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Contents
module SPARQL; module Algebra
class Operator
##
# The SPARQL GraphPattern `union` operator.
#
# @example
# (prefix ((: <http://example/>))
# (union
# (bgp (triple ?s ?p ?o))
# (graph ?g
# (bgp (triple ?s ?p ?o)))))
#
# @see http://www.w3.org/TR/rdf-sparql-query/#sparqlAlgebra
class Union < Operator::Binary
include Query
NAME = [:union]
##
# Executes each operand with `queryable` and performs the `union` operation
# by creating a new solution set consiting of all solutions from both operands.
#
# @param [RDF::Queryable] queryable
# the graph or repository to query
# @param [Hash{Symbol => Object}] options
# any additional keyword options
# @return [RDF::Query::Solutions]
# the resulting solution sequence
# @see http://www.w3.org/TR/rdf-sparql-query/#sparqlAlgebra
def execute(queryable, options = {})
debug(options) {"Union"}
@solutions = RDF::Query::Solutions.new(operands.inject([]) do |memo, op|
solns = op.execute(queryable, options.merge(:depth => options[:depth].to_i + 1))
debug(options) {"=> (op) #{solns.inspect}"}
memo + solns
end)
debug(options) {"=> #{@solutions.inspect}"}
@solutions
end
##
# Returns an optimized version of this query.
#
# Optimize operands and remove any which are empty.
#
# @return [Union, RDF::Query] `self`
def optimize
ops = operands.map {|o| o.optimize }.select {|o| o.respond_to?(:empty?) && !o.empty?}
@operands = ops
self
end
end # Union
end # Operator
end; end # SPARQL::Algebra
Version data entries
10 entries across 10 versions & 1 rubygems