The following libraries are written in pure XQuery 3.0:
rbtree.xq - https://github.com/jpcs/rbtree.xq
Functional implementation of a red/black tree (ordered set) that allows
a custom implementation of the comparison function. See the included
"map.xq" for how this can be used to implement a map data structure
using "lt" comparison. Should be easy to implement an alternative map
that allows node keys with a suitable comparison function.
hamt.xq - https://github.com/jpcs/hamt.xq
Functional implementation of a hash array mapped trie (hash set) that
allows a custom hash function and equality function. See the included
"hashmap.xq" for how this can be used to implement a map data structure.
Hope that helps,
John
On 20/11/13 09:43, jean-marc Mercier wrote:
Hello,
I am looking for a map module in XQUERY that would have the following
behavior. Does somebody ever heard of such a module ?
1) The default behavior for inserting keys should be using the
fn:distinct-values(). Note that map module using this mechanism already
exists, see for instance BaseX map:module :
http://docs.basex.org/wiki/Map_Module
2) Accept functions as values. Why this could be useful ? Well, it is
really useful for a lot of things. The first very useful things would be
to use this functionality to bind external parameters to functions.
For instance I could write, (useful for the point 3) below)
declare function
local:is_data1_smaller_than_data2($data1,$data2,$map_bindings){
map:get($map_bindings,"less")($data1,$data2)
};
3) Accept an optional, external ordering predicate. This is actually
what is done with every structured languages. For instance, set in C++
(that are indeed maps) are defined as
template < class T, // set::key_type/value_type
*/_class Compare = less<T>_/*, //
set::key_compare/value_compare
class Alloc = allocator<T> > // set::allocator_type
> class set;
where the ordering predicate is optional (*/_class Compare = less<T>).
_/*Why having an optional ordering predicate could be useful in ?
Because of point 4) below : to use node() as keys in map.
4) Accept node() as keys. This is very useful to a lot of things.
However, it does not exists a canonical ordering for nodes. The function
deep-equal() could be a candidate, but it does not define an ordering,
and performances in insertion using this function would be tremendous.
Thus, to accept node() as keys for maps, one need first to provide an
external ordering predicate for nodes, see point 3) above.
--
John Snelson, Lead Engineer http://twitter.com/jpcs
MarkLogic Corporation http://www.marklogic.com
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