Difference between revisions of "Map Module"
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− | This [[Module Library|XQuery Module]] contains functions for manipulating maps. Maps have been introduced with | + | This [[Module Library|XQuery Module]] contains functions for manipulating maps. [[XQuery 3.1#Maps|Maps]] have been introduced with [[XQuery 3.1]]. |
=Conventions= | =Conventions= | ||
Line 8: | Line 8: | ||
Some examples use the ''map'' {{Code|$week}} defined as: | Some examples use the ''map'' {{Code|$week}} defined as: | ||
− | < | + | <syntaxhighlight lang="xquery"> |
declare variable $week := map { | declare variable $week := map { | ||
0: "Sun", 1: "Mon", 2: "Tue", 3: "Wed", 4: "Thu", 5: "Fri", 6: "Sat" | 0: "Sun", 1: "Mon", 2: "Tue", 3: "Wed", 4: "Thu", 5: "Fri", 6: "Sat" | ||
}; | }; | ||
− | </ | + | </syntaxhighlight> |
==map:contains== | ==map:contains== | ||
Line 42: | Line 42: | ||
The function {{Code|map:entry}} is intended primarily for use in conjunction with the function <code>[[#map:merge|map:merge]]</code>. For example, a map containing seven entries may be constructed like this: | The function {{Code|map:entry}} is intended primarily for use in conjunction with the function <code>[[#map:merge|map:merge]]</code>. For example, a map containing seven entries may be constructed like this: | ||
− | < | + | <syntaxhighlight lang="xquery"> |
map:merge(( | map:merge(( | ||
map:entry("Sun", "Sunday"), | map:entry("Sun", "Sunday"), | ||
Line 52: | Line 52: | ||
map:entry("Sat", "Saturday") | map:entry("Sat", "Saturday") | ||
)) | )) | ||
− | </ | + | </syntaxhighlight> |
Unlike the <code>map { ... }</code> expression, this technique can be used to construct a map with a variable number of entries, for example: | Unlike the <code>map { ... }</code> expression, this technique can be used to construct a map with a variable number of entries, for example: | ||
− | < | + | <syntaxhighlight lang="xquery">map:merge(for $b in //book return map:entry($b/isbn, $b))</syntaxhighlight> |
|- | |- | ||
| '''Examples''' | | '''Examples''' | ||
Line 91: | Line 91: | ||
| '''Examples''' | | '''Examples''' | ||
|The following query adds the keys and values of all map entries and returns {{Code|(3,7)}}: | |The following query adds the keys and values of all map entries and returns {{Code|(3,7)}}: | ||
− | < | + | <syntaxhighlight lang="xquery"> |
map:for-each( | map:for-each( | ||
map { 1: 2, 3: 4 }, | map { 1: 2, 3: 4 }, | ||
function($key, $value) { $key + $value } | function($key, $value) { $key + $value } | ||
) | ) | ||
− | </ | + | </syntaxhighlight> |
|} | |} | ||
Line 147: | Line 147: | ||
* {{Code|map:merge((map:entry(0, "no"), map:entry(1, "yes")))}} creates <code>map { 0: "no", 1: "yes" }</code>. | * {{Code|map:merge((map:entry(0, "no"), map:entry(1, "yes")))}} creates <code>map { 0: "no", 1: "yes" }</code>. | ||
* The following function adds a seventh entry to an existing map: | * The following function adds a seventh entry to an existing map: | ||
− | < | + | <syntaxhighlight lang="xquery"> |
map:merge(($week, map { 7: "---" })) | map:merge(($week, map { 7: "---" })) | ||
− | </ | + | </syntaxhighlight> |
* In the following example, the values of all maps are combined, resulting in a map with a single key (<code>map { "key": (1, 2, 3) }</code>): | * In the following example, the values of all maps are combined, resulting in a map with a single key (<code>map { "key": (1, 2, 3) }</code>): | ||
− | < | + | <syntaxhighlight lang="xquery"> |
map:merge( | map:merge( | ||
for $i in 1 to 3 return map { 'key': $i }, | for $i in 1 to 3 return map { 'key': $i }, | ||
map { 'duplicates': 'combine' } | map { 'duplicates': 'combine' } | ||
) | ) | ||
− | </ | + | </syntaxhighlight> |
|} | |} | ||
Revision as of 09:39, 8 April 2020
This XQuery Module contains functions for manipulating maps. Maps have been introduced with XQuery 3.1.
Contents
Conventions
All functions in this module are assigned to the http://www.w3.org/2005/xpath-functions/map
namespace, which is statically bound to the map
prefix.
Functions
Some examples use the map $week
defined as:
<syntaxhighlight lang="xquery">
declare variable $week := map {
0: "Sun", 1: "Mon", 2: "Tue", 3: "Wed", 4: "Thu", 5: "Fri", 6: "Sat"
}; </syntaxhighlight>
map:contains
Signatures | map:contains($map as map(*), $key as xs:anyAtomicType) as xs:boolean
|
Summary | Returns true if the supplied $map contains an entry with a key equal to the supplied value of $key ; otherwise it returns false. No error is raised if the map contains keys that are not comparable with the supplied $key .
