Allow annotation of triples including a triple term, generating a reification.

Author: gkellogg

lib/json/ld/expand.rb

@@ -191,8 +191,8 @@ def expand(input, active_property, context,
             return output_object['@set'] if output_object.key?('@set')
           elsif triple_term?(output_object)
             keys = output_object.keys
-            unless (keys - %w(@triple)).empty?
-              # The result must not contain any keys other than @triple. Otherwise, an invalid triplt term error has been detected and processing is aborted.
+            unless (keys - %w(@triple @annotation)).empty?
+              # The result must not contain any keys other than @triple or @annotation. Otherwise, an invalid triple term error has been detected and processing is aborted.
               raise JsonLdError::InvalidTripleTerm,
                 "triple term has unknown keys: #{output_object.inspect}"
             end
@@ -836,8 +836,8 @@ def expand_object(input, active_property, context, output_object,
           end
         end
 
-        # If result includes @triple, it MUST NOT include any other properties
-        if output_object.key?('@triple') && output_object.keys.length != 1
+        # If result includes @triple, it MUST NOT include any properties other than @annotation
+        if output_object.key?('@triple') && !(output_object.keys - %w(@triple @annotation)).empty?
           raise JsonLdError::InvalidTripleTerm,
             "Triple Term includes extra properties: #{output_object.keys}"
         end

lib/json/ld/flatten.rb

@@ -60,18 +60,12 @@ def create_node_map(element, graph_map,
             # note: active_subject will not be nil.
             if annotation = element.delete('@annotation')
               # rdfstar being true is implicit, as it is checked in expansion
-              as = if node_reference?(active_subject)
-                active_subject['@id']
-              else
-                active_subject
-              end
-
-              reification = {'@id' => as, active_property => [element]}
+              reification = {'@id' => active_subject, active_property => [element]}
 
               # Note that annotation is an array, make the reified subject the id of each member of that array.
               annotation.each do |a|
-                # XXX may be zero or more reifiers; use bnode for now.
-                reifier = namer.get_name
+                # Use an provided reifier before allocating a fresh blank node
+                reifier = a.fetch('@id', namer.get_name)
                 a = a.merge('@id' => reifier, '@reifies' => reification)
 
                 # Invoke recursively using annotation.
@@ -97,13 +91,28 @@ def create_node_map(element, graph_map,
               list['@list'] << result
             end
           elsif triple_term?(element)
-            # Add just the @triple member from element as the value of the property in the subject node.
-            # FIXME: if a triple term can have other properties, the triple term would need to be its own entry in the node mode.
-            add_value(subject_node, active_property, element.dup.delete_if {|k,v| k != '@triple'}, allow_duplicate: false)
-            if element.keys.length != 1
+            unless (element.keys - %w(@triple @annotation)).empty?
               raise "Expected triple term to not have other properties, got #{element.inspect}"
             end
-          else
+
+            if annotation = element.delete('@annotation')
+              # rdfstar being true is implicit, as it is checked in expansion
+              reification = {'@id' => active_subject, active_property => [element]}
+
+              # Note that annotation is an array, make the reified subject the id of each member of that array.
+              annotation.each do |a|
+                # Use an provided reifier before allocating a fresh blank node
+                reifier = a.fetch('@id', namer.get_name)
+                a = a.merge('@id' => reifier, '@reifies' => reification)
+
+                # Invoke recursively using annotation.
+                create_node_map(a, graph_map, active_graph: active_graph, active_subject: reifier)
+              end
+            end
+
+            # Add just the @triple member from element as the value of the property in the subject node.
+            add_value(subject_node, active_property, element.dup.delete_if {|k,v| k != '@triple'}, allow_duplicate: false)
+         else
             # Element is a node object
             id = element.delete('@id')
             id = namer.get_name(id) if blank_node?(id)
@@ -127,7 +136,7 @@ def create_node_map(element, graph_map,
             if annotation = element.delete('@annotation')
               # rdfstar being true is implicit, as it is checked in expansion
               if node_reference?(active_subject)
-                # If this is a node reference, then we're processing a revers relationship
+                # If this is a node reference, then we're processing a reverse relationship
                 as = active_subject['@id']
                 reification = {'@id' => node['@id'], active_property => [{ '@id' => as }]}
               else

spec/expand_spec.rb

@@ -3871,7 +3871,16 @@
               "@annotation": {"ex:certainty": 0.8}
             }
           }),
-          exception: JSON::LD::JsonLdError::InvalidTripleTerm
+          output: %([{
+            "@id": "ex:subj",
+            "ex:value": [{
+              "@triple": {
+                "@id": "ex:rei",
+                "ex:prop": [{"@value": "value"}]
+              },
+              "@annotation": [{"ex:certainty": [{"@value": 0.8}]}]
+            }]
+          }])
         },
         'triple term with reverse relationship': {
           input: %({