Module: JSON::LD::Expand

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

Overview

Expand module, used as part of API

Constant Summary collapse

CONTAINER_INDEX_ID_TYPE =

The following constant is used to reduce object allocations

Set['@index', '@id', '@type'].freeze
KEY_ID = 
%w[@id].freeze
KEYS_VALUE_LANGUAGE_TYPE_INDEX_DIRECTION = 
%w[@value @language @type @index @direction @annotation].freeze
KEYS_SET_LIST_INDEX = 
%w[@set @list @index].freeze
KEYS_INCLUDED_TYPE_REVERSE = 
%w[@included @type @reverse].freeze

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

#expand(input, active_property, context, framing: false, from_map: false, log_depth: nil) ⇒ 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)
  • framing (Boolean) (defaults to: false) —

    (false) Special rules for expanding a frame

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

    Expanding from a map, which could be an ‘@type` map, so don’t clear out context term definitions

Returns:

  • (Array<Hash{String => Object}>) 


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# File 'lib/json/ld/expand.rb', line 31

def expand(input, active_property, context,
           framing: false, from_map: false, log_depth: nil)
  # log_debug("expand", depth: log_depth.to_i) {"input: #{input.inspect}, active_property: #{active_property.inspect}, context: #{context.inspect}"}
  framing = false if active_property == '@default'
  if active_property
    expanded_active_property = context.expand_iri(active_property, vocab: true, as_string: true,
      base: @options[:base])
  end

  # Use a term-specific context, if defined, based on the non-type-scoped context.
  if active_property && context.term_definitions[active_property]
    property_scoped_context = context.term_definitions[active_property].context
  end
  # log_debug("expand", depth: log_depth.to_i) {"property_scoped_context: #{property_scoped_context.inspect}"} unless property_scoped_context.nil?

  case input
  when Array
    # If element is an array,
    is_list = context.container(active_property).include?('@list')
    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,
        framing: framing,
        from_map: from_map,
        log_depth: log_depth.to_i + 1)

      # 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
      if is_list && v.is_a?(Array)
        # Make sure that no member of v contains an annotation object
        if v.any? { |n| n.is_a?(Hash) && n.key?('@annotation') }
          raise JsonLdError::InvalidAnnotation,
            "A list element must not contain @annotation."
        end
        v = { "@list" => v }
      end

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

  when Hash
    if context.previous_context
      expanded_key_map = input.keys.inject({}) do |memo, key|
        memo.merge(key => context.expand_iri(key, vocab: true, as_string: true, base: @options[:base]))
      end
      # Revert any previously type-scoped term definitions, unless this is from a map, a value object or a subject reference
      revert_context = !from_map &&
                       !expanded_key_map.value?('@value') &&
                       expanded_key_map.values != ['@id']

      # If there's a previous context, the context was type-scoped
      # log_debug("expand", depth: log_depth.to_i) {"previous_context: #{context.previous_context.inspect}"} if revert_context
      context = context.previous_context if revert_context
    end

    # Apply property-scoped context after reverting term-scoped context
    unless property_scoped_context.nil?
      context = context.parse(property_scoped_context, base: @options[:base], override_protected: true)
    end
    # log_debug("expand", depth: log_depth.to_i) {"after property_scoped_context: #{context.inspect}"} unless property_scoped_context.nil?

    # 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.key?('@context')
      context = context.parse(input['@context'], base: @options[:base])
      # log_debug("expand", depth: log_depth.to_i) {"context: #{context.inspect}"}
    end

    # Set the type-scoped context to the context on input, for use later
    type_scoped_context = context

    output_object = {}

    # See if keys mapping to @type have terms with a local context
    type_key = nil
    (input.keys - %w[@context]).sort
      .select { |k| context.expand_iri(k, vocab: true, base: @options[:base]) == '@type' }
      .each do |tk|
      type_key ||= tk # Side effect saves the first found key mapping to @type
      Array(input[tk]).sort.each do |term|
        if type_scoped_context.term_definitions[term]
          term_context = type_scoped_context.term_definitions[term].context
        end
        unless term_context.nil?
          # log_debug("expand", depth: log_depth.to_i) {"term_context[#{term}]: #{term_context.inspect}"}
          context = context.parse(term_context, base: @options[:base], propagate: false)
        end
      end
    end

