Difference between revisions of "Map Module"
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Some examples use the ''map'' {{Code|$week}} defined as: | Some examples use the ''map'' {{Code|$week}} defined as: | ||
<pre class="brush:xquery"> | <pre class="brush:xquery"> | ||
− | declare variable $week | + | declare variable $week := map { |
− | 0: " | + | 0: "Sun", 1: "Mon", 2: "Tue", 3: "Wed", 4: "Thu", 5: "Fri", 6: "Sat" |
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
}; | }; | ||
</pre> | </pre> | ||
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<pre class="brush:xquery"> | <pre class="brush:xquery"> | ||
map:merge(( | map:merge(( | ||
− | map:entry(" | + | map:entry("Sun", "Sunday"), |
− | map:entry(" | + | map:entry("Mon", "Monday"), |
− | map:entry(" | + | map:entry("Tue", "Tuesday"), |
− | map:entry(" | + | map:entry("Wed", "Wednesday"), |
− | map:entry(" | + | map:entry("Thu", "Thursday"), |
− | map:entry(" | + | map:entry("Fri", "Friday"), |
− | map:entry(" | + | map:entry("Sat", "Saturday") |
)) | )) | ||
</pre> | </pre> | ||
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| '''Examples''' | | '''Examples''' | ||
| | | | ||
− | * {{Code|map:get($week, 4)}} returns {{Code|" | + | * {{Code|map:get($week, 4)}} returns {{Code|"Thu"}}. |
* {{Code|map:get($week, 9)}} returns {{Code|()}}. ''(When the key is not present, the function returns an empty sequence.).'' | * {{Code|map:get($week, 9)}} returns {{Code|()}}. ''(When the key is not present, the function returns an empty sequence.).'' | ||
* {{Code|map:get(map:entry(7,())), 7)}} returns {{Code|()}}. ''(An empty sequence as the result can also signify that the key is present and the associated value is an empty sequence.).'' | * {{Code|map:get(map:entry(7,())), 7)}} returns {{Code|()}}. ''(An empty sequence as the result can also signify that the key is present and the associated value is an empty sequence.).'' | ||
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* The following function adds a seventh entry to an existing map: | * The following function adds a seventh entry to an existing map: | ||
<pre class="brush:xquery"> | <pre class="brush:xquery"> | ||
− | map:merge(($week, map { 7: " | + | map:merge(($week, map { 7: "---" })) |
</pre> | </pre> | ||
* In the following example, the values of all maps are combined, resulting in a map with a single key (<code>map { "key": (1, 2, 3) }</code>): | * In the following example, the values of all maps are combined, resulting in a map with a single key (<code>map { "key": (1, 2, 3) }</code>): | ||
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| '''Examples''' | | '''Examples''' | ||
| | | | ||
− | * {{Code|map:remove($week, 4)}} creates <code>map { 0: " | + | * {{Code|map:remove($week, 4)}} creates <code>map { 0: "Sun", 1: "Mon", 2: "Tue", 3: "Wed", 5: "Fri", 6: "Sat" }</code>. |
− | * {{Code|map:remove($week, 23)}} creates <code>map { 0: " | + | * {{Code|map:remove($week, 23)}} creates <code>map { 0: "Sun", 1: "Mon", 2: "Tue", 3: "Wed", 4: "Thu", 5: "Fri", 6: "Sat" }</code>. |
|} | |} | ||
Revision as of 14:20, 11 October 2016
This XQuery Module contains functions for manipulating maps, which has 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:
declare variable $week := map { 0: "Sun", 1: "Mon", 2: "Tue", 3: "Wed", 4: "Thu", 5: "Fri", 6: "Sat" };
map:contains
Signatures | map:contains($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 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") )) Unlike the map:merge(for $b in //book return map:entry($b/isbn, $b)) |
Examples | map:entry("M", "Monday") creates map { "M": "Monday" } .
|
map:for-each
Signatures | map:for-each($map as map(*), $fun as function(xs:anyAtomicType, item()*) as item()*) as item()*
|
Summary | Applies a function to every entry of the supplied $map and returns the results as a sequence. The function supplied as $fun takes two arguments. It is called supplying the key of the map entry as the first argument, and the associated value as the second argument.
|
Examples | The following query adds the keys and values of all map entries and returns (3,7) :
map:for-each( map { 1: 2, 3: 4 }, function($a, $b) { $a + $b } ) |
map:get
Signatures | map:get($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 $map and returns the keys that are present in the map as a sequence of atomic values. The order may differ from the order in which entries were inserted in the map.
|
Examples |
|
map:merge
Template:Mark Signature extended with options argument. By default, value of first key is now adopted.
Signatures | map:merge($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 $maps . The maps are combined as follows:
|
Examples |
map:merge(($week, map { 7: "---" }))
map:merge( for $i in 1 to 3 return map { 'key': $i }, map { 'duplicates': 'combine' } ) |
map:put
Signatures | map:put($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, map { $key, $value }))
|
map:remove
Signatures | map:remove($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
- Updated: map:merge signature extended with options argument. By default, value of first key is now adopted.
- 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' })