Class: RDF::Turtle::Writer

Inherits:
Writer show all
Includes:
StreamingWriter, Util::Logger
Defined in:
vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb

Overview

A Turtle serialiser

Note that the natural interface is to write a whole graph at a time. Writing statements or Triples will create a graph to add them to and then serialize the graph.

The writer will add prefix definitions, and use them for creating @prefix definitions, and minting QNames

Examples:

Obtaining a Turtle writer class

RDF::Writer.for(:ttl)         #=> RDF::Turtle::Writer
RDF::Writer.for("etc/test.ttl")
RDF::Writer.for(file_name:       "etc/test.ttl")
RDF::Writer.for(file_extension:  "ttl")
RDF::Writer.for(content_type:    "text/turtle")

Serializing RDF graph into an Turtle file

RDF::Turtle::Writer.open("etc/test.ttl") do |writer|
  writer << graph
end

Serializing RDF statements into an Turtle file

RDF::Turtle::Writer.open("etc/test.ttl") do |writer|
  graph.each_statement do |statement|
    writer << statement
  end
end

Serializing RDF statements into an Turtle string

RDF::Turtle::Writer.buffer do |writer|
  graph.each_statement do |statement|
    writer << statement
  end
end

Serializing RDF statements to a string in streaming mode

RDF::Turtle::Writer.buffer(stream:  true) do |writer|
  graph.each_statement do |statement|
    writer << statement
  end
end

Creating @base and @prefix definitions in output

RDF::Turtle::Writer.buffer(base_uri:  "http://example.com/", prefixes:  {
    nil => "http://example.com/ns#",
    foaf:  "http://xmlns.com/foaf/0.1/"}
) do |writer|
  graph.each_statement do |statement|
    writer << statement
  end
end

Author:

Direct Known Subclasses

RDF::TriG::Writer

Constant Summary

Constants included from Util::Logger

Util::Logger::IOWrapper

Instance Attribute Summary collapse

Attributes inherited from Writer

#options

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Util::Logger

#log_debug, #log_depth, #log_error, #log_fatal, #log_info, #log_recover, #log_recovering?, #log_statistics, #log_warn, #logger

Methods included from StreamingWriter

#stream_epilogue, #stream_prologue, #stream_statement

Methods inherited from Writer

accept?, #base_uri, buffer, #canonicalize?, dump, each, #encoding, #escaped, #flush, for, format, #format_list, #format_term, #node_id, open, #prefix, #prefixes, #prefixes=, #puts, #to_sym, to_sym, #uri_for, #validate?, #write_comment, #write_statement, #write_triples

Methods included from Util::Aliasing::LateBound

#alias_method

Methods included from Writable

#<<, #insert, #insert_graph, #insert_reader, #insert_statement, #insert_statements, #writable?

Methods included from Util::Coercions

#coerce_statements

Constructor Details

#initialize(output = $stdout, **options) {|writer| ... } ⇒ Writer

TODO:

Get version parameter from ACCEPT header parameter

Initializes the Turtle writer instance.

Parameters:

  • output (IO, File) (defaults to: $stdout) —

    the output stream

  • options (Hash{Symbol => Object}) —

    any additional options

Options Hash (**options):

  • :encoding (Encoding) — default: Encoding::UTF_8 —

    the encoding to use on the output stream

  • :canonicalize (Boolean) — default: false —

    whether to canonicalize literals when serializing

  • :prefixes (Hash) — default: Hash.new —

    the prefix mappings to use (not supported by all writers)

  • :base_uri (#to_s) — default: nil —

    the base URI to use when constructing relative URIs

  • :max_depth (Integer) — default: 3 —

    Maximum depth for recursively defining resources, defaults to 3

  • :standard_prefixes (Boolean) — default: false —

    Add standard prefixes to @prefixes, if necessary.

  • :stream (Boolean) — default: false —

    Do not attempt to optimize graph presentation, suitable for streaming large graphs.

