# -*- encoding: utf-8 -*-
# frozen_string_literal: true
require 'rdf/nquads'
module JSON::LD
module FromRDF
include Utils
##
# Generate a JSON-LD array representation from an array of `RDF::Statement`.
# Representation is in expanded form
#
# @param [Array<RDF::Statement>, RDF::Enumerable] dataset
# @param [Boolean] useRdfType (false)
# If set to `true`, the JSON-LD processor will treat `rdf:type` like a normal property instead of using `@type`.
# @param [Boolean] useNativeTypes (false) use native representations
# @param extendedRepresentation (false)
# Use the extended internal representation for native types.
#
# @return [Array<Hash>] the JSON-LD document in normalized form
def from_statements(dataset, useRdfType: false, useNativeTypes: false, extendedRepresentation: false)
default_graph = {}
graph_map = {'@default' => default_graph}
referenced_once = {}
value = nil
# Create an entry for compound-literal node detection
compound_literal_subjects = {}
# Create a map for node to object representation
# For each statement in dataset
dataset.each do |statement|
# log_debug("statement") { statement.to_nquads.chomp}
name = statement.graph_name ? @context.expand_iri(statement.graph_name, base: @options[:base]).to_s : '@default'
# Create a graph entry as needed
node_map = graph_map[name] ||= {}
compound_literal_subjects[name] ||= {}
default_graph[name] ||= {'@id' => name} unless name == '@default'
subject = statement.subject.statement? ?
resource_representation(statement.subject, useNativeTypes, extendedRepresentation)['@id'].to_json_c14n :
statement.subject.to_s
node = node_map[subject] ||= resource_representation(statement.subject, useNativeTypes, extendedRepresentation)
# If predicate is rdf:datatype, note subject in compound literal subjects map
if @options[:rdfDirection] == 'compound-literal' && statement.predicate == RDF.to_uri + 'direction'
compound_literal_subjects[name][subject] ||= true
end
# If object is an IRI, blank node identifier, or statement, and node map does not have an object member, create one and initialize its value to a new JSON object consisting of a single member @id whose value is set to object.
unless statement.object.literal?
object = statement.object.statement? ?
resource_representation(statement.object, useNativeTypes, extendedRepresentation)['@id'].to_json_c14n :
statement.object.to_s
node_map[object] ||=
resource_representation(statement.object, useNativeTypes, extendedRepresentation)
end
# If predicate equals rdf:type, and object is an IRI or blank node identifier, append object to the value of the @type member of node. If no such member exists, create one and initialize it to an array whose only item is object. Finally, continue to the next RDF triple.
if statement.predicate == RDF.type && statement.object.resource? && !useRdfType
merge_value(node, '@type', statement.object.to_s)
next
end
# Set value to the result of using the RDF to Object Conversion algorithm, passing object, rdfDirection, and use native types.
value = resource_representation(statement.object, useNativeTypes, extendedRepresentation)
merge_value(node, statement.predicate.to_s, value)
# If object is a blank node identifier or rdf:nil, it might represent the a list node:
if statement.object == RDF.nil
# Append a new JSON object consisting of three members, node, property, and value to the usages array. The node member is set to a reference to node, property to predicate, and value to a reference to value.
object = node_map[statement.object.to_s]
merge_value(object, :usages, {
node: node,
property: statement.predicate.to_s,
value: value
})
elsif referenced_once.key?(statement.object.to_s)
referenced_once[statement.object.to_s] = false
elsif statement.object.node?
