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

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

Overview

The SPARQL datatype operator.

[121] BuiltInCall ::= ... | 'DATATYPE' '(' Expression ')'

Examples:

SPARQL Grammar

PREFIX  xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX  : <http://example.org/things#>
SELECT  ?x ?v
WHERE
    { ?x :p ?v . 
      FILTER ( datatype(?v) = xsd:double ) .
    }

SSE

(prefix ((xsd: <http://www.w3.org/2001/XMLSchema#>)
         (: <http://example.org/things#>))
 (project (?x ?v)
  (filter (= (datatype ?v) xsd:double)
   (bgp (triple ?x :p ?v)))))

See Also:

Constant Summary collapse

NAME = 
:datatype

Instance Method Summary collapse

Methods included from Evaluatable

#evaluate, #memoize, #replace_aggregate!, #replace_vars!

Instance Method Details

#apply(literal, **options) ⇒ 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 40

def apply(literal, **options)
  case literal
    when RDF::Literal then literal.datatype
    else raise TypeError, "expected an RDF::Literal, but got #{literal.inspect}"
  end
end

#to_sparql(**options) ⇒ String

Returns a partial SPARQL grammar for this operator.

Returns:

  • (String) 


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# File 'lib/sparql/algebra/operator/datatype.rb', line 52

def to_sparql(**options)
  "DATATYPE(#{operands.last.to_sparql(**options)})"
end