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_array, #as_resource, #blank_node?, #compare_values, #graph?, #has_property, #has_value, #index?, #list?, #node?, #node_or_ref?, #node_reference?, #simple_graph?, #value?

Instance Method Details

#create_node_map(element, graph_map, active_graph: '@default', active_subject: nil, active_property: 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:

  • element (Array, Hash) —

    Expanded JSON-LD input

  • graph_map (Hash) —

    A map of graph name to subjects

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

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

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

    (nil) Node identifier

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

    (nil) Property within current node

  • list (Array) (defaults to: nil) —

    (nil) Used when property value is a list



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# File 'lib/json/ld/flatten.rb', line 21

def create_node_map(element, graph_map,
                    active_graph: '@default',
                    active_subject: nil,
                    active_property: nil,
                    list: nil)
  if element.is_a?(Array)
    # If element is an array, process each entry in element recursively by passing item for element, node map, active graph, active subject, active property, and list.
    element.map do |o|
      create_node_map(o, graph_map,
                      active_graph: active_graph,
                      active_subject: active_subject,
                      active_property: active_property,
                      list: list)
    end
  elsif !element.is_a?(Hash)
    raise "Expected hash or array to create_node_map, got #{element.inspect}"
  else
    graph = (graph_map[active_graph] ||= {})
    subject_node = graph[active_subject]

    # Transform BNode types
    if element.has_key?('@type')
      element['@type'] = Array(element['@type']).map {|t| blank_node?(t) ? namer.get_name(t) : t}
    end

    if value?(element)
      element['@type'] = element['@type'].first if element ['@type']
      if list.nil?
        add_value(subject_node, active_property, element, property_is_array: true, allow_duplicate: false)
      else
        list['@list'] << element
      end
    elsif list?(element)
      result = {'@list' => []}
      create_node_map(element['@list'], graph_map,
                      active_graph: active_graph,
                      active_subject: active_subject,
                      active_property: active_property,
                      list: result)
      if list.nil?
        add_value(subject_node, active_property, result, property_is_array: true)
      else
        list['@list'] << result
      end
    else
      # Element is a node object
      id = element.delete('@id')
      id = namer.get_name(id) if blank_node?(id)

      node = graph[id] ||= {'@id' => id}

      if active_subject.is_a?(Hash)
        # If subject is a hash, then we're processing a reverse-property relationship.
        add_value(node, active_property, active_subject, property_is_array: true, allow_duplicate: false)
      elsif active_property
        reference = {'@id' => id}
        if list.nil?
          add_value(subject_node, active_property, reference, property_is_array: true, allow_duplicate: false)
        else
          list['@list'] << reference
        end
      end

      if element.has_key?('@type')
        add_value(node, '@type', element.delete('@type'), property_is_array: true, allow_duplicate: false)
      end

      if element['@index']
        raise JsonLdError::ConflictingIndexes,
              "Element already has index #{node['@index']} dfferent from #{element['@index']}" if
              node.key?('@index') && node['@index'] != element['@index']
        node['@index'] = element.delete('@index')
      end

      if element['@reverse']
        referenced_node, reverse_map = {'@id' => id}, element.delete('@reverse')
        reverse_map.each do |property, values|
          values.each do |value|
            create_node_map(value, graph_map,
                            active_graph: active_graph,
                            active_subject: referenced_node,
                            active_property: property)
          end
        end
      end

      if element['@graph']
        create_node_map(element.delete('@graph'), graph_map,
                        active_graph: id)
      end

      if element['@included']
        create_node_map(element.delete('@included'), graph_map,
                        active_graph: active_graph)
      end

      element.keys.each do |property|
        value = element[property]

        property = namer.get_name(property) if blank_node?(property)
        node[property] ||= []
        create_node_map(value, graph_map,
                        active_graph: active_graph,
                        active_subject: id,
                        active_property: property)
      end
    end
  end
end