Re: [xml-dev] XPath 3.1 introduction ?

[Dave Pawson <davep@dpawson.co.uk>]

https://www.pluralsight.com/authors/dimitre-novatchev  is the only
comprehensive one I've seen.
Dimitre certainly knows his stuff.

HTH

On 22 June 2016 at 10:43,  <cmarchand@oxiane.com> wrote:
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> Thanks Ghislain ! This is very clear an understandable !
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> In fact, I need also an introduction to XPath 3.0 ...
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> Best regards,
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> Christophe
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> Le 2016-06-22 11:35, Ghislain Fourny a écrit :
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> Hi Christophe
>
> The most prominent add to XPath 3.1 is maps and arrays.
>
> Here's a very abstract overview (which of course misses plenty of smaller
> details). It also applies to XQuery 3.1, which supports them as well.
>
> In short:
> ========
> - Items in sequences can now also be maps or arrays.
> - Maps are associative arrays. Keys are any atomic value. Values are any
> sequences of items (including arrays and maps, so they can nest).
> - Arrays are ordered lists of values. A values is any sequence of items
> (including arrays and maps, so they can nest).
> - Values put into maps and arrays are *not* copied, so you can use maps,
> say, for indexing. This is different from XML node constructors.
>
> To build them:
> ========
> - One syntax for objects, looking a bit like JSON but more generic (since
> you can of course nest expressions) and with a keyword "map", like node
> constructors:
>
> map { "foo" : "bar", "bar" : (1, 2, 3) }
>
> - Two syntaxes for arrays:
>
> Syntax 1 similar to that of maps, with an "array" keyword. It simply takes
> the sequence and each item in it becomes a value of the array (So you can't
> construct arrays with sequences of more than one item with this one):
> array { 1, (2, 3, 4), (), 5 }
> creates an array with 5 values, 1, 2, 3, 4 and 5.
>
> Syntax 2 similar to JSON, but it's comma-sensitive in the sense that they
> delimit the values (so it's not a comma expression inside: the commas are
> part of the constructor)
> [ 1, 2, 3, 4, (), (5, 6) ]
> creates an array with 5 values : 1, 2, 3, 4, the empty sequence, and the
> sequence (5,6)
>
> Navigation:
> ========
> Alternative 1: Use maps and arrays as function items:
> let $map := map { "foo" : "bar" }
> return $map("foo")
>
> let $array := array { 1, 2, 3 }
> return $array(2)
>
> Alternative 2: Use the ? operator (for NCNames and integers):
> let $map := map { "foo" : "bar" }
> return $map?foo
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> let $array := array { 1, 2, 3 }
> return $array?2
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> The ? operator works with wildcards to "unbox" arrays or maps to a sequence:
> let $array := array { 1, 2, 3 }
> return $array?*
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> (it also exists as a unary operator, which implicitly assumes the context
> item on the left-hand-side)
>
> Functions:
> ========
> There are plenty of new functions for maps and arrays documented here:
> https://www.w3.org/TR/xpath-functions-31/#maps-and-arrays
>
> Types:
> =======
> There are item type notations such as map(*), map(xs:integer, node()),
> array(xs:integer), array(*), etc.
>
> I hope it helps you get started!
>
> Feel free to correct me if I got anything wrong in the above.
>
> Kind regards,
> Ghislain
>
>