Module: JSON::LD::Expand

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

Overview

Expand module, used as part of API

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

#expand(input, active_property, context, ordered: false, framing: false) ⇒ Array<Hash{String => Object}>

Expand an Array or Object given an active context and performing local context expansion.

Parameters:

  • input (Array, Hash)
  • active_property (String)
  • context (Context)
  • ordered (Boolean) (defaults to: false) —

    (true) Ensure output objects have keys ordered properly

  • framing (Boolean) (defaults to: false) —

    (false) Special rules for expanding a frame

Returns:

  • (Array<Hash{String => Object}>) 


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# File 'lib/json/ld/expand.rb', line 22

def expand(input, active_property, context, ordered: false, framing: false)
  #log_debug("expand") {"input: #{input.inspect}, active_property: #{active_property.inspect}, context: #{context.inspect}"}
  framing = false if active_property == '@default'
  result = case input
  when Array
    # If element is an array,
    is_list = context.container(active_property) == %w(@list)
    value = input.each_with_object([]) do |v, memo|
      # Initialize expanded item to the result of using this algorithm recursively, passing active context, active property, and item as element.
      v = expand(v, active_property, context, ordered: ordered, framing: framing)

      # If the active property is @list or its container mapping is set to @list and v is an array, change it to a list object
      v = {"@list" => v} if is_list && v.is_a?(Array)

      case v
      when nil then nil
      when Array then memo.concat(v)
      else            memo << v
      end
    end

    value
  when Hash
    # If element contains the key @context, set active context to the result of the Context Processing algorithm, passing active context and the value of the @context key as local context.
    if input.has_key?('@context')
      context = context.parse(input.delete('@context'))
      #log_debug("expand") {"context: #{context.inspect}"}
    end

    output_object = {}

    # See if keys mapping to @type have terms with a local context
    input.each_pair do |key, val|
      next unless context.expand_iri(key, vocab: true) == '@type'
      Array(val).sort.each do |term|
        term_context = context.term_definitions[term].context if context.term_definitions[term]
        context = term_context ? context.parse(term_context) : context
      end
    end

    # Process each key and value in element. Ignores @nesting content
    expand_object(input, active_property, context, output_object, ordered: ordered, framing: framing)

    #log_debug("output object") {output_object.inspect}

    # If result contains the key @value:
    if value?(output_object)
      unless (output_object.keys - %w(@value @language @type @index)).empty? &&
             !(output_object.key?('@language') && output_object.key?('@type'))
        # The result must not contain any keys other than @value, @language, @type, and @index. It must not contain both the @language key and the @type key. Otherwise, an invalid value object error has been detected and processing is aborted.
        raise JsonLdError::InvalidValueObject,
        "value object has unknown keys: #{output_object.inspect}"
      end

      output_object.delete('@language') if output_object.key?('@language') && Array(output_object['@language']).empty?
      output_object.delete('@type') if output_object.key?('@type') && Array(output_object['@type']).empty?

      # If the value of result's @value key is null, then set result to null.
      ary = Array(output_object['@value'])
      return nil if ary.empty?

      if !ary.all? {|v| v.is_a?(String) || v.is_a?(Hash) && v.empty?} && output_object.has_key?('@language')
        # Otherwise, if the value of result's @value member is not a string and result contains the key @language, an invalid language-tagged value error has been detected (only strings can be language-tagged) and processing is aborted.
        raise JsonLdError::InvalidLanguageTaggedValue,
              "when @language is used, @value must be a string: #{output_object.inspect}"
      elsif !Array(output_object['@type']).all? {|t|
              t.is_a?(String) && RDF::URI(t).absolute? && !t.start_with?('_:') ||
              t.is_a?(Hash) && t.empty?}
        # Otherwise, if the result has a @type member and its value is not an IRI, an invalid typed value error has been detected and processing is aborted.
        raise JsonLdError::InvalidTypedValue,
              "value of @type must be an IRI: #{output_object.inspect}"
      end
    elsif !output_object.fetch('@type', []).is_a?(Array)
      # Otherwise, if result contains the key @type and its associated value is not an array, set it to an array containing only the associated value.
      output_object['@type'] = [output_object['@type']]
    elsif output_object.key?('@set') || output_object.key?('@list')
      # Otherwise, if result contains the key @set or @list:
      # The result must contain at most one other key and that key must be @index. Otherwise, an invalid set or list object error has been detected and processing is aborted.
      raise JsonLdError::InvalidSetOrListObject,
            "@set or @list may only contain @index: #{output_object.keys.inspect}" unless
            (output_object.keys - %w(@set @list @index)).empty?

      # If result contains the key @set, then set result to the key's associated value.
      return output_object['@set'] if output_object.key?('@set')
    end

    # If result contains only the key @language, set result to null.
    return nil if output_object.length == 1 && output_object.key?('@language')

    # If active property is null or @graph, drop free-floating values as follows:
    if (active_property || '@graph') == '@graph' &&
      (output_object.key?('@value') || output_object.key?('@list') ||
       (output_object.keys - %w(@id)).empty? && !framing)
      #log_debug(" =>") { "empty top-level: " + output_object.inspect}
      return nil
    end

    # Re-order result keys if ordering
    if ordered
      output_object.keys.sort.each_with_object({}) {|kk, memo| memo[kk] = output_object[kk]}
    else
      output_object
    end
  else
    # Otherwise, unless the value is a number, expand the value according to the Value Expansion rules, passing active property.
    return nil if input.nil? || active_property.nil? || active_property == '@graph'
    context.expand_value(active_property, input, log_depth: @options[:log_depth])
  end

  #log_debug {" => #{result.inspect}"}
  result
end