If the supplied key is |
Examples |
|
map:entry
Signatures | map:entry($key as xs:anyAtomicType, $value as item()*) as map(*)
|
Summary | Creates a new map containing a single entry. The key of the entry in the new map is $key , and its associated value is $value .
The function <syntaxhighlight lang="xquery"> map:merge(( map:entry("Sun", "Sunday"), map:entry("Mon", "Monday"), map:entry("Tue", "Tuesday"), map:entry("Wed", "Wednesday"), map:entry("Thu", "Thursday"), map:entry("Fri", "Friday"), map:entry("Sat", "Saturday") )) </syntaxhighlight> Unlike the |
Examples | map:entry("M", "Monday") creates map { "M": "Monday" } .
|
map:find
Signatures | map:find($input as item()*, $key as xs:anyAtomicType) as array(*)
|
Summary | Returns all values of maps in the supplied $input with the specified $key . The found values will be returned in an array. Arbitrary input will be processed recursively as follows:
|
Examples |
|
map:for-each
Signatures | map:for-each($map as map(*), $function as function(xs:anyAtomicType, item()*) as item()*) as item()*
|
Summary | Applies the specified $function to every key/value pair of the supplied $map and returns the results as a sequence.
|
Examples | The following query adds the keys and values of all map entries and returns (3,7) :
<syntaxhighlight lang="xquery"> map:for-each( map { 1: 2, 3: 4 }, function($key, $value) { $key + $value } ) </syntaxhighlight> |
map:get
Signatures | map:get($map as map(*), $key as xs:anyAtomicType) as item()*
|
Summary | Returns the value associated with a supplied key in a given map. This function attempts to find an entry within the $map that has a key equal to the supplied value of $key . If there is such an entry, the function returns the associated value; otherwise it returns an empty sequence. No error is raised if the map contains keys that are not comparable with the supplied $key . If the supplied key is xs:untypedAtomic , it is converted to xs:string .
A return value of |
Examples |
|
map:keys
Signatures | map:keys($map as map(*)) as xs:anyAtomicType*
|
Summary | Returns a sequence containing all the key values present in a map. The function takes the supplied $map and returns the keys that are present in the map as a sequence of atomic values. The order may differ from the order in which entries were inserted in the map.
|
Examples |
|
map:merge
Signatures | map:merge($maps as map(*)*) as map(*) map:merge($maps as map(*)*, $options as map(*)) as map(*) |
Summary | Constructs and returns a new map. The map is formed by combining the contents of the supplied $maps . The maps are combined as follows:
|
Examples |
<syntaxhighlight lang="xquery"> map:merge(($week, map { 7: "---" })) </syntaxhighlight>
<syntaxhighlight lang="xquery"> map:merge( for $i in 1 to 3 return map { 'key': $i }, map { 'duplicates': 'combine' } ) </syntaxhighlight> |
map:put
Signatures | map:put($map as map(*), $key as xs:anyAtomicType, $value as item()*) as map(*)
|
Summary | Creates a new map, containing the entries of the supplied $map and a new entry composed by $key and $value . The semantics of this function are equivalent to map:merge((map { $key, $value }, $map))
|
map:remove
Signatures | map:remove($map as map(*), $keys as xs:anyAtomicType*) as map(*) |
Summary | Constructs a new map by removing entries from an existing map. The entries in the new map correspond to the entries of $map , excluding entries supplied via $keys .
No failure occurs if the input map contains no entry with the supplied keys; the input map is returned unchanged. |
Examples |
|
map:size
Signatures | map:size($map as map(*)) as xs:integer |
Summary | Returns a the number of entries in the supplied map. The function takes the supplied $map and returns the number of entries that are present in the map.
|
Examples |
|
Changelog
- Version 8.6
- Added: map:find
- Updated: map:merge: Signature extended with options argument. By default, value of first key is now adopted (instead of last, as in previous versions).
- Version 8.4
- Removed: map:serialize (use fn:serialize instead)
- Version 8.0
- Added: map:for-each, map:merge, map:put
- Removed: support for collations (in accordance with the XQuery 3.1 spec).
- Removed:
map:new
(replaced withmap:merge
) - Updated: aligned with latest specification: compare keys of type
xs:untypedAtomic
asxs:string
instances, storexs:float
orxs:double
valueNaN
. - Introduction on maps is now found in the article on XQuery 3.1.
- Version 7.8
- Updated: map syntax
map { 'key': 'value' }
- Added: map:serialize
- Version 7.7.1
- Updated: alternative map syntax without
map
keyword and:
as key/value delimiter (e.g.:{ 'key': 'value' })