From 8898065f7ec31584d0d54953fdac693c547e56d8 Mon Sep 17 00:00:00 2001
From: Gregg Kellogg <gregg@greggkellogg.net>
Date: Sat, 19 Aug 2023 14:25:39 -0700
Subject: [PATCH] Add Enumerable#canonicaliza method, which can be overridden
 by rdf-normalize, which normalizes each statement in an enumerable.

---
 lib/rdf/mixin/enumerable.rb | 22 +++++++++++++++++++++-
 spec/model_value_spec.rb    |  3 ++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/lib/rdf/mixin/enumerable.rb b/lib/rdf/mixin/enumerable.rb
index 708db66b..7400ffea 100644
--- a/lib/rdf/mixin/enumerable.rb
+++ b/lib/rdf/mixin/enumerable.rb
@@ -721,13 +721,33 @@ def enum_graph
     end
     alias_method :enum_graphs, :enum_graph
 
+    ##
+    # Enumerates each statement using its canonical representation.
+    #
+    # @note This is updated by `RDF::Normalize` to also canonicalize blank nodes.
+    #
+    # @return [RDF::Enumerable]
+    def canonicalize
+      this = self
+      Enumerable::Enumerator.new do |yielder|
+        this.send(:each_statement) {|y| yielder << y.canonicalize}
+      end
+    end
+
+    ##
+    # Mutating canonicalization not supported
+    #
+    # @raise NotImplementedError
+    def canonicalize!
+      raise NotImplementedError, "Canonicalizing enumerables not supported"
+    end
+
     ##
     # Returns all RDF statements in `self` as an array.
     #
     # Mixes in `RDF::Enumerable` into the returned object.
     #
     # @return [Array]
-    # @since  0.2.0
     def to_a
       super.extend(RDF::Enumerable)
     end
diff --git a/spec/model_value_spec.rb b/spec/model_value_spec.rb
index af400945..b23775d9 100644
--- a/spec/model_value_spec.rb
+++ b/spec/model_value_spec.rb
@@ -135,9 +135,10 @@
   end
 
   it "#canonicalize!" do
-    [statement, uri, node, literal, graph, statement, variable, list].each do |v|
+    [statement, uri, node, literal, statement, variable, list].each do |v|
       expect(v.canonicalize!).to equal v
     end
+    expect {graph.canonicalize!}.to raise_error(NotImplementedError)
   end
 
   it "#to_rdf" do