Module: JSON::LD::Flatten

Includes:
Utils
Included in:
API
Defined in:
lib/json/ld/flatten.rb

Instance Method Summary collapse

Methods included from Utils

#add_value, #as_resource, #blank_node?, #compare_values, #has_property, #has_value, #index?, #list?, #node?, #node_reference?, #value?

Instance Method Details

#create_node_map(input, graphs, graph = '@default', name = nil, list = nil) ⇒ Object

This algorithm creates a JSON object node map holding an indexed representation of the graphs and nodes represented in the passed expanded document. All nodes that are not uniquely identified by an IRI get assigned a (new) blank node identifier. The resulting node map will have a member for every graph in the document whose value is another object with a member for every node represented in the document. The default graph is stored under the @default member, all other graphs are stored under their graph name.

Parameters:

  • input (Array, Hash) —

    Expanded JSON-LD input

  • graphs (Hash) —

    A map of graph name to subjects

  • graph (String) (defaults to: '@default') —

    The name of the currently active graph that the processor should use when processing.

  • name (String) (defaults to: nil) —

    The name assigned to the current input if it is a bnode

  • list (Array) (defaults to: nil) —

    List to append to, nil for none



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# File 'lib/json/ld/flatten.rb', line 17

def create_node_map(input,
                    graphs,
                    graph = '@default',
                    name  = nil,
                    list  = nil)
  depth do
    debug("node_map") {"graph: #{graph}, input: #{input.inspect}, name: #{name}"}
    case input
    when Array
      # If input is an array, process each entry in input recursively by passing item for input, node map, active graph, active subject, active property, and list.
      input.map {|o| create_node_map(o, graphs, graph, nil, list)}
    when Hash
      type = input['@type']
      if value?(input)
        # Rename blanknode @type
        input['@type'] = namer.get_name(type) if type && blank_node?(type)
        list << input if list
      else
        # Input is a node definition

        # spec requires @type to be named first, so assign names early
        Array(type).each {|t| namer.get_name(t) if blank_node?(t)}

        # get name for subject
        if name.nil?
          name ||= input['@id']
          name = namer.get_name(name) if blank_node?(name)
        end

        # add subject reference to list
        list << {'@id' => name} if list

        # create new subject or merge into existing one
        subject = (graphs[graph] ||= {})[name] ||= {'@id' => name}

        input.keys.kw_sort.each do |property|
          objects = input[property]
          case property
          when '@id'
            # Skip
          when '@reverse'
            # handle reverse properties
            referenced_node, reverse_map = {'@id' => name}, objects
            reverse_map.each do |reverse_property, items|
              items.each do |item|
                item_name = item['@id']
                item_name = namer.get_name(item_name) if blank_node?(item_name)
                create_node_map(item, graphs, graph, item_name)
                add_value(graphs[graph][item_name],
                          reverse_property,
                          referenced_node,
                          property_is_array: true,
                          allow_duplicate: false)
              end
            end
          when '@graph'
            graphs[name] ||= {}
            g = graph == '@merged' ? graph : name
            create_node_map(objects, graphs, g)
          when /^@(?!type)/
            # copy non-@type keywords
            if property == '@index' && subject['@index']
              raise JsonLdError::ConflictingIndexes,
                    "Element already has index #{subject['@index']} dfferent from #{input['@index']}" if
                    subject['@index'] != input['@index']
              subject['@index'] = input.delete('@index')
            end
            subject[property] = objects
          else
            # if property is a bnode, assign it a new id
            property = namer.get_name(property) if blank_node?(property)

            add_value(subject, property, [], property_is_array: true) if objects.empty?

            objects.each do |o|
              o = namer.get_name(o) if property == '@type' && blank_node?(o)

              case
              when node?(o) || node_reference?(o)
                id = o['@id']
                id = namer.get_name(id) if blank_node?(id)

                # add reference and recurse
                add_value(subject, property, {'@id' => id}, property_is_array: true, allow_duplicate: false)
                create_node_map(o, graphs, graph, id)
              when list?(o)
                olist = []
                create_node_map(o['@list'], graphs, graph, name, olist)
                o = {'@list' => olist}
                add_value(subject, property, o, property_is_array: true, allow_duplicate: true)
              else
                # handle @value
                create_node_map(o, graphs, graph, name)
                add_value(subject, property, o, property_is_array: true, allow_duplicate: false)
              end
            end
          end
        end
      end
    else
      # add non-object to list
      list << input if list
    end
  end
end