Update grammar for quoted triples and triple functions

[afs]

Part of issue #53 (Incorporate RFD-star CG report)

This is the SPARQL Grammar changes, and only those changes, to replace the table in section 19.8.

This is not directly the content from the CG report because the complete SPARQL grammar in the report has various errors and omissions. The fragment earlier in the report is closer.

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Preview | Diff

[afs]

Online validator: https://www.sparql.org/query-validator.html

Note: this service is to not guaranteed to be available. The service does occasional experience (accidentally) DOS attacks and may become uncontactable. All we can do is wait.

Syntax features illustration:
Query:

PREFIX :        <http://example/>

SELECT ?x (<<?s ?p ?o >> AS ?T) {
    VALUES ?a { <<:s :p :o >> }
    VALUES (?a ?b)  {
        ( <<:s1 :p1 :o1 >>  123 )
        ( 456 <<:s2 :p2 :o2 >> )
    }

     <<?s :p ?o >> :q1 123 ;
                   :q2 [ :r <<?s :p ?o >>  ] .
                   
     <http://example/x> :q <<?s :p ?o >> .

      <<?s :p ?o >> <http://example/p> <<?s :p ?o >> .

     ?s ?p ?o .
     BIND( <<?s ?p ?o >> AS ?qtriple0 )
     BIND( triple(?s , ?p , ?o) AS ?qtriple )
     FILTER( isTriple(?qtriple) )
     FILTER( subject(?qtriple) )
     FILTER( predicate(?qtriple) )
     FILTER( object(?qtriple) )
}

Update:

PREFIX :        <http://example/>

INSERT DATA { <<:s :p :o >> :q 123 . }
;
INSERT { << ?s ?p ?o >> :r "abc" }
WHERE  { ?s ?p ?o }

[hartig]

Online validator: https://www.sparql.org/query-validator.html

Great!!

[afs]

HTML now indented.

The content is ready for review and we can get the grammar so it gets into the WD and also can be used for the rest of #53.

There are some rules that need more layout tuning. This is not new to 1.2 but due to reSpec being narrower than the SPARQL 1.1 doc it stands out more.

[Tpt]

Thank you!

I have tested the grammar as written in this PR with Oxigraph and it seems to work.

Two nitpicks:

• All terminal rule names are now displayed between < and > except IRIREF.
• Would not add QuotedTriple to the GraphTerm rule but to the VarOrTerm rule to keep the GraphTerm rule focused on RDF terms without variables in them. But it's a personal test, please ignore this comment if you feel it's not relevant.

[gkellogg]

Agree that terminals should not be enclosed in angle brackets.

[afs]

All terminal rule names are now displayed between < and > except IRIREF.

Mistake fixed.

[afs]

Would not add QuotedTriple to the GraphTerm rule but to the VarOrTerm rule to keep the GraphTerm rule focused on RDF terms without variables in them.

Yes - and as its now recursive on variables, GraphTerm can be pulled up into VarOrTerm (single use). This makes it more like
DataBlockValue.

[rubensworks]

Online validator: https://www.sparql.org/query-validator.html

@afs I noticed that this query validator doesn't accept update queries (also not regular 1.1 update queries), is this intentional?

[afs]

There is a separate validator: https://www.sparql.org/update-validator.html

Updates are not queries in SPARQL.

[afs]

The force push is a rebase with current main after several other changes to check this PR branch to check before merging.

[gkellogg]

It would be nice to have the raw EBNF used to generate the HTML grammar table somewhere in the repository.

[afs]

https://github.com/apache/jena/tree/main/jena-arq/Grammar

It's managed, and tested, using JavaCC.