  • :default_namespace (String) — default: nil —

    URI to use as default namespace, same as prefixes[nil]

  • :unique_bnodes (Boolean) — default: false —

    Use unique node identifiers, defaults to using the identifier which the node was originall initialized with (if any).

  • :literal_shorthand (Boolean) — default: true —

    Attempt to use Literal shorthands for numbers and boolean values

  • :version (String) — default: "1.2" —

    Emit a specific version of RDF ("1.1', "1.2", or "1.2-basic"")

Yields:

  • (writer) —

    self

  • (writer)

Yield Parameters:

Yield Returns:

  • (void) 


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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 138

def initialize(output = $stdout, **options, &block)
  @graph = RDF::Graph.new
  @uri_to_pname = {}
  @uri_to_prefix = {}
  @version = options[:version]
  options = {literal_shorthand: true}.merge(options)
  super do
    reset
    if block_given?
      case block.arity
        when 0 then instance_eval(&block)
        else block.call(self)
      end
    end
  end
end

Instance Attribute Details

#graph ⇒ Graph

Returns Graph of statements serialized.

Returns:

  • (Graph) —

    Graph of statements serialized



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 64

def graph
  @graph
end

#version ⇒ String

Returns RDF Version of output.

Returns:

  • (String) —

    RDF Version of output



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 67

def version
  @version
end

Class Method Details

.options ⇒ Object

Writer options

See Also:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 72

def self.options
  super + [
    RDF::CLI::Option.new(
      symbol: :max_depth,
      datatype: Integer,
      on: ["--max-depth DEPTH"],
      description: "Maximum depth for recursively defining resources, defaults to 3.") {true},
    RDF::CLI::Option.new(
      symbol: :stream,
      datatype: TrueClass,
      on: ["--stream"],
      description: "Do not attempt to optimize graph presentation, suitable for streaming large graphs.") {true},
    RDF::CLI::Option.new(
      symbol: :default_namespace,
      datatype: RDF::URI,
      on: ["--default-namespace URI", :REQUIRED],
      description: "URI to use as default namespace, same as prefixes.") {|arg| RDF::URI(arg)},
    RDF::CLI::Option.new(
      symbol: :literal_shorthand,
      datatype: FalseClass,
      on: ["--no-literal-shorthand"],
      description: "Do not attempt to use Literal shorthands fo numbers and boolean values.") {false},
    RDF::CLI::Option.new(
      symbol: :version,
      control: :select,
      datatype: %w{1.1 1.2 1.2-basic},
      on: ["--version"],
      description: "RDF Version."),
  ]
end

Instance Method Details

#blankNodePropertyList(resource, position) ⇒ Object (protected)

Represent resource as a blankNodePropertyList



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 603

def blankNodePropertyList(resource, position)
  return false unless blankNodePropertyList?(resource, position)

  log_debug("blankNodePropertyList") {resource.to_ntriples}
  subject_done(resource)
  @output.write(position == :subject ? "\n#{indent} [" : '[')
  num_props = log_depth {predicateObjectList(resource, true)}
  @output.write((num_props > 1 ? "\n#{indent(2)}" : "") + (position == :object ? ']' : '] .'))
  true
end

#blankNodePropertyList?(resource, position) ⇒ Boolean (protected)

Can subject be represented as a blankNodePropertyList?

Returns:

  • (Boolean) 


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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 593

def blankNodePropertyList?(resource, position)
  !resource.statement? && resource.node? &&
    !collection?(resource) &&
    !reifiedTriple?(resource, position) &&
    !in_triple_term?(resource) &&
    (!is_done?(resource) || position == :subject) &&
    ref_count(resource) == (position == :object ? 1 : 0)
end

#bump_reference(resource) ⇒ Integer (protected)

Increase the reference count of this resource

Parameters:

Returns:

  • (Integer) —

    resulting reference count



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 543

def bump_reference(resource)
  @references[resource] = ref_count(resource) + 1
end

#collection(node, position) ⇒ Object (protected) 



