Extend the endpoint to also process queries with other SPARQL constructs

[JackJackie]

We need to add handling of the following constructs:

• Values
• Limit
• Union
• Filter exists
• Filter not exists
• Bind
• Nested selects
• ....

[bnouwt]

Possible example query that in a (far) future could be supported:

select distinct ?s ?p ?o { 
		{<https://tno.nl/data/MUM-T-3-radio> ?p ?o} 
		UNION 
		{<https://tno.nl/data/MUM-T-3-radio> ?p1 ?s . FILTER(isBlank(?s)) . ?s ?p ?o} 
		UNION 
		{<https://tno.nl/data/MUM-T-3-radio> ?p1 ?s1 .  FILTER(isBlank(?s1)) . ?s1 ?p2 ?s . FILTER(isBlank(?s)) . ?s ?p ?o}
		UNION 
		{<https://tno.nl/data/MUM-T-3-radio> ?p1 ?s1 .  FILTER(isBlank(?s1)) . ?s1 ?p2 ?s2 . FILTER(isBlank(?s2)) . ?s2 ?p3 ?s . FILTER(isBlank(?s)) . ?s ?p ?o}		
} LIMIT 10000

This query is generated by LodView when requesting more info about a particular resource. In this case: /data/MUM-T-3-radio.

[bnouwt]

UNION incoming! 🚀 😉