    # Process each key and value in element. Ignores @nesting content
    expand_object(input, active_property, context, output_object,
      expanded_active_property: expanded_active_property,
      framing: framing,
      type_key: type_key,
      type_scoped_context: type_scoped_context,
      log_depth: log_depth.to_i + 1)

    # log_debug("output object", depth: log_depth.to_i) {output_object.inspect}

    # If result contains the key @value:
    if value?(output_object)
      keys = output_object.keys
      unless (keys - KEYS_VALUE_LANGUAGE_TYPE_INDEX_DIRECTION).empty?
        # The result must not contain any keys other than @direction, @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

      if keys.include?('@type') && !(keys & %w[@language @direction]).empty?
        # @type is inconsistent with either @language or @direction
        raise JsonLdError::InvalidValueObject,
          "value object must not include @type with either @language or @direction: #{output_object.inspect}"
      end

      if output_object.key?('@language') && Array(output_object['@language']).empty?
        output_object.delete('@language')
      end
      type_is_json = output_object['@type'] == '@json'
      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 and @type is not @json.
      ary = Array(output_object['@value'])
      return nil if ary.empty? && !type_is_json

      if output_object['@type'] == '@json' && context.processingMode('json-ld-1.1')
        # Any value of @value is okay if @type: @json
      elsif !ary.all? { |v| v.is_a?(String) || (v.is_a?(Hash) && v.empty?) } && output_object.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 output_object['@type'] &&
            (!Array(output_object['@type']).all? do |t|
               (t.is_a?(String) && RDF::URI(t).valid? && !t.start_with?('_:')) ||
               (t.is_a?(Hash) && t.empty?)
             end ||
             (!framing && !output_object['@type'].is_a?(String)))
        # 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 or '@json': #{output_object.inspect}"
      elsif !framing && !output_object.fetch('@type', '').is_a?(String) &&
            RDF::URI(t).valid? && !t.start_with?('_:')
        # 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 or '@json': #{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.
      unless (output_object.keys - KEYS_SET_LIST_INDEX).empty?
        raise JsonLdError::InvalidSetOrListObject,
          "@set or @list may only contain @index: #{output_object.keys.inspect}"
      end

      # If result contains the key @set, then set result to the key's associated value.
      return output_object['@set'] if output_object.key?('@set')
    elsif output_object['@annotation']
      # Otherwise, if result contains the key @annotation,
      # the array value must all be node objects without an @id property, otherwise, an invalid annotation error has been detected and processing is aborted.
      unless output_object['@annotation'].all? { |o| node?(o) && !o.key?('@id') }
        raise JsonLdError::InvalidAnnotation,
          "@annotation must reference node objects without @id."
      end

      # Additionally, the property must not be used if there is no active property, or the expanded active property is @graph.
      if %w[@graph @included].include?(expanded_active_property || '@graph')
        raise JsonLdError::InvalidAnnotation,
          "@annotation must not be used on a top-level object."
      end

    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 (expanded_active_property || '@graph') == '@graph' &&
       (output_object.key?('@value') || output_object.key?('@list') ||
       ((output_object.keys - KEY_ID).empty? && !framing))
      # log_debug(" =>", depth: log_depth.to_i) { "empty top-level: " + output_object.inspect}
      return nil
    end

    # Re-order result keys if ordering
    if @options[: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? || expanded_active_property == '@graph'

    # Apply property-scoped context
    unless property_scoped_context.nil?
      context = context.parse(property_scoped_context,
        base: @options[:base],
        override_protected: true)
    end
    # log_debug("expand", depth: log_depth.to_i) {"property_scoped_context: #{context.inspect}"} unless property_scoped_context.nil?

    context.expand_value(active_property, input, base: @options[:base])
  end

  # log_debug(depth: log_depth.to_i) {" => #{result.inspect}"}
end