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 567

def collection(node, position)
  return false if !collection?(node)
  return false if position == :subject && ref_count(node) > 0
  return false if position == :object && prop_count(node) > 0
  #log_debug("collection") {"#{node.to_ntriples}, #{position}"}

  @output.write("(")
  log_depth do
    list = @lists[node]
    log_debug("collection") {list.inspect}
    subject_done(RDF.nil)
    index = 0
    list.each_statement do |st|
      next unless st.predicate == RDF.first
      log_debug {" list this: #{st.subject} first: #{st.object}[#{position}]"}
      @output.write(" ") if index > 0
      path(st.object, position)
      subject_done(st.subject)
      position = :object
      index += 1
    end
  end
  @output.write(')')
end

#collection?(l) ⇒ Boolean (protected)

Checks if l is a valid RDF list, i.e. no nodes have other properties.

Returns:

  • (Boolean) 


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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 562

def collection?(l)
  #log_debug("collection?") {l.inspect}
  return @lists.key?(l)
end

#format_literal(literal, **options) ⇒ String

Returns the N-Triples representation of a literal.

Parameters:

Returns:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 289

def format_literal(literal, **options)
  case literal
  when RDF::Literal
    case @options[:literal_shorthand] && literal.valid? ? literal.datatype : false
    when RDF::XSD.boolean
      %w(true false).include?(literal.value) ? literal.value : literal.canonicalize.to_s
    when RDF::XSD.integer
      literal.value.match?(/^[\+\-]?\d+$/) && !canonicalize? ? literal.value : literal.canonicalize.to_s
    when RDF::XSD.decimal
      literal.value.match?(/^[\+\-]?\d+\.\d+?$/) && !canonicalize? ?
        literal.value :
        literal.canonicalize.to_s
    when RDF::XSD.double
      in_form = case literal.value
      when /[\+\-]?\d+\.\d*E[\+\-]?\d+$/i then true
      when /[\+\-]?\.\d+E[\+\-]?\d+$/i    then true
      when /[\+\-]?\d+E[\+\-]?\d+$/i      then true
      else false
      end && !canonicalize?

      in_form ? literal.value : literal.canonicalize.to_s.sub('E', 'e').to_s
    else
      text = quoted(literal.value)
      text << "@#{literal.language}" if literal.language?
      text << "--#{literal.direction}" if literal.direction?
      text << "^^#{format_uri(literal.datatype)}" if literal.datatype?
      text
    end
  else
    quoted(literal.to_s)
  end
end

#format_node(node, **options) ⇒ String

Returns the Turtle representation of a blank node.

Parameters:

Returns:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 340

def format_node(node, **options)
  options[:unique_bnodes] ? node.to_unique_base : node.to_base
end

#format_tripleTerm(statement, **options) ⇒ String

Returns a triple term

Parameters:

Returns:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 350

def format_tripleTerm(statement, **options)
  log_debug("tripleTerm") {"#{statement.to_ntriples}"}
  "<<(%s %s %s)>>" % statement.to_a.map { |value| format_term(value, **options) }
end

#format_uri(uri, **options) ⇒ String

Returns the Turtle representation of a URI reference.

Parameters:

Returns:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 328

def format_uri(uri, **options)
  md = uri.relativize(base_uri)
  log_debug("relativize") {"#{uri.to_ntriples} => #{md.inspect}"} if md != uri.to_s
  md != uri.to_s ? "<#{md}>" : (get_pname(uri) || "<#{uri}>")
end

#get_pname(resource) ⇒ String?

