Contents

module RDF::Normalize
  ##
  # A RDF Graph normalization serialiser.
  #
  # Normalizes the enumerated statements into normal form in the form of N-Quads.
  #
  # @author [Gregg Kellogg](http://kellogg-assoc.com/)
  class Writer < RDF::NQuads::Writer
    format RDF::Normalize::Format

    # @attr_accessor [RDF::Repository] Repository of statements to serialized
    attr_accessor :repo

    ##
    # Initializes the writer instance.
    #
    # @param  [IO, File] output
    #   the output stream
    # @param  [Hash{Symbol => Object}] options
    #   any additional options
    # @yield  [writer] `self`
    # @yieldparam  [RDF::Writer] writer
    # @yieldreturn [void]
    # @yield  [writer]
    # @yieldparam [RDF::Writer] writer
    def initialize(output = $stdout, **options, &block)
      super do
        @repo = RDF::Repository.new
        if block_given?
          case block.arity
            when 0 then instance_eval(&block)
            else block.call(self)
          end
        end
      end
    end


    ##
    # Adds statements to the repository to be serialized in epilogue.
    #
    # @param  [RDF::Resource] subject
    # @param  [RDF::URI]      predicate
    # @param  [RDF::Value]    object
    # @param  [RDF::Resource] graph_name
    # @return [void]
    def write_quad(subject, predicate, object, graph_name)
      @repo.insert(RDF::Statement(subject, predicate, object, graph_name: graph_name))
    end

    ##
    # Outputs the Graph representation of all stored triples.
    #
    # @return [void]
    def write_epilogue
      statements = RDF::Normalize.new(@repo, **@options).
        statements.
        reject(&:variable?).
        map {|s| format_statement(s)}.
        sort.
        each do |line|
          puts line
        end
      super
    end

    protected

    ##
    # Insert an Enumerable
    #
    # @param  [RDF::Enumerable] graph
    # @return [void]
    def insert_statements(enumerable)
      @repo = enumerable
    end
  end
end

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
rdf-normalize-0.4.0	lib/rdf/normalize/writer.rb