Class: RdfContext::TurtleSerializer

Inherits:
RecursiveSerializer show all
Defined in:
lib/rdf_context/serializer/turtle_serializer.rb

Overview

Abstract serializer

Constant Summary collapse

SUBJECT = 
0
VERB = 
1
OBJECT = 
2

Constants inherited from RecursiveSerializer

RecursiveSerializer::INDENT_STRING, RecursiveSerializer::MAX_DEPTH

Instance Attribute Summary

Attributes inherited from AbstractSerializer

#base, #graph

Instance Method Summary collapse

Methods inherited from RecursiveSerializer

#add_namespace, #indent, #initialize, #is_done?, #order_subjects, #predicate_order, #preprocess, #ref_count, #sort_properties, #subject_done, #top_classes, #uri_binding, #write

Methods inherited from AbstractSerializer

#initialize, #relativize

Constructor Details

This class inherits a constructor from RdfContext::RecursiveSerializer

Instance Method Details

#do_list(l) ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 100

def do_list(l)
  puts "do_list: #{l.inspect}" if ::RdfContext::debug?
  position = SUBJECT
  while l do
    p = @graph.properties(l)
    item = p.fetch(RDF_NS.first.to_s, []).first
    if item
      path(item, position)
      subject_done(l)
      position = OBJECT
    end
    l = p.fetch(RDF_NS.rest.to_s, []).first
  end
end

#end_document ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 80

def end_document; end

#get_qname(uri) ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 42

def get_qname(uri)
  if uri.is_a?(URIRef)
    md = relativize(uri)
    return "<#{md}>" unless md == uri.to_s
    
    super(uri)
  end
end

#is_valid_list(l) ⇒ Object (protected)

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



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 83

def is_valid_list(l)
  props = @graph.properties(l)
  #puts "is_valid_list: #{props.inspect}" if ::RdfContext::debug?
  return false unless props.has_key?(RDF_NS.first.to_s) || l == RDF_NS.nil
  while l && l != RDF_NS.nil do
    #puts "is_valid_list(length): #{props.length}" if ::RdfContext::debug?
    return false unless props.has_key?(RDF_NS.first.to_s) && props.has_key?(RDF_NS.rest.to_s)
    n = props[RDF_NS.rest.to_s]
    #puts "is_valid_list(n): #{n.inspect}" if ::RdfContext::debug?
    return false unless n.is_a?(Array) && n.length == 1
    l = n.first
    props = @graph.properties(l)
  end
  #puts "is_valid_list: valid" if ::RdfContext::debug?
  true
end

#label(node) ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 62

def label(node)
  get_qname(node) || node.to_n3
end

#object_list(objects) ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 166

def object_list(objects)
  puts "object_list: #{objects.inspect}" if ::RdfContext::debug?
  return if objects.empty?

  objects.each_with_index do |obj, i|
    write(",\n#{indent(4)}") if i > 0
    path(obj, OBJECT)
  end
end

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



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 146

def p_default(node, position)
  #puts "p_default: #{node.inspect}, #{position}" if ::RdfContext::debug?
  l = (position == SUBJECT ? "" : " ") + label(node)
  write(l)
end

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



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 115

def p_list(node, position)
  return false if !is_valid_list(node)
  #puts "p_list: #{node.inspect}, #{position}" if ::RdfContext::debug?

  write(position == SUBJECT ? "(" : " (")
  @depth += 2
  do_list(node)
  @depth -= 2
  write(')')
end

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



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 132

def p_squared(node, position)
  return false unless p_squared?(node, position)

  #puts "p_squared: #{node.inspect}, #{position}" if ::RdfContext::debug?
  subject_done(node)
  write(position == SUBJECT ? '[' : ' [')
  @depth += 2
  predicate_list(node)
  @depth -= 2
  write(']')
  
  true
end

#p_squared?(node, position) ⇒ Boolean (protected)

Returns:

  • (Boolean) 