referenced_once[statement.object.to_s] = {
node: node,
property: statement.predicate.to_s,
value: value
}
end
end
# For each name and graph object in graph map:
graph_map.each do |name, graph_object|
# If rdfDirection is compound-literal, check referenced_once for entries from compound_literal_subjects
compound_literal_subjects.fetch(name, {}).keys.each do |cl|
node = referenced_once[cl][:node]
next unless node.is_a?(Hash)
property = referenced_once[cl][:property]
value = referenced_once[cl][:value]
cl_node = graph_map[name].delete(cl)
next unless cl_node.is_a?(Hash)
node[property].select do |v|
next unless v['@id'] == cl
v.delete('@id')
v['@value'] = cl_node[RDF.value.to_s].first['@value']
if cl_node[RDF.to_uri.to_s + 'language']
lang = cl_node[RDF.to_uri.to_s + 'language'].first['@value']
if lang !~ /^[a-zA-Z]{1,8}(-[a-zA-Z0-9]{1,8})*$/
warn "i18n datatype language must be valid BCP47: #{lang.inspect}"
end
v['@language'] = lang
end
v['@direction'] = cl_node[RDF.to_uri.to_s + 'direction'].first['@value']
end
end
nil_var = graph_object.fetch(RDF.nil.to_s, {})
# For each item usage in the usages member of nil, perform the following steps:
nil_var.fetch(:usages, []).each do |usage|
node, property, head = usage[:node], usage[:property], usage[:value]
list, list_nodes = [], []
# If property equals rdf:rest, the value associated to the usages member of node has exactly 1 entry, node has a rdf:first and rdf:rest property, both of which have as value an array consisting of a single element, and node has no other members apart from an optional @type member whose value is an array with a single item equal to rdf:List, node represents a well-formed list node. Continue with the following steps:
# log_debug("list element?") {node.to_json(JSON_STATE) rescue 'malformed json'}
while property == RDF.rest.to_s &&
blank_node?(node) &&
referenced_once[node['@id']] &&
node.keys.none? {|k| !["@id", '@type', :usages, RDF.first.to_s, RDF.rest.to_s].include?(k)} &&
(f = node[RDF.first.to_s]).is_a?(Array) && f.length == 1 &&
(r = node[RDF.rest.to_s]).is_a?(Array) && r.length == 1 &&
((t = node['@type']).nil? || t == [RDF.List.to_s])
list << Array(node[RDF.first.to_s]).first
list_nodes << node['@id']
# get next node, moving backwards through list
node_usage = referenced_once[node['@id']]
node, property, head = node_usage[:node], node_usage[:property], node_usage[:value]
end
head.delete('@id')
head['@list'] = list.reverse
list_nodes.each {|node_id| graph_object.delete(node_id)}
end
# Create annotations on graph object
create_annotations(graph_object)
end
result = []
default_graph.keys.opt_sort(ordered: @options[:ordered]).each do |subject|
node = default_graph[subject]
if graph_map.key?(subject)
node['@graph'] = []
graph_map[subject].keys.opt_sort(ordered: @options[:ordered]).each do |s|
n = graph_map[subject][s]
n.delete(:usages)
node['@graph'] << n unless node_reference?(n)
end
end
node.delete(:usages)
result << node unless node_reference?(node)
end
# log_debug("fromRdf") {result.to_json(JSON_STATE) rescue 'malformed json'}
result
end
private
RDF_LITERAL_NATIVE_TYPES = Set.new([RDF::XSD.boolean, RDF::XSD.integer, RDF::XSD.double]).freeze
def resource_representation(resource, useNativeTypes, extendedRepresentation)
case resource
when RDF::Statement
# Note, if either subject or object are a BNode which is used elsewhere,
# this might not work will with the BNode accounting from above.
rep = {'@id' => resource_representation(resource.subject, false, extendedRepresentation)}
if resource.predicate == RDF.type
rep['@id'].merge!('@type' => resource.object.to_s)
else
rep['@id'].merge!(
resource.predicate.to_s =>
as_array(resource_representation(resource.object, useNativeTypes, extendedRepresentation)))
end
rep
when RDF::Literal
base = @options[:base]
rdfDirection = @options[:rdfDirection]
res = {}
if resource.datatype == RDF::URI(RDF.to_uri + "JSON") && @context.processingMode('json-ld-1.1')
res['@type'] = '@json'
res['@value'] = begin
::JSON.parse(resource.object)
rescue ::JSON::ParserError => e
raise JSON::LD::JsonLdError::InvalidJsonLiteral, e.message
end
elsif useNativeTypes && extendedRepresentation
res['@value'] = resource # Raw literal
elsif resource.datatype.start_with?("https://www.w3.org/ns/i18n#") && rdfDirection == 'i18n-datatype' && @context.processingMode('json-ld-1.1')
lang, dir = resource.datatype.fragment.split('_')
res['@value'] = resource.to_s
unless lang.empty?
if lang !~ /^[a-zA-Z]{1,8}(-[a-zA-Z0-9]{1,8})*$/
if options[:validate]
raise JsonLdError::InvalidLanguageMapping, "rdf:language must be valid BCP47: #{lang.inspect}"
else
warn "rdf:language must be valid BCP47: #{lang.inspect}"
end
end
res['@language'] = lang
end
res['@direction'] = dir
elsif useNativeTypes && RDF_LITERAL_NATIVE_TYPES.include?(resource.datatype) && resource.valid?
res['@value'] = resource.object
else
resource.canonicalize! if resource.valid? && resource.datatype == RDF::XSD.double
if resource.datatype?
res['@type'] = resource.datatype.to_s
elsif resource.language?
res['@language'] = resource.language.to_s
end
res['@value'] = resource.to_s
end
res
else
{'@id' => resource.to_s}
end
end
end
end