Sha256: c2ba6e9e620aa0d0d390827eca311bad15f21a39ce3982476ef30144bccdb8eb
Contents?: true
Size: 1.65 KB
Versions: 7
Compression:
Stored size: 1.65 KB
Contents
module SPARQL; module Algebra
class Operator
##
# The SPARQL `bound` operator.
#
# @example
# (prefix ((: <http://example.org/ns#>))
# (project (?a ?c)
# (filter (! (bound ?e))
# (leftjoin
# (bgp (triple ?a :b ?c))
# (bgp (triple ?c :d ?e))))))
#
# @see https://www.w3.org/TR/sparql11-query/#func-bound
class Bound < Operator::Unary
include Evaluatable
NAME = :bound
##
# Initializes a new operator instance.
#
# @param [RDF::Query::Variable] var
# a variable
# @param [Hash{Symbol => Object}] options
# any additional options (see {Operator#initialize})
# @raise [TypeError] if any operand is invalid
def initialize(var, **options)
super
end
##
# Returns `true` if `var` is bound to a value. Returns false otherwise. Variables with the value NaN or INF are considered bound.
#
# @param [RDF::Query::Solution] bindings
# a query solution containing zero or more variable bindings
# @param [Hash{Symbol => Object}] options ({})
# options passed from query
# @return [RDF::Literal::Boolean] `true` or `false`
# @raise [TypeError] if the operand is not a variable
def evaluate(bindings, **options)
case var = operand
when Variable
bindings.respond_to?(:bound?) && bindings.bound?(var) ?
RDF::Literal::TRUE : RDF::Literal::FALSE
else raise TypeError, "expected an RDF::Query::Variable, but got #{var.inspect}"
end
end
end # Bound
end # Operator
end; end # SPARQL::Algebra
Version data entries
7 entries across 7 versions & 1 rubygems