Returns a map providing access to the index constructed using xsl:key.
key-map($key as xs:string, $doc as document-node(), $min as xs:string?, $max as xs:string?) ➔ map(xs:string, node()*)
The name of the key
The root of the tree
The low end of the required key range
The high end of the required key range
Notes on the Saxon implementation
Available since Saxon 9.5. Applicable to XSLT only. Not available in SaxonCS.
To use this function, it is first necessary to declare a key as a range key, which can be done using a declaration such as:<xsl:key name="k" match="transaction" use="@date" saxon:range-key="yes"/>
The effect of this declaration is that Saxon builds the index underpinning the key
using a Java
TreeMap rather than a
HashMap, making ordered
traversal possible. At present a key can be declared as a range key only if the keys are
of type string (or untypedAtomic), and if the Unicode codepoint collation is used. If
there are several
xsl:key elements with the same name, declaring any one of
them as a range key is sufficient.
The effect of the
saxon:key-map() function is to construct a map
(actually, a wrapper for the underlying index), in which the entries represent the nodes
selected by the
match pattern of the
within the document identified by the
$doc argument. The
$max arguments restrict the map to those entries whose keys lie between
$max values respectively; either argument can be
set to an empty sequence to indicate an open-ended range of key values.
In the resulting map, the function map:keys() is guaranteed to return keys in sorted order. (This does not apply, however, if new maps are constructed from this map by adding or removing entries or combining several maps.)
The resulting map can be used using all the functions available for maps, for example
map:get() to get an entry,
map:keys() to enumerate the key values,
determine if the map is empty, and so on. The maps for several documents can be combined
into a single map using a construct such as:
Note however that the resulting map will not be sorted.