Difference between revisions of "Map Module"
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|map:contains|$map as map(*), $key as xs:anyAtomicType|xs:boolean}} | |{{Func|map:contains|$map as map(*), $key as xs:anyAtomicType|xs:boolean}} | ||
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| '''Summary''' | | '''Summary''' | ||
| Returns true if the supplied {{Code|$map}} contains an entry with a key equal to the supplied value of {{Code|$key}}; otherwise it returns false. No error is raised if the map contains keys that are not comparable with the supplied {{Code|$key}}. | | Returns true if the supplied {{Code|$map}} contains an entry with a key equal to the supplied value of {{Code|$key}}; otherwise it returns false. No error is raised if the map contains keys that are not comparable with the supplied {{Code|$key}}. | ||
If the supplied key is {{Code|xs:untypedAtomic}}, it is compared as an instance of {{Code|xs:string}}. If the supplied key is the {{Code|xs:float}} or {{Code|xs:double}} value {{Code|NaN}}, the function returns true if there is an entry whose key is {{Code|NaN}}, or false otherwise. | If the supplied key is {{Code|xs:untypedAtomic}}, it is compared as an instance of {{Code|xs:string}}. If the supplied key is the {{Code|xs:float}} or {{Code|xs:double}} value {{Code|NaN}}, the function returns true if there is an entry whose key is {{Code|NaN}}, or false otherwise. | ||
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| '''Examples''' | | '''Examples''' | ||
| | | | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|map:entry|$key as xs:anyAtomicType, $value as item()*|map(*)}} | |{{Func|map:entry|$key as xs:anyAtomicType, $value as item()*|map(*)}} | ||
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| '''Summary''' | | '''Summary''' | ||
| Creates a new ''map'' containing a single entry. The key of the entry in the new map is {{Code|$key}}, and its associated value is {{Code|$value}}. | | Creates a new ''map'' containing a single entry. The key of the entry in the new map is {{Code|$key}}, and its associated value is {{Code|$value}}. | ||
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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> | <syntaxhighlight lang="xquery">map:merge(for $b in //book return map:entry($b/isbn, $b))</syntaxhighlight> | ||
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| '''Examples''' | | '''Examples''' | ||
|{{Code|map:entry("M", "Monday")}} creates <code>map { "M": "Monday" }</code>. | |{{Code|map:entry("M", "Monday")}} creates <code>map { "M": "Monday" }</code>. | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|map:find|$input as item()*, $key as xs:anyAtomicType|array(*)}} | |{{Func|map:find|$input as item()*, $key as xs:anyAtomicType|array(*)}} | ||
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| '''Summary''' | | '''Summary''' | ||
| Returns all values of maps in the supplied {{Code|$input}} with the specified {{Code|$key}}. The found values will be returned in an array. Arbitrary input will be processed recursively as follows: | | Returns all values of maps in the supplied {{Code|$input}} with the specified {{Code|$key}}. The found values will be returned in an array. Arbitrary input will be processed recursively as follows: | ||
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* In an array, all array members will be processed as sequence. | * In an array, all array members will be processed as sequence. | ||
* In a map, all entries whose keys match the specified key. Moreover, all values of the map will be processed as sequence. | * In a map, all entries whose keys match the specified key. Moreover, all values of the map will be processed as sequence. | ||
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| '''Examples''' | | '''Examples''' | ||
| | | | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|map:for-each|$map as map(*), $function as function(xs:anyAtomicType, item()*) as item()*|item()*}} | |{{Func|map:for-each|$map as map(*), $function as function(xs:anyAtomicType, item()*) as item()*|item()*}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Applies the specified {{Code|$function}} to every key/value pair of the supplied {{Code|$map}} and returns the results as a sequence. | |Applies the specified {{Code|$function}} to every key/value pair of the supplied {{Code|$map}} and returns the results as a sequence. | ||
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| '''Examples''' | | '''Examples''' | ||
|The following query adds the keys and values of all map entries and returns {{Code|(3,7)}}: | |The following query adds the keys and values of all map entries and returns {{Code|(3,7)}}: | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|map:get|$map as map(*), $key as xs:anyAtomicType|item()*}} | |{{Func|map:get|$map as map(*), $key as xs:anyAtomicType|item()*}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Returns the value associated with a supplied key in a given map. This function attempts to find an entry within the {{Code|$map}} that has a key equal to the supplied value of {{Code|$key}}. If there is such an entry, the function returns the associated value; otherwise it returns an empty sequence. No error is raised if the map contains keys that are not comparable with the supplied {{Code|$key}}. If the supplied key is {{Code|xs:untypedAtomic}}, it is converted to {{Code|xs:string}}. | |Returns the value associated with a supplied key in a given map. This function attempts to find an entry within the {{Code|$map}} that has a key equal to the supplied value of {{Code|$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 {{Code|$key}}. If the supplied key is {{Code|xs:untypedAtomic}}, it is converted to {{Code|xs:string}}. | ||
