked up in the [https://www.w3.org/TR/xpath-functions-31/#func-json-to-xm specification]. <pre lang='xquery'>json-to-xml('{ "message": "world" }') (: result:<map xmlns="http://www.w3.org/2005/xpath-functions"> <string key="message">world</string></map> :)</pre> ===fn:xml-to-json=== <pre>fn:xml-to-json( $node as xs:string? $options as map(*) := ()) as xs:string?</pre> Converts an XML node, whose format conforms to the results created by {{Function||fn:json-to-xml}}, to a JSON string representation. The allowed options can be looked up in the [https://www.w3.org/TR/xpath-functions-31/#func-xml-to-json specification]. <pre lang='xquery'>(: returns "JSON" :)xml-to-json(<string xmlns="http://www.w3.org/2005/xpath-functions">JSON</string>)</pre> ==fn:sort== <pre>fn:sort( $input as item()*, $collation as xs:string? := fn:default-collation(), $key as function(item()) as xs:anyAtomicType* := fn:data#1) as item()*</pre> Returns a new sequence with sorted {{Code|$input}} items, using an optional {{Code|$collation}}. If a {{Code|$key}} function is supplied, it will be applied on all items. The items of the resulting values will be sorted using the semantics of the {{Code|lt}} expression. <pre lang='xquery'>sort(reverse(1 to 3)) (: yields 1, 2, 3 :),reverse(sort(1 to 3)) (: returns the sorted order in descending order :),sort((3,-2,1), (), abs#1) (: yields 1, -2, 3 :),sort((1,2,3), (), function($x) { -$x }) (: yields 3, 2, 1 :),sort((1,'a')) (: yields an error, as strings and integers cannot be compared :)</pre> ==fn:contains-token== <pre>fn:contains-token( $value as xs:string*, $token as xs:string, $collation as xs:string? := fn:default-collation()) as xs:boolean</pre> The supplied strings will be tokenized at whitespace boundaries. The function returns {{Code|true}} if one of the strings equals the supplied token, possibly under the rules of a supplied collation: <pre lang='xquery'>contains-token(('a', 'b c', 'd'), 'c') (: yields true :)<xml class='one two'/>/contains-token(@class, 'one') (: yields true :)</pre> ==fn:parse-ietf-date== <pre>fn:parse-ietf-date( $value as xs:string?) as xs:dateTime?</pre> Parses a string in the IETF format (which is widely used on the Internet) and returns a {{Code|xs:dateTime}} item: <pre lang='xquery'>fn:parse-ietf-date('28-Feb-1984 07:07:07')" (: yields 1984-02-28T07:07:07Z :),fn:parse-ietf-date('Wed, 01 Jun 2001 23:45:54 +02:00')" (: yields 2001-06-01T23:45:54+02:00 :)</pre> ==fn:apply== <pre>fn:apply( $function as function(*), $arguments as array(*)) as item()*</pre> The supplied {{Code|$function}} is invoked with the specified {{Code|$arguments}}. The arity of the function must be the same as the size of the array. Example: <pre lang='xquery'>fn:apply(concat#5, array { 1 to 5 }) (: 12345 :)fn:apply(function($a) { sum($a) }, [ 1 to 5 ]) (: 15 :)fn:apply(count#1, [ 1,2 ]) (: error. the array has two members :)</pre> ==fn:random-number-generator== <pre>fn:random-number-generator( $seed as xs:anyAtomicType? := ()) as map(xs:string, item())</pre> Creates a random number generator, using an optional seed. The returned map contains three entries: * {{Code|number}} is a random double between 0 and 1* {{Code|next}} is a function that returns another random number generator* {{Code|permute}} is a function that returns a random permutation of its argument The returned random generator is ''deterministic'': If the function is called twice with the same arguments and in the same execution scope, it will always return the same result. Example: <pre lang='xquery'>let $rng := fn:random-number-generator()let $number := $rng('number') (: returns a random number :)let $next-rng := $rng('next')() (: returns a new generator :)let $next-number := $next-rng('number') (: returns another random number :)let $permutation := $rng('permute')(1 to 5) (: returns a random permutation of (1,2,3,4,5) :)return ($number, $next-number, $permutation)</pre> ==fn:format-number== The function has been extended to support scientific notation: <pre lang='xquery'>format-number(1984.42, '00.0e0') (: yields 19.8e2 :)</pre> ==fn:tokenize== If no separator is specified as second argument, a string will be tokenized at whitespace boundaries: <pre lang='xquery'>fn:tokenize("brush a b c d") (:yields "a", "b", "c", "d" :)</pre> ==fn:trace== The second argument can now be omitted: <pre lang='xquery'>fn:trace(<xml/>, "Node: ")/node() (: yields the debugging output "Node: <xml/>" :),fn:trace(<xml/>)/node() (: returns the debugging output "<xml/>" :)</pre> ==fn:string-join== The type of the first argument is now <code>xs:anyAtomicType*</code>, and all items will be implicitly cast to strings: <pre lang='xquery'>fn:string-join(1 to 3) (: yields the string "123" :)</pre> ==fn:default-language== Returns the default language used for formatting numbers and dates. BaseX always returns {{Code|en}}. ==Appendix== The three functions <code>fn:transform</code>, <code>fn:load-xquery-module</code> and <code>fn:collation-key</code> may be added in a future version of BaseX as their implementation might require the use of additional external libraries. =Binary Data= Items of type <code>xs:hexBinary</code> and <code>xs:base64Binary</code> can be compared against each other. The following queries all yield {{Code|true}}: <pre lang='xquery'>

=Collations=Pending Features XQuery 3.1 provides a default collation, which allows for a case-insensitive comparison of ASCII characters (<code>A-Z</code> =<code>a-z</code>). This query returns <code>true</code>: <pre lang='xquery'>declare default collation 'http://www.w3.org/2005/xpath-functions/collation/html-ascii-case-insensitive';'HTML' = 'html'</pre> If the [http://site.icu-project.org/download ICU Library] is downloaded and added to the classpath, the full [https://www.w3.org/TR/xpath-functions-31/#uca-collations Unicode Collation Algorithm] features become available in BaseX: <pre lang='xquery'>(: returns 0 (both strings are compared as equal) :)compare('a-b', 'ab', 'http://www.w3.org/2013/collation/UCA?alternate=shifted')</pre> =Enclosed Expressions= ''Enclosed expression'' is the syntactical term for the expressions that are specified inside a function body, try/catch clauses, node constructors and some other expressions. In the following example expressions, its the empty sequence: <pre lang='xquery'>declare function local:x() { () };try { () } catch * { () },element x { () },text { () }</pre>

The features of With XQuery 3.1 are still subject to change, but we are planning the expression can be omitted. The following query is equivalent to add the following enhancements in near futureupper one:

* Support for JSON: <codepre lang='xquery'>fndeclare function local:json-doc</code>, <code>fn:parse-json</code>x() { };try { } catch * New functions: <code>array:fold-left</code>{ }, <code>array:fold-right</code>, <code>fn:collation-key</code>, <code>fn:load-module</code>, <code>fn:parse-ietf-date</code>, <code>fn:transform</code>, <code>map:for-each-entry</code>* Support for scientific notation: <code>format-numberelement x { }text { }</codepre>