Add missing Statement#dup. Does not duplicate blank node components.

Author: gkellogg

lib/rdf/model/statement.rb

@@ -437,6 +437,18 @@ def canonicalize
       nil
     end
 
+    # New statement with duplicated components (other than blank nodes)
+    #
+    # @return [RDF::Statement]
+    def dup
+      options = Hash[@options]
+      options[:subject] = subject.is_a?(RDF::Node) ? subject : subject.dup
+      options[:predicate] = predicate.dup
+      options[:object] = object.is_a?(RDF::Node) ? object : object.dup
+      options[:graph_name] = graph_name.is_a?(RDF::Node) ? graph_name : graph_name.dup if graph_name
+      RDF::Statement.new(options)
+    end
+
     ##
     # Returns the terms of this statement as a `Hash`.
     #

spec/model_statement_spec.rb

@@ -79,6 +79,18 @@
     it {is_expected.to be_statement}
     it {is_expected.not_to be_inferred}
     its(:terms) {is_expected.to include(s, p, o)}
+
+    describe "#dup" do
+      its(:dup) {is_expected.to eql(subject)}
+      its(:dup) {is_expected.not_to equal(subject)}
+
+      [:subject, :predicate, :object].each do |c|
+        it "#{c} duplicated as appropriate" do
+          expect(subject.dup.send(c)).to eql(subject.send(c))
+          expect(subject.dup.send(c)).not_to equal(subject.send(c)) unless subject.send(c).is_a?(RDF::Node)
+        end
+      end
+    end
   end
 
   context "when created with a blank node subject" do
@@ -103,6 +115,18 @@
     its(:graph_name) {is_expected.not_to be_nil}
     it {is_expected.to eq stmt}
     it {is_expected.not_to eql stmt}
+
+    describe "#dup" do
+      its(:dup) {is_expected.to eql(subject)}
+      its(:dup) {is_expected.not_to equal(subject)}
+
+      [:subject, :predicate, :object, :graph_name].each do |c|
+        it "#{c} duplicated as appropriate" do
+          expect(subject.dup.send(c)).to eql(subject.send(c))
+          expect(subject.dup.send(c)).not_to equal(subject.send(c)) unless subject.send(c).is_a?(RDF::Node)
+        end
+      end
+    end
   end
 
   context "when created with a default graph" do