A return value of {{Code|()}} from {{Code|map:get}} could indicate that the key is present in the map with an associated value of {{Code|()}}, or it could indicate that the key is not present in the map. The two cases can be distinguished by calling {{Code|map:contains}}. | A return value of {{Code|()}} from {{Code|map:get}} could indicate that the key is present in the map with an associated value of {{Code|()}}, or it could indicate that the key is not present in the map. The two cases can be distinguished by calling {{Code|map:contains}}. | ||
Invoking the ''map'' as a function item has the same effect as calling {{Code|get}}: that is, when {{Code|$map}} is a map, the expression {{Code|$map($K)}} is equivalent to {{Code|get($map, $K)}}. Similarly, the expression {{Code|get(get(get($map, 'employee'), 'name'), 'first')}} can be written as {{Code|$map('employee')('name')('first')}}. | Invoking the ''map'' as a function item has the same effect as calling {{Code|get}}: that is, when {{Code|$map}} is a map, the expression {{Code|$map($K)}} is equivalent to {{Code|get($map, $K)}}. Similarly, the expression {{Code|get(get(get($map, 'employee'), 'name'), 'first')}} can be written as {{Code|$map('employee')('name')('first')}}. | ||
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| '''Examples''' | | '''Examples''' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|map:keys|$map as map(*)|xs:anyAtomicType*}} | |{{Func|map:keys|$map as map(*)|xs:anyAtomicType*}} | ||
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| '''Summary''' | | '''Summary''' | ||
|Returns a sequence containing all the key values present in a map. The function takes the supplied {{Code|$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. | |Returns a sequence containing all the key values present in a map. The function takes the supplied {{Code|$map}} and returns the keys that are present in the map as a sequence of atomic values. The order may differ from the order in which entries were inserted in the map. | ||
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| '''Examples''' | | '''Examples''' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|map:merge|$maps as map(*)*|map(*)}}<br/>{{Func|map:merge|$maps as map(*)*, $options as map(*)|map(*)}}<br/> | |{{Func|map:merge|$maps as map(*)*|map(*)}}<br/>{{Func|map:merge|$maps as map(*)*, $options as map(*)|map(*)}}<br/> | ||
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| '''Summary''' | | '''Summary''' | ||
| Constructs and returns a new map. The ''map'' is formed by combining the contents of the supplied {{Code|$maps}}. The maps are combined as follows: | | Constructs and returns a new map. The ''map'' is formed by combining the contents of the supplied {{Code|$maps}}. The maps are combined as follows: | ||
# There is one entry in the new map for each distinct key present in the union of the input maps. | # There is one entry in the new map for each distinct key present in the union of the input maps. | ||
# The {{Code|$options}} argument defines how duplicate keys are handled. Currently, a single option {{Code|duplicates}} exists, and its allowed values are {{Code|use-first}}, {{Code|use-last}}, {{Code|combine}} and {{Code|reject}} (default: {{Code|use-first}}). | # The {{Code|$options}} argument defines how duplicate keys are handled. Currently, a single option {{Code|duplicates}} exists, and its allowed values are {{Code|use-first}}, {{Code|use-last}}, {{Code|combine}} and {{Code|reject}} (default: {{Code|use-first}}). | ||
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| '''Examples''' | | '''Examples''' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|map:put|$map as map(*), $key as xs:anyAtomicType, $value as item()*|map(*)}} | |{{Func|map:put|$map as map(*), $key as xs:anyAtomicType, $value as item()*|map(*)}} | ||
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| '''Summary''' | | '''Summary''' | ||
| Creates a new ''map'', containing the entries of the supplied {{Code|$map}} and a new entry composed by {{Code|$key}} and {{Code|$value}}. The semantics of this function are equivalent to <code>map:merge((map { $key, $value }, $map))</code> | | Creates a new ''map'', containing the entries of the supplied {{Code|$map}} and a new entry composed by {{Code|$key}} and {{Code|$value}}. The semantics of this function are equivalent to <code>map:merge((map { $key, $value }, $map))</code> | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|map:remove|$map as map(*), $keys as xs:anyAtomicType*|map(*)}}<br/> | |{{Func|map:remove|$map as map(*), $keys as xs:anyAtomicType*|map(*)}}<br/> | ||
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| '''Summary''' | | '''Summary''' | ||
| Constructs a new map by removing entries from an existing map. The entries in the new map correspond to the entries of {{Code|$map}}, excluding entries supplied via {{Code|$keys}}. | | Constructs a new map by removing entries from an existing map. The entries in the new map correspond to the entries of {{Code|$map}}, excluding entries supplied via {{Code|$keys}}. | ||
No failure occurs if the input map contains no entry with the supplied keys; the input map is returned unchanged. | No failure occurs if the input map contains no entry with the supplied keys; the input map is returned unchanged. | ||
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| '''Examples''' | | '''Examples''' | ||
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| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
|{{Func|map:size|$map as map(*)|xs:integer}}<br/> | |{{Func|map:size|$map as map(*)|xs:integer}}<br/> | ||
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| '''Summary''' | | '''Summary''' | ||
| Returns a the number of entries in the supplied map. The function takes the supplied {{Code|$map}} and returns the number of entries that are present in the map. | | Returns a the number of entries in the supplied map. The function takes the supplied {{Code|$map}} and returns the number of entries that are present in the map. | ||
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| '''Examples''' | | '''Examples''' | ||
| | | |
Revision as of 14:19, 20 July 2022
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' })