1 files changed, 26 insertions, 0 deletions
diff --git a/ruby_2_2/ext/psych/lib/psych/visitors/depth_first.rb b/ruby_2_2/ext/psych/lib/psych/visitors/depth_first.rb
new file mode 100644
index 0000000000..c6eb814ac0
--- /dev/null
+++ b/ruby_2_2/ext/psych/lib/psych/visitors/depth_first.rb
@@ -0,0 +1,26 @@
+module Psych
+  module Visitors
+    class DepthFirst < Psych::Visitors::Visitor
+      def initialize block
+        @block = block
+      end
+
+      private
+
+      def nary o
+        o.children.each { |x| visit x }
+        @block.call o
+      end
+      alias :visit_Psych_Nodes_Stream   :nary
+      alias :visit_Psych_Nodes_Document :nary
+      alias :visit_Psych_Nodes_Sequence :nary
+      alias :visit_Psych_Nodes_Mapping  :nary
+
+      def terminal o
+        @block.call o
+      end
+      alias :visit_Psych_Nodes_Scalar :terminal
+      alias :visit_Psych_Nodes_Alias  :terminal
+    end
+  end
+end