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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 126

def p_squared?(node, position)
  node.is_a?(BNode) &&
    !@serialized.has_key?(node) &&
    ref_count(node) <= 1
end

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

Raises:



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 152

def path(node, position)
  puts "path: #{node.inspect}, pos: #{position}, []: #{is_valid_list(node)}, p2?: #{p_squared?(node, position)}, rc: #{ref_count(node)}" if ::RdfContext::debug?
  raise RdfException, "Cannot serialize node '#{node}'" unless p_list(node, position) || p_squared(node, position) || p_default(node, position)
end

#predicate_list(subject) ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 176

def predicate_list(subject)
  properties = @graph.properties(subject)
  prop_list = sort_properties(properties) - [RDF_NS.first.to_s, RDF_NS.rest.to_s]
  puts "predicate_list: #{prop_list.inspect}" if ::RdfContext::debug?
  return if prop_list.empty?

  prop_list.each_with_index do |prop, i|
    write(";\n#{indent(2)}") if i > 0
    verb(URIRef.new(prop))
    object_list(properties[prop])
  end
end

#preprocess_triple(triple) ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 51

def preprocess_triple(triple)
  super
  
  # Pre-fetch qnames, to fill namespaces
  get_qname(triple.subject)
  get_qname(triple.predicate)
  get_qname(triple.object)

  @references[triple.predicate] = ref_count(triple.predicate) + 1
end

#reset ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 36

def reset
  super
  @shortNames = {}
  @started = false
end

#s_default(subject) ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 204

def s_default(subject)
  write("\n#{indent}")
  path(subject, SUBJECT)
  predicate_list(subject)
  write(" .")
  true
end

#s_squared(subject) ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 193

def s_squared(subject)
  return false unless s_squared?(subject)
  
  write("\n#{indent} [")
  @depth += 1
  predicate_list(subject)
  @depth -= 1
  write("] .")
  true
end

#s_squared?(subject) ⇒ Boolean (protected)

Returns:

  • (Boolean) 


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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 189

def s_squared?(subject)
  ref_count(subject) == 0 && subject.is_a?(BNode) && !is_valid_list(subject)
end

#serialize(stream, options = {})

This method returns an undefined value.

Serialize the graph

Parameters:

  • stream (IO, StreamIO) —

    Stream in which to place serialized graph

  • options (Hash) (defaults to: {}) —

    a customizable set of options

Options Hash (options):

  • :base (URIRef, String) — default: nil —

    Base URI of graph, used to shorting URI references



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 13

def serialize(stream, options = {})
  puts "\nserialize: #{@graph.inspect}" if ::RdfContext::debug?
  reset
  @stream = stream
  @base = options[:base]
  
  @graph.bind(RDF_NS)
  @graph.bind(RDFS_NS)
  
  preprocess
  start_document

  order_subjects.each do |subject|
    #puts "subj: #{subject.inspect}"
    unless is_done?(subject)
      statement(subject)
    end
  end
  
  end_document
end

#start_document ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 66

def start_document
  @started = true
  
  write("#{indent}@base <#{@base}> .\n") if @base
  
  ns_list = @namespaces.values.sort_by {|ns| ns.prefix}
  unless ns_list.empty?
    ns_str = ns_list.map do |ns|
      "#{indent}@prefix #{ns.prefix}: <#{ns.uri}> ."
    end.join("\n") + "\n"
    write(ns_str)
  end
end

#statement(subject) ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 212

def statement(subject)
  puts "statement: #{subject.inspect}, s2?: #{s_squared(subject)}" if ::RdfContext::debug?
  subject_done(subject)
  s_squared(subject) || s_default(subject)
end

#verb(node) ⇒ Object (protected) 



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# File 'lib/rdf_context/serializer/turtle_serializer.rb', line 157

def verb(node)
  puts "verb: #{node.inspect}" if ::RdfContext::debug?
  if node == RDF_TYPE
    write(" a")
  else
    path(node, VERB)
  end
end