Return a PName for the URI, or nil. Adds namespace of PName to defined prefixes

Parameters:

Returns:

  • (String, nil) —

    value to use to identify URI



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 220

def get_pname(resource)
  case resource
  when RDF::Node
    return options[:unique_bnodes] ? resource.to_unique_base : resource.to_base
  when RDF::URI
    uri = resource.to_s
  else
    return nil
  end

  pname = case
  when @uri_to_pname.key?(uri)
    return @uri_to_pname[uri]
  when u = @uri_to_prefix.keys.sort_by {|uu| uu.length}.reverse.detect {|uu| uri.index(uu.to_s) == 0}
    # Use a defined prefix
    prefix = @uri_to_prefix[u]
    unless u.to_s.empty?
      prefix(prefix, u) unless u.to_s.empty?
      log_debug("get_pname") {"add prefix #{prefix.inspect} => #{u}"}
      # Escape suffix, as necessary
      RDF::URI(uri).pname(prefixes: {prefix => u})
    end
  when @options[:standard_prefixes] && vocab = RDF::Vocabulary.each.to_a.detect {|v| uri.index(v.to_uri.to_s) == 0}
    prefix = vocab.__name__.to_s.split('::').last.downcase
    @uri_to_prefix[vocab.to_uri.to_s] = prefix
    prefix(prefix, vocab.to_uri) # Define for output
    log_debug("get_pname") {"add standard prefix #{prefix.inspect} => #{vocab.to_uri}"}
    RDF::URI(uri).pname(prefixes: {prefix => vocab.to_uri})
  else
    nil
  end

  # Make sure pname is a valid pname
  if pname
    md = Terminals::PNAME_LN.match(pname) || Terminals::PNAME_NS.match(pname)
    pname = nil unless md.to_s.length == pname.length
  end

  @uri_to_pname[uri] = pname
end

#in_triple_term?(resource) ⇒ Boolean (protected)

Resource is used within a triple term

Returns:

  • (Boolean) 


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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 557

def in_triple_term?(resource)
  @in_triple_term.key?(resource)
end

#indent(modifier = 0) ⇒ String (protected)

Returns indent string multiplied by the depth

Parameters:

  • modifier (Integer) (defaults to: 0) —

    Increase depth by specified amount

Returns:

  • (String) —

    A number of spaces, depending on current depth



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 495

def indent(modifier = 0)
  " " * (@options.fetch(:log_depth, log_depth) * 2 + modifier)
end

#is_done?(subject) ⇒ Boolean (protected)

Returns:

  • (Boolean) 


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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 547

def is_done?(subject)
  @serialized.include?(subject)
end

#objectList(subject, predicate, objects) ⇒ Object (protected)

Render an objectList having a common subject and predicate



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 685

def objectList(subject, predicate, objects)
  log_debug("objectList") {objects.inspect}
  return if objects.empty?

  objects.each_with_index do |obj, i|
    if i > 0 && blankNodePropertyList?(obj, :object)
      @output.write ", "
    elsif i > 0
      @output.write ",\n#{indent(4)}"
    end
    path(obj, :object)

    # If there is a reifier for this statement, write that out
    tt = RDF::Statement(subject, predicate, obj)
    reifs = @reification.select {|k, v| v.include?(tt)}.keys
    reifs.each do |reif|
      @as_reifiedTriple[reif] = true
      if reif.iri? || ref_count(reif) > 0
        @output.write ' ~ '
        p_term(reif, :subject)
      end
      @output.write ' {| '
      predicateObjectList(reif, true)
      @output.write ' |}'
      subject_done(reif)
    end
  end
end

#order_subjects ⇒ Array<Resource> (protected)

Order subjects for output. Override this to output subjects in another order.

Uses #top_classes and #base_uri.

Returns:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 380

def order_subjects
  seen = {}
  subjects = []

  # Start with base_uri
  if base_uri && @subjects.key?(base_uri)
    subjects << RDF::URI(base_uri)
    seen[RDF::URI(base_uri)] = true
  end

  # Add distinguished classes
  top_classes.each do |class_uri|
    graph.query({predicate:  RDF.type, object:  class_uri}).
      map {|st| st.subject}.
      sort.
      uniq.
      each do |subject|
      log_debug("order_subjects") {subject.to_ntriples}
      subjects << subject
      seen[subject] = true
    end
  end

  # Mark as seen lists that are part of another list
  @lists.values.map(&:statements).
    flatten.each do |st|
      seen[st.object] = true if @lists.key?(st.object)
    end

