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module SPARQL; module Algebra
class Operator
##
# The SPARQL `datatype` operator.
#
# @example
# (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 http://www.w3.org/TR/rdf-sparql-query/#func-datatype
class Datatype < Operator::Unary
include Evaluatable
NAME = :datatype
##
# Returns the datatype IRI of the operand.
#
# If the operand is a simple literal, returns a datatype of
# `xsd:string`.
#
# @param [RDF::Literal] literal
# a typed or simple literal
# @return [RDF::URI] the datatype IRI, or `xsd:string` for simple literals
# @raise [TypeError] if the operand is not a typed or simple literal
def apply(literal)
case literal
when RDF::Literal then case
when RDF::VERSION.to_s >= "1.1" then literal.datatype
when literal.simple? then RDF::XSD.string
when literal.datatype == RDF::XSD.string then RDF::XSD.string
when literal.plain? then RDF.langString
else RDF::URI(literal.datatype)
end
else raise TypeError, "expected an RDF::Literal, but got #{literal.inspect}"
end
end
end # Datatype
end # Operator
end; end # SPARQL::Algebra
Version data entries
5 entries across 5 versions & 1 rubygems