Sha256: 7c443e5225eb27ae79222e6862d51e6a3286b043e634e7c086afbf9fba642e27
Contents?: true
Size: 1.95 KB
Versions: 8
Compression:
Stored size: 1.95 KB
Contents
module SPARQL; module Algebra
class Operator
##
# The SPARQL `groupconcat` set function.
#
# @example
# (prefix ((: <http://www.example.org/>))
# (filter (|| (= ?g "1 22") (= ?g "22 1"))
# (project (?g)
# (extend ((?g ?.0))
# (group () ((?.0 (group_concat ?o)))
# (bgp (triple ??0 :p1 ?o)))))))
#
# @see http://www.w3.org/TR/sparql11-query/#defn_aggGroupConcat
class GroupConcat < Operator
include Aggregate
NAME = :group_concat
##
# One or two operands, the second operand, if it exists, is a separator, defaulting to ' '.
#
# @param [Enumerable<RDF::Query::Solution>] solutions ([])
# an enumerable set of query solutions
# @param [Hash{Symbol => Object}] options ({})
# options passed from query
# @return [RDF::Term]
# @raise [TypeError]
# @abstract
def aggregate(solutions = [], options = {})
sep = operands.length == 2 ? operand(0).last : RDF::Literal(' ')
args_enum = solutions.map do |solution|
begin
operands.last.evaluate(solution, options.merge(:depth => options[:depth].to_i + 1))
rescue TypeError
# Ignore errors
nil
end
end
apply(args_enum, sep)
end
##
# GroupConcat is a set function which performs a string concatenation across the values of an expression with a group. The order of the strings is not specified. The separator character used in the concatenation may be given with the scalar argument SEPARATOR.
#
# @param [Enumerable<Array<RDF::Term>>] enum
# enum of evaluated operand
# @return [RDF::Term] An arbitrary term
# @raise [TypeError] If enum is empty
def apply(enum, separator)
RDF::Literal(enum.flatten.map(&:to_s).join(separator.to_s))
end
end # GroupConcat
end # Operator
end; end # SPARQL::Algebra
Version data entries
8 entries across 8 versions & 1 rubygems