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Contents
module SPARQL; module Algebra
class Operator
##
# The SPARQL `min` set function.
#
# @example
# (prefix ((: <http://www.example.org/>))
# (project (?max)
# (extend ((?min ?.0))
# (group () ((?.0 (min ?o)))
# (bgp (triple ?s ?p ?o))))))
#
# @see http://www.w3.org/TR/sparql11-query/#defn_aggMin
class Min < Operator::Unary
include Aggregate
NAME = :min
##
# Min is a SPARQL set function that return the minimum value from a group respectively.
#
# It makes use of the SPARQL ORDER BY ordering definition, to allow ordering over arbitrarily typed expressions.
#
# @param [Enumerable<Array<RDF::Term>>] enum
# enum of evaluated operand
# @return [RDF::Literal] The maximum value of the terms
def apply(enum)
if enum.empty?
raise TypeError, "Minumuim of an empty multiset"
elsif enum.flatten.all? {|n| n.literal?}
RDF::Literal(enum.flatten.min)
else
raise TypeError, "Minumuim of non-literals: #{enum.flatten}"
end
end
end # Min
end # Operator
end; end # SPARQL::Algebra
Version data entries
25 entries across 25 versions & 1 rubygems