Class: SPARQL::Algebra::Operator::Datatype

Inherits:
Unary show all
Includes:
Evaluatable
Defined in:
lib/sparql/algebra/operator/datatype.rb

Overview

The SPARQL datatype operator.

Examples:

(prefix ((xsd: <http://www.w3.org/2001/XMLSchema#>)
         (rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>)
         (: <http://example.org/>))
  (project (?s)
    (filter (= (datatype (xsd:double ?v)) xsd:double)
      (bgp (triple ?s :p ?v)))))

See Also:

Constant Summary

NAME =
:datatype

Constants inherited from Unary

Unary::ARITY

Constants inherited from SPARQL::Algebra::Operator

ARITY

Instance Attribute Summary

Attributes inherited from SPARQL::Algebra::Operator

#operands, #options

Instance Method Summary collapse

Methods included from Evaluatable

#evaluate, #memoize

Methods inherited from Unary

#initialize

Methods inherited from SPARQL::Algebra::Operator

arity, base_uri, #base_uri, base_uri=, #boolean, #constant?, #eql?, #evaluatable?, evaluate, #executable?, for, #initialize, #inspect, #operand, #optimize, prefixes, #prefixes, prefixes=, #to_sse, #to_sxp, #variable?

Methods included from Expression

cast, #constant?, #evaluate, for, new, open, #optimize, parse, #to_sse, #variable?

Constructor Details

This class inherits a constructor from SPARQL::Algebra::Operator::Unary

Instance Method Details

#apply(literal) ⇒ RDF::URI

Returns the datatype IRI of the operand.

If the operand is a simple literal, returns a datatype of xsd:string.

Parameters:

  • literal (RDF::Literal)

    a typed or simple literal

Returns:

  • (RDF::URI)

    the datatype IRI, or xsd:string for simple literals

Raises:

  • (TypeError)

    if the operand is not a typed or simple literal



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# File 'lib/sparql/algebra/operator/datatype.rb', line 30

def apply(literal)
  case literal
    when RDF::Literal then case
      when literal.typed?  then RDF::URI(literal.datatype)
      when literal.simple? then RDF::XSD.string
      else raise TypeError, "expected a typed or simple RDF::Literal, but got #{literal.inspect}"
    end
    else raise TypeError, "expected an RDF::Literal, but got #{literal.inspect}"
  end
end