Module: JSON::LD::ToRDF

Includes:
Utils
Included in:
API, StreamingReader
Defined in:
vendor/bundler/ruby/3.3.0/bundler/gems/json-ld-f1de87658826/lib/json/ld/to_rdf.rb

Instance Method Summary collapse

Methods included from Utils

#add_value, #as_array, #as_resource, #blank_node?, #compare_values, #graph?, #has_value?, #index?, #list?, #node?, #node_or_ref?, #node_reference?, #property?, #simple_graph?, #value?

Instance Method Details

#item_to_rdf(item, graph_name: nil, quoted: false) {|statement| ... } ⇒ Object

Returns RDF::Resource the subject of this item.

Parameters:

  • item (Hash{String => Object})
  • graph_name (RDF::Resource) (defaults to: nil)
  • quoted (Boolean) (defaults to: false) —

    emitted triples are quoted triples.

Yields:

  • statement

Yield Parameters:

Returns:

  • RDF::Resource the subject of this item



19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
 
# File 'vendor/bundler/ruby/3.3.0/bundler/gems/json-ld-f1de87658826/lib/json/ld/to_rdf.rb', line 19

def item_to_rdf(item, graph_name: nil, quoted: false, &block)
  # Just return value object as Term
  return unless item

  if value?(item)
    value = item.fetch('@value')
    datatype = item.fetch('@type', nil)

    datatype = RDF_JSON if datatype == '@json'

    case value
    when RDF::Value
      return value
    when TrueClass, FalseClass
      # If value is true or false, then set value its canonical lexical form as defined in the section Data Round Tripping. If datatype is null, set it to xsd:boolean.
      value = value.to_s
      datatype ||= RDF::XSD.boolean.to_s
    when Numeric
      # Otherwise, if value is a number, then set value to its canonical lexical form as defined in the section Data Round Tripping. If datatype is null, set it to either xsd:integer or xsd:double, depending on if the value contains a fractional and/or an exponential component.
      value = if datatype == RDF_JSON
        value.to_json_c14n
      else
        # Don't serialize as double if there are no fractional bits
        as_double = value.ceil != value || value >= 1e21 || datatype == RDF::XSD.double
        lit = if as_double
          RDF::Literal::Double.new(value, canonicalize: true)
        else
          RDF::Literal.new(value.numerator, canonicalize: true)
        end

        datatype ||= lit.datatype
        lit.to_s.sub("E+", "E")
      end
    when Array, Hash
      # Only valid for rdf:JSON
      value = value.to_json_c14n
    else
      if item.key?('@direction') && @options[:rdfDirection]
        # Either serialize using a datatype, or a compound-literal
        case @options[:rdfDirection]
        when 'i18n-datatype'
          datatype = RDF::URI("https://www.w3.org/ns/i18n##{item.fetch('@language',
            '').downcase}_#{item['@direction']}")
        when 'compound-literal'
          cl = RDF::Node.new
          yield RDF::Statement(cl, RDF.value, item['@value'].to_s)
          yield RDF::Statement(cl, RDF_LANGUAGE, item['@language'].downcase) if item['@language']
          yield RDF::Statement(cl, RDF_DIRECTION, item['@direction'])
          return cl
        end
      end

      # Otherwise, if datatype is null, set it to xsd:string or xsd:langString, depending on if item has a @language key.
      datatype ||= item.key?('@language') ? RDF.langString : RDF::XSD.string
      value = value.to_json_c14n if datatype == RDF_JSON
    end
    datatype = RDF::URI(datatype) if datatype && !datatype.is_a?(RDF::URI)

    # Initialize literal as an RDF literal using value and datatype. If element has the key @language and datatype is xsd:string, then add the value associated with the @language key as the language of the object.
    language = item.fetch('@language', nil) if datatype == RDF.langString
    return RDF::Literal.new(value, datatype: datatype, language: language)
  elsif list?(item)
    # If item is a list object, initialize list_results as an empty array, and object to the result of the List Conversion algorithm, passing the value associated with the @list key from item and list_results.
    return parse_list(item['@list'], graph_name: graph_name, &block)
  end

  subject = case item['@id']
  when nil then node
  when String then as_resource(item['@id'])
  when Object
    # Embedded/quoted statement
    # (No error checking, as this is done in expansion)
    to_enum(:item_to_rdf, item['@id'], quoted: true).to_a.first
  end

