gistfile1.rb

# Monkey-patching sparql-client to add count support
module SPARQL; class Client

  class Query < RDF::Query

    def self.count(*variables)
      options = variables.last.is_a?(Hash) ? variables.pop : {}
      unless variables.size == 1 and variables.first.is_a?(Symbol)
        raise Exception.new "Only one symbol must be provided for count"
      end
      self.new(:select, options).select(:count => variables.first)
    end

  end

  def count(*args)
    call_query_method(:count, *args)
  end

end; end

class RDF::Query
  class Variable
    def initialize(name = nil, value = nil)
      @count = false
      if name.is_a?(Hash) and name.has_key?(:count)
        @count = true
        name = name[:count]
      end
      @name = (name || "g#{__id__.to_i.abs}").to_sym
      @value = value
    end
    def count?
      @count
    end
    def to_s
      prefix = distinguished? ? '?' : "??"
      var_s = "#{prefix}#{name}"
      var_s =  "(COUNT(#{var_s}) AS ?count)" if count?
      unbound? ? var_s : "#{var_s}=#{value}"
    end
  end
end