Re: [XQuery 3.1] focus used in evaluation of keyspecifier in lookup

The keyspecifier in a lookup expression can be a parenthesized
expression and so it can be focus dependent. Such parenthesized
expressions are on the same level in the parent postfix expression as
function call parameters (argument list) which are evaluated using the
parent postfix expressions original focus (although this could be also
added to the spec as currently is not explicitly stated). So from that
perspective it makes indeed sense to use the same focus for the
keyspecifier - ie the parent postfix expressions focus. But then one
will have to change the current postfix lookup definition (3.10.3.2.)
which is done via the semantic equivalence of E?S and E! ?S. as the
simple map operator(!) does create an inner focus for the evaluation
of its rhs (3.18.)

Best regards,
Botond Biró


On Fri, Dec 5, 2014 at 8:01 PM, Michael Kay <mike@saxonica.com> wrote:
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> On 5 Dec 2014, at 15:18, Biró D. Botond <botond23@gmail.com> wrote:
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>> Dear All,
>>
>> Is it expected to evaluate the keyspecifier with a new inner focus?
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> No, it isn't. I can't think of why it would be useful.
>
> Michael Kay
> Saxonica
> mike@saxonica.com
> +44 (0) 118 946 5893
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>>> From semantic equivalance of E?S and E ! ?S one would expect so – in
>> this case I suggest to mention the postfix lookup in the context
>> changing expressions in 2.1.2 Dynamic context – context item
>> definition.
>>
>> Best regards,
>> Botond Biro
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>>
>

Received on Friday, 5 December 2014 20:10:16 UTC