subject_fragments.rb

module RDF
  class SubjectFragments < RDF::Repository
    attr_reader :client
    def initialize(url)
      @client = Client.new(url)
    end

    def query_pattern(pattern, options = {}, &block)
      pattern = pattern.dup
      pattern.subject   ||= RDF::Query::Variable.new
      pattern.predicate ||= RDF::Query::Variable.new
      pattern.object    ||= RDF::Query::Variable.new
      pattern.initialize!
      query = Query.new(pattern)

      if block_given?
        client.query(query).each_statement(&block)
      else
        raise "Not Implemented"
      end
    end

    class Client
      def initialize(base_url)
        @base_url = base_url
      end

      def query(query)
        resource_uri = query.pattern.subject
        url = @base_url + resource_uri.to_s + "?format=ttl"
        RDF::Graph.load(resource_uri)
      end
    end

    class Query
      attr_reader :pattern
      def initialize(pattern)
        @pattern = pattern
      end
    end
  end
end