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Posted to dev@jena.apache.org by Laurent Pellegrino <la...@gmail.com> on 2012/07/10 16:58:11 UTC
Query manipulation and serialization questions
Hello,
I am manipulating Query objects and I was wondering if there is an
utility class that transforms directly a SortCondition (retrieved
through Query#getOrderBy()) to its associated Op operator? Same
question for ElementFilter?
Is there something similar to Transformers (provided for algebra
transformation) but for Elements?
Finally, is there a class that can serialize/deserialize SortCondition
and ElementFilter objects? Otherwise, if I switch to the algebra, is
there a class that can serialize/deserialize any Op?
Kind Regards,
Laurent
Re: Query manipulation and serialization questions
Posted by Laurent Pellegrino <la...@gmail.com>.
> To and from a Query oor to and from a string?
The former, to and from a Query (or an object retrieved from a Query).
Thank you Andy.
Laurent
On Tue, Jul 10, 2012 at 10:26 PM, Andy Seaborne <an...@apache.org> wrote:
> On 10/07/12 15:58, Laurent Pellegrino wrote:
>>
>> Hello,
>>
>> I am manipulating Query objects and I was wondering if there is an
>> utility class that transforms directly a SortCondition (retrieved
>> through Query#getOrderBy()) to its associated Op operator? Same
>> question for ElementFilter?
>
>
> Expressions don't need translation - the AST produced by the parser (the E_*
> classes) is the algebra form.
>
> See
>
> AlgebraGenerator.compileModifiers
>
>
>> Is there something similar to Transformers (provided for algebra
>> transformation) but for Elements?
>
>
> There is a visitor pattern but not a transformation pattern on top of that.
>
>
>>
>> Finally, is there a class that can serialize/deserialize SortCondition
>> and ElementFilter objects?
>
>
>
>> Otherwise, if I switch to the algebra, is
>> there a class that can serialize/deserialize any Op?
>
>
> To and from a Query oor to and from a string?
>
> == serialize/dersialize an Op
> as an algebra syntax:
>
> SSE.write
> SSE.parseOp
>
>
> == Query
>
> OpAsQuery does a fairly good job.
>
> 1/ It is possible to write algebra expressions for which there is no query
> 2/ OpAsQuery isn't perfect.
>
>>
>> Kind Regards,
>
>
>
>>
>> Laurent
>>
>
>
Re: Query manipulation and serialization questions
Posted by Andy Seaborne <an...@apache.org>.
On 10/07/12 15:58, Laurent Pellegrino wrote:
> Hello,
>
> I am manipulating Query objects and I was wondering if there is an
> utility class that transforms directly a SortCondition (retrieved
> through Query#getOrderBy()) to its associated Op operator? Same
> question for ElementFilter?
Expressions don't need translation - the AST produced by the parser (the
E_* classes) is the algebra form.
See
AlgebraGenerator.compileModifiers
> Is there something similar to Transformers (provided for algebra
> transformation) but for Elements?
There is a visitor pattern but not a transformation pattern on top of that.
>
> Finally, is there a class that can serialize/deserialize SortCondition
> and ElementFilter objects?
> Otherwise, if I switch to the algebra, is
> there a class that can serialize/deserialize any Op?
To and from a Query oor to and from a string?
== serialize/dersialize an Op
as an algebra syntax:
SSE.write
SSE.parseOp
== Query
OpAsQuery does a fairly good job.
1/ It is possible to write algebra expressions for which there is no query
2/ OpAsQuery isn't perfect.
>
> Kind Regards,
>
> Laurent
>