  # List elements which are bnodes should not be targets for top-level serialization
  list_elements = @lists.values.map(&:to_a).flatten.select(&:node?).compact

  # Sort subjects by resources and statements over bnodes, ref_counts and the subject URI itself
  recursable = (@subjects.keys - list_elements).
    select {|s| !seen.include?(s)}.
    map {|r| [r.node? ? 2 : (r.statement? ? 1 : 0), ref_count(r), r]}.
    sort

  # Sort recursable unto those that are not reifiers and those that are, so that reifieres come last.
  subjects + recursable.map{|r| r.last}.partition {|r| !@reification.key?(r)}.flatten
end

#p_term(resource, position) ⇒ Object (protected)

Default singular resource representation.



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 648

def p_term(resource, position)
  #log_debug("p_term") {"#{resource.to_ntriples}, #{position}"}
  l = if resource == RDF.nil
    "()"
  else
    format_term(resource, **options)
  end
  @output.write(l)
end

#path(resource, position) ⇒ Object (protected)

Represent a resource in subject, predicate or object position. Use either collection, blankNodePropertyList or singular resource notation.

Raises:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 660

def path(resource, position)
  log_debug("path") do
    "#{resource.to_ntriples}, " +
    "pos: #{position}, " +
    "()?: #{collection?(resource)}, " +
    "[]?: #{blankNodePropertyList?(resource, position)}, " +
    "rc: #{ref_count(resource)}"
  end
  raise RDF::WriterError, "Cannot serialize resource '#{resource}'" unless
    collection(resource, position) ||
    reifiedTriple(resource, position) ||
    blankNodePropertyList(resource, position) ||
    p_term(resource, position)
end

#predicate(resource) ⇒ Object (protected) 



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 675

def predicate(resource)
  log_debug("predicate") {resource.to_ntriples}
  if resource == RDF.type
    @output.write("a")
  else
    path(resource, :predicate)
  end
end

#predicate_order ⇒ Array<URI> (protected)

Defines order of predicates to to emit at begninning of a resource description. Defaults to \[rdf:type, rdfs:label, dc:title\]

Returns:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 374

def predicate_order; [RDF.type, RDF::RDFS.label, RDF::URI("http://purl.org/dc/terms/title")]; end

#predicateObjectList(subject, from_bpl = false) ⇒ Integer (protected)

Render a predicateObjectList having a common subject.

Returns:

  • (Integer) —

    the number of properties serialized



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 716

def predicateObjectList(subject, from_bpl = false)
  properties = @subjects.fetch(subject, {})

  prop_list = sort_properties(properties)
  prop_list -= [RDF.first, RDF.rest] if @lists.key?(subject)
  prop_list -= [RDF.reifies] if @as_reifiedTriple.key?(subject)
  log_debug("predicateObjectList") {prop_list.inspect}
  return 0 if prop_list.empty?

  @output.write("\n#{indent(2)}") if properties.keys.length > 1 && from_bpl
  prop_list.each_with_index do |prop, i|
    begin
      @output.write(";\n#{indent(2)}") if i > 0
      predicate(prop)
      @output.write(" ")
      objectList(subject, prop, properties[prop])
    end
  end
  properties.keys.length
end

#preprocess ⇒ Object (protected)

Perform any preprocessing of statements required



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 423

def preprocess
  # Load defined prefixes
  (@options[:prefixes] || {}).each_pair do |k, v|
    @uri_to_prefix[v.to_s] = k
  end

  prefix(nil, @options[:default_namespace]) if @options[:default_namespace]

  case
  when @options[:stream]
  else
    @options[:prefixes] = {}  # Will define actual used when matched

    @graph.each {|statement| preprocess_statement(statement)}
  end
end

#preprocess_statement(statement, as_subject: true) ⇒ Object (protected)

Perform any statement preprocessing required. This is used to perform reference counts and determine required prefixes.