  # log_debug("item_to_rdf")  {"subject: #{subject.to_ntriples rescue 'malformed rdf'}"}
  item.each do |property, values|
    case property
    when '@type'
      # If property is @type, construct triple as an RDF Triple composed of id, rdf:type, and object from values where id and object are represented either as IRIs or Blank Nodes
      values.each do |v|
        object = as_resource(v)
        # log_debug("item_to_rdf")  {"type: #{object.to_ntriples rescue 'malformed rdf'}"}
        yield RDF::Statement(subject, RDF.type, object, graph_name: graph_name, quoted: quoted)
      end
    when '@graph'
      values = [values].compact unless values.is_a?(Array)
      values.each do |nd|
        item_to_rdf(nd, graph_name: subject, quoted: quoted, &block)
      end
    when '@reverse'
      raise "Huh?" unless values.is_a?(Hash)

      values.each do |prop, vv|
        predicate = as_resource(prop)
        # log_debug("item_to_rdf")  {"@reverse predicate: #{predicate.to_ntriples rescue 'malformed rdf'}"}
        # For each item in values
        vv.each do |v|
          # Item is a node definition. Generate object as the result of the Object Converstion algorithm passing item.
          object = item_to_rdf(v, graph_name: graph_name, &block)
          # log_debug("item_to_rdf")  {"subject: #{object.to_ntriples rescue 'malformed rdf'}"}
          # yield subject, prediate, and literal to results.
          yield RDF::Statement(object, predicate, subject, graph_name: graph_name, quoted: quoted)
        end
      end
    when '@included'
      values.each do |v|
        item_to_rdf(v, graph_name: graph_name, &block)
      end
    when /^@/
      # Otherwise, if @type is any other keyword, skip to the next property-values pair
    else
      # Otherwise, property is an IRI or Blank Node identifier
      # Initialize predicate from  property as an IRI or Blank node
      predicate = as_resource(property)
      # log_debug("item_to_rdf")  {"predicate: #{predicate.to_ntriples rescue 'malformed rdf'}"}

      # For each item in values
      values.each do |v|
        if list?(v)
          # log_debug("item_to_rdf")  {"list: #{v.inspect}"}
          # If item is a list object, initialize list_results as an empty array, and object to the result of the List Conversion algorithm, passing the value associated with the @list key from item and list_results.
          object = parse_list(v['@list'], graph_name: graph_name, &block)

          # Append a triple composed of subject, prediate, and object to results and add all triples from list_results to results.
        else
          # Otherwise, item is a value object or a node definition. Generate object as the result of the Object Converstion algorithm passing item.
          object = item_to_rdf(v, graph_name: graph_name, &block)
          # log_debug("item_to_rdf")  {"object: #{object.to_ntriples rescue 'malformed rdf'}"}
          # yield subject, prediate, and literal to results.
        end
        yield RDF::Statement(subject, predicate, object, graph_name: graph_name, quoted: quoted)
      end
    end
  end

  subject
end

#node ⇒ Object

Create a new named node using the sequence



191
192
193
 
# File 'vendor/bundler/ruby/3.3.0/bundler/gems/json-ld-f1de87658826/lib/json/ld/to_rdf.rb', line 191

def node
  RDF::Node.new(namer.get_sym)
end

#parse_list(list, graph_name: nil) {|statement| ... } ⇒ Array<RDF::Statement>

Parse a List

Parameters:

  • list (Array) —

    The Array to serialize as a list

Yields:

  • statement

Yield Parameters:

Returns:



167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
 
# File 'vendor/bundler/ruby/3.3.0/bundler/gems/json-ld-f1de87658826/lib/json/ld/to_rdf.rb', line 167

def parse_list(list, graph_name: nil, &block)
  # log_debug('parse_list') {"list: #{list.inspect}"}

  last = list.pop
  result = first_bnode = last ? node : RDF.nil

  list.each do |list_item|
    # Set first to the result of the Object Converstion algorithm passing item.
    object = item_to_rdf(list_item, graph_name: graph_name, &block)
    yield RDF::Statement(first_bnode, RDF.first, object, graph_name: graph_name)
    rest_bnode = node
    yield RDF::Statement(first_bnode, RDF.rest, rest_bnode, graph_name: graph_name)
    first_bnode = rest_bnode
  end
  if last
    object = item_to_rdf(last, graph_name: graph_name, &block)
    yield RDF::Statement(first_bnode, RDF.first, object, graph_name: graph_name)
    yield RDF::Statement(first_bnode, RDF.rest, RDF.nil, graph_name: graph_name)
  end
  result
end