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Re: AW: Missing productions in Core BNF (WD 20 February 2004)?

From: Jerome Simeon <simeon@us.ibm.com>
Date: Thu, 26 Aug 2004 13:20:35 -0400
To: "Bog, Anja" <anja.bog@sap.com>
Cc: "'www-ql@w3.org'" <www-ql@w3.org>
Message-ID: <OF1FD84685.31EA9152-ON85256EFC.005EAE0F-85256EFC.005F410A@us.ibm.com>

I am not sure I understand what you mean by 'sequences of AxisStep'. Do 
you mean
expressions like 'a/b/c' ?

'/' in XPath/XQuery is compiled in the core using a combination of 
iteration using FLWOR
expression and sorting by document order, so it doesn't appear 'as is' 
after normalization
into the XQuery Core.

- Jerome

"Bog, Anja" <anja.bog@sap.com> 
Sent by: www-ql-request@w3.org
08/26/2004 09:13 AM

"'www-ql@w3.org'" <www-ql@w3.org>

AW: Missing productions in Core BNF (WD 20 February 2004)?

Hi everybody,
there's another issue I am wondering about now: If you produce StepExpr 
from ValueExpr
>ValueExpr -> StepExpr -> PrimaryExpr 
how will you produce Sequences of AxisSteps like they are usual for 
-----Ursprüngliche Nachricht-----
Von: www-ql-request@w3.org [mailto:www-ql-request@w3.org] Im Auftrag von 
Jerome Simeon
Gesendet: Mittwoch, 25. August 2004 20:10
An: Sievers, Jan
Cc: www-Ql (www-ql@w3.org)
Betreff: Re: Missing productions in Core BNF (WD 20 February 2004)?

Hi Jan, 

Yes, that is a bug. Good catch. The connection: 

ValueExpr -> PathExpr -> RelativePathExpr -> StepExpr -> FilterExpr -> 

was lost. It should be preserved in the XQuery core through: 

ValueExpr -> StepExpr -> PrimaryExpr 

There is no need for a FilterExpr which would just be a reference to 
PrimaryExpr, but 
we need to introduce back the StepExpr as being the union of AxisStep or 

The corresponding grammar productions should be changed to the following: 

ValueExpr  ::=  ValidateExpr | StepExpr 
StepExpr  ::=  AxisStep | PrimaryExpr 

This will be fixed in the next version of the Formal Semantics document. 

- Jerome 

"Sievers, Jan" <j.sievers@sap.com> 
Sent by: www-ql-request@w3.org 
08/25/2004 11:36 AM 

"www-Ql (www-ql@w3.org)" <www-ql@w3.org> 

Missing productions in Core BNF (WD 20 February 2004)?

Hi everybody,

I am wondering if there are some productions missing in the Core BNF 
defined in "XQuery 1.0 and XPath 2.0 Formal Semantics" (Working Draft 20 
February 2004).

For instance there is no "StepExpr" or "FilterExpr" and the production [53 
(Core)] "PrimaryExpr ::= ..." is never used.

Is this a bug?
Or is there something special about the normalization rules?

Jan Sievers
Received on Thursday, 26 August 2004 17:21:19 UTC

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