Nil prefix and base_uri

[djboardman]

Hi

This maybe just a misunderstanding of mine about prefixes and base URI but...

I can specify base_uri and get what I expected if there are no prefixes at all in the statement:

base_uri = "http://baseuri/"
statement = ":david :place :st-albans"
r = RDF::Turtle::Reader.new(statement,  base_uri: base_uri)

produces the following when I get the statement:

#<RDF::Statement:0x105228c(<http://baseuri/david> <http://baseuri/place> <http://baseuri/st-albans> .)> 

But if I include a prefix in the statement and add a prefixes hash I get an error:

base_uri = "http://baseuri/"
prefixes = {rdf: "http://www.w3.org/1999/02/22-rdf-syntax-ns#"}
statement = ":david rdf:type :homosapien" 
r = RDF::Turtle::Reader.new(statement,  base_uri: base_uri, prefixes: prefixes)

produces the following error when I get the statement:

ERROR [line 1] undefined prefix: {:production=>:pname, :token=>""}: 
FATAL recovery:   iri: []
FATAL recovery:   subject: []
FATAL recovery:   triples: ["."]
FATAL recovery:   statement: ["."]
 => nil 

I can fix this by including a nil prefix

prefixes = {rdf: "http://www.w3.org/1999/02/22-rdf-syntax-ns#", nil => base_uri}
r = RDF::Turtle::Reader.new(statement, base_uri: base_uri, prefixes: prefixes)

which produces:

#<RDF::Statement:0x13a5394(<http://baseuri/david> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://baseuri/homosapien> .)> 

Is this expected behaviour?

Thanks

[gkellogg]

I'm not able to repeat the second case, where prefixes is defined, as errors are only raised when validating. If not validating, the prefixes option is automatically set to {nil => ""}, as this is a common idiom, although it does not create valid RDF unless base_uri is also defined.

The code should merge {nil => ""} into prefixes if it is defined to support this use case.

However, ReaderError is only raised when validating, so neither case would have resulted in an error.