Map Module
This XQuery Module contains functions for manipulating maps, which will officially be 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:
declare variable $week as map(*) := map { 0: "Sonntag", 1: "Montag", 2: "Dienstag", 3: "Mittwoch", 4: "Donnerstag", 5: "Freitag", 6: "Samstag" };
map:contains
Signatures | map:contains($map as map(*), $key as xs:anyAtomicType) as xs:boolean
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Summary | Returns true if the map supplied as $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 $key .
If the supplied key is |
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map:entry
Signatures | map:entry($key as xs:anyAtomicType, $value as item()*) as map(*)
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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 . If the supplied key is xs:untypedAtomic , it is converted to xs:string . If the supplied key is the xs:float or xs:double value NaN , the supplied $map is returned unchanged.
The function map:new(( map:entry("Su", "Sunday"), map:entry("Mo", "Monday"), map:entry("Tu", "Tuesday"), map:entry("We", "Wednesday"), map:entry("Th", "Thursday"), map:entry("Fr", "Friday"), map:entry("Sa", "Saturday") )) Unlike the map:new(for $b in //book return map:entry($b/isbn, $b)) |
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map:get
Signatures | map:get($map as map(*), $key as xs:anyAtomicType) as item()*
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Summary | Returns the value associated with a supplied key in a given map. This function attempts to find an entry within the map supplied as $map that has a key equal to the supplied value of $key . If there is such an entry, it 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 $key . If the supplied key is xs:untypedAtomic , it is converted to xs:string . If the supplied key is the xs:float or xs:double value NaN , the function returns an empty sequence.
A return value of |
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map:keys
Signatures | map:keys($map as map(*)) as xs:anyAtomicType*
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Summary | Returns a sequence containing all the key values present in a map. The function takes any map as its $map argument and returns the keys that are present in the map as a sequence of atomic values, in implementation-dependent order.
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map:new
Signatures | map:new() as map(*) map:new($maps as map(*)*) as map(*)
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Summary | Constructs and returns a new map. The zero-argument form of the function returns an empty map. It is equivalent to calling the one-argument form of the function with an empty sequence as the value of the first argument.
The one-argument form of the function returns a map that is formed by combining the contents of the maps supplied in the
There is no requirement that the supplied input maps should have the same or compatible types. The type of a map (for example |
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map:remove
Signatures | map:remove($map as map(*), $key as xs:anyAtomicType) as map(*) |
Summary | Constructs a new map by removing an entry from an existing map. The entries in the new map correspond to the entries of $map , excluding any entry whose key is equal to $key .
No failure occurs if the input map contains no entry with the supplied key; the input map is returned unchanged |
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map:size
Signatures | map:size($map as map(*)) as xs:integer |
Summary | Returns a the number of entries in the supplied map. The function takes any map as its $map argument and returns the number of entries that are present in the map.
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map:serialize
Signatures | map:serialize($map as map(*)) as xs:string |
Summary | Returns a string representation of the supplied map. The purpose of this function is to get an insight into the structure of a map item. In most cases, it cannot be used for reconstructing the original map. |
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Changelog
- Version 8.0
- Introduction on maps moved to XQuery 3.1.
- Removed: collation support (in accordance with the latest version of the spec).
- 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' })