Parameters:

  • statement (Statement)
  • as_subject (Boolean) (defaults to: true) —

    Count as a graph subject



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 444

def preprocess_statement(statement, as_subject: true)
  #log_debug("preprocess") {statement.to_ntriples}
  bump_reference(statement.object)

  # Set RDF version to 1.2, if unset and required.
  if version.nil? && (statement.object.statement? || statement.object.literal? && statement.object.direction?)
    @version = "1.2"
  end

  # TODO: what to do if version is "1.1" or "1.2-basic"?

  # Also count references of triple terms
  preprocess_statement(statement.object, as_subject: false) if statement.object.statement?

  # Count properties of this subject
  if as_subject
    (@subjects[statement.subject] ||= {})[statement.predicate] ||= []
    @subjects[statement.subject][statement.predicate] << statement.object
  else
    # Terms of statement are in triple terms
    statement.to_a.each {|t| @in_triple_term[t] = true}
  end

  # If it fits, allow this to be rendered as a reifiedTriple
  if statement.object.statement? && statement.predicate == RDF.reifies
    @reification[statement.subject] ||= []
    @reification[statement.subject] << statement.object unless
      @reification[statement.subject].include?(statement.object)
  end

  # Collect lists
  if statement.predicate == RDF.first
    l = RDF::List.new(subject: statement.subject, graph: graph)
    @lists[statement.subject] = l if l.valid?
  end

  if statement.object == RDF.nil || statement.subject == RDF.nil
    # Add an entry for the list tail
    @lists[RDF.nil] ||= RDF::List[]
  end

  # Pre-fetch pnames, to fill prefixes
  get_pname(statement.subject)
  get_pname(statement.predicate)
  get_pname(statement.object)
  get_pname(statement.object.datatype) if statement.object.literal? && statement.object.datatype
end

#prop_count(subject) ⇒ Integer (protected)

Return the number of statements having this resource as a subject other than for list properties

Returns:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 528

def prop_count(subject)
  @subjects.fetch(subject, {}).
    reject {|p, o| [RDF.type, RDF.first, RDF.rest, RDF.reifies].include?(p)}.
    values.flatten.length
end

#quoted(string) ⇒ String (protected)

Use single- or multi-line quotes. If literal contains \t, \n, or \r, use a multiline quote, otherwise, use a single-line

Parameters:

Returns:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 516

def quoted(string)
  if string.to_s.match(/[\t\n\r]/)
    string = string.gsub('\\', '\\\\\\\\').gsub('"', '\\"')

    %("""#{string}""")
  else
    "\"#{escaped(string)}\""
  end
end

#ref_count(resource) ⇒ Integer (protected)

Return the number of times this node has been referenced in the object position

Returns:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 536

def ref_count(resource)
  @references.fetch(resource, 0)
end

#reifiedTriple(resource, position) ⇒ Object (protected)

Render a reifiedTriple



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 621

def reifiedTriple(resource, position)
  return false unless reifiedTriple?(resource, position)
  write_id = resource.iri? || ref_count(resource) > 1
  @as_reifiedTriple[resource] = true  # Prevent rdf:reifies from being emitted

  log_debug("reifiedTriple") {resource.to_ntriples}
  subject_done(resource)
  # There may be multiple reifiedTriples using this resource
  @reification[resource].each do |tt|
    @output.write(position == :subject ? "\n#{indent} << " : '<< ')
    reifiedTriple(tt.subject, :object) || p_term(tt.subject, :object)
    @output.write(' ')
    predicate(tt.predicate)
    @output.write(' ')
    reifiedTriple(tt.object, :object) || p_term(tt.object, :object)

    if write_id
      # Only need to output blank node identifiers if they have more than one reference
      @output.write(' ~')
      p_term(resource, :subject)
    end
    @output.write(' >>')
  end
  true
end

#reifiedTriple?(resource, position) ⇒ Boolean (protected)

Is this a reifiedTriple?

