get_output_elements (#1154)

* get_get_output_elements

* fix comp error

* address scott's feedback

src/ngraph/node_vector.hpp

@@ -47,6 +47,11 @@ namespace ngraph
         {
         }
 
+        NodeVector(size_t size)
+            : std::vector<std::shared_ptr<Node>>(size)
+        {
+        }
+
         NodeVector& operator=(const NodeVector& other) = default;
 
         NodeVector() {}

src/ngraph/op/batch_norm.cpp

@@ -265,15 +265,9 @@ void ngraph::op::BatchNorm::generate_adjoints(autodiff::Adjoints& adjoints,
