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module SPARQL; module Algebra
class Operator
##
# The SPARQL `datatype` operator.
#
# [121] BuiltInCall ::= ... | 'DATATYPE' '(' Expression ')'
#
# @example 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 ) .
# }
#
# @example 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 https://www.w3.org/TR/sparql11-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, **options)
case literal
when RDF::Literal then literal.datatype
else raise TypeError, "expected an RDF::Literal, but got #{literal.inspect}"
end
end
##
#
# Returns a partial SPARQL grammar for this operator.
#
# @return [String]
def to_sparql(**options)
"DATATYPE(#{operands.last.to_sparql(**options)})"
end
end # Datatype
end # Operator
end; end # SPARQL::Algebra
Version data entries
8 entries across 8 versions & 1 rubygems