Returns:

  • (Boolean) 


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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 615

def reifiedTriple?(resource, position)
  @reification.key?(resource) &&
  (position == :subject ? (prop_count(resource) > 0) : (prop_count(resource) == 0))
end

#reset ⇒ Object (protected)

Reset internal helper instance variables



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 500

def reset
  @lists = {}

  @references = {}
  @serialized = {}
  @subjects = {}
  @reification = {}
  @as_reifiedTriple = {}
  @in_triple_term = {}
end

#sort_properties(properties) ⇒ Array<RDF::URI>

Take a hash from predicate uris to lists of values. Sort the lists of values. Return a sorted list of properties.

Parameters:

Returns:

  • (Array<RDF::URI>) —

    ] Ordered list of properties. Uses predicate_order.



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 265

def sort_properties(properties)
  # Make sorted list of properties
  prop_list = []

  predicate_order.each do |prop|
    next unless properties[prop]
    prop_list << prop
  end

  properties.keys.sort.each do |prop|
    next if prop_list.include?(prop)
    prop_list << prop
  end

  log_debug("sort_properties") {prop_list.join(', ')}
  prop_list
end

#start_document ⇒ Object (protected)

Output @base, @prefix, and @version definitions



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 357

def start_document
  @output.write("#{indent}@version #{version.inspect} .\n") if version
  @output.write("#{indent}@base <#{base_uri}> .\n") unless base_uri.to_s.empty?

  log_debug("start_document") {prefixes.inspect}
  prefixes.keys.sort_by(&:to_s).each do |prefix|
    @output.write("#{indent}@prefix #{prefix}: <#{prefixes[prefix]}> .\n")
  end
end

#statement(subject) ⇒ Object (protected) 



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 747

def statement(subject)
  log_debug("statement") {"#{subject.to_ntriples}, bnodePL?: #{blankNodePropertyList?(subject, :subject)}"}
  subject_done(subject)
  blankNodePropertyList(subject, :subject) || triples(subject)
  @output.puts
end

#subject_done(subject) ⇒ Object (protected)

Mark a subject as done.



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 552

def subject_done(subject)
  @serialized[subject] = true
end

#top_classes ⇒ Array<URI> (protected)

Defines rdf:type of subjects to be emitted at the beginning of the graph. Defaults to rdfs:Class

Returns:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 369

def top_classes; [RDF::RDFS.Class]; end

#triples(subject) ⇒ Object (protected)

Render triples having the same subject using an explicit subject



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 738

def triples(subject)
  @output.write("\n#{indent}")
  path(subject, :subject)
  @output.write(" ")
  num_props = predicateObjectList(subject)
  @output.write("#{num_props > 0 ? ' ' : ''}.")
  true
end

#write_epilogue

This method returns an undefined value.

Outputs the Turtle representation of all stored triples.

See Also:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 187

def write_epilogue
  case
  when @options[:stream]
    stream_epilogue
  else
    @max_depth = @options[:max_depth] || 3

    self.reset

    log_debug("\nserialize") {"graph: #{@graph.size}"}

    preprocess

    start_document

    # Remove lists that are referenced and have non-list properties;
    # these are legal, but can't be serialized as lists
    @lists.reject! do |node, list|
      ref_count(node) > 0 && prop_count(node) > 0
    end

    order_subjects.each do |subject|
      unless is_done?(subject)
        statement(subject)
      end
    end
  end
  super
end

#write_prologue

This method returns an undefined value.

Write out declarations



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 173

def write_prologue
  case
  when @options[:stream]
    stream_prologue
  else
  end
  super
end

#write_triple(subject, predicate, object)

This method returns an undefined value.

Adds a triple to be serialized

Parameters:



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# File 'vendor/bundler/ruby/3.4.0/bundler/gems/rdf-turtle-5818bab04efb/lib/rdf/turtle/writer.rb', line 161

def write_triple(subject, predicate, object)
  statement = RDF::Statement.new(subject, predicate, object)
  if @options[:stream]
    stream_statement(statement)
  else
    @graph.insert(statement)
  end
end