A proposed DSL syntax for SPARQL 1.1 VALUES

sparql_values.rb

it "should support VALUES" do
  # should support single value construct (less verbose form)
  expect(subject.select
                .where([:s, RDF::URI('http://purl.org/dc/terms/title'), :title])
                .values([:title], ["This title", "Another title"]).to_s)
                .to eq "SELECT * WHERE { ?s <http://purl.org/dc/terms/title> ?o . VALUES ?title { 'This title' 'Another title' } }"
  
  # should support single value construct (general form)
  expect(subject.select
                .where([:s, RDF::URI('http://purl.org/dc/terms/title'), :title])
                .values([:title], ["This title", "Another title"]).to_s)
                .to eq "SELECT * WHERE { ?s <http://purl.org/dc/terms/title> ?o . VALUES (?title) { ('This title') ('Another title') } }"

  # should support multiple values
  expect(subject.select
                .where([:s, RDF::URI('http://purl.org/dc/terms/title'), :title], [:s, RDF.type, :type])
                .values([:type, :title], [RDF::URI('http://pcdm.org/models#Object'), "This title"], [RDF::URI('http://pcdm.org/models#Collection', 'Another title']).to_s)
                .to eq "SELECT * WHERE { ?s <http://purl.org/dc/terms/title> ?o . ?s a ?type . VALUES (?type ?title) { (<http://pcdm.org/models#Object> 'This title') (<http://pcdm.org/models#Collection> 'Another title' } }"

  # should support UNDEF for any value
  expect(subject.select
                .where([:s, RDF::URI('http://purl.org/dc/terms/title'), :title], [:s, RDF.type, :type])
                .values([:type, :title], [UNDEF, "This title"], [RDF::URI('http://pcdm.org/models#Collection'), UNDEF]).to_s)
                .to eq "SELECT * WHERE { ?s <http://purl.org/dc/terms/title> ?o . ?s a ?type . VALUES (?type ?title) { (UNDEF 'This title') (<http://pcdm.org/models#Collection> UNDEF) } }"
end

re: ruby-rdf/sparql-client#37

Questions/thoughts:

• While #values matches the spec, it's so overloaded I'm wary of using it in this context. Curious what you think. Could be something more verbose, like #inline_values, #inline_data or ...
• VALUES supports a few different syntax options for a VALUES query with a single value. The first two examples show both forms. Should the single value use the general form as well?
• VALUES can also iterate over the results: SELECT * WHERE { ?s <http://purl.org/dc/terms/title> ?o . } } VALUES (?title) { ('This title') ('Another title') Still thinking about how best to make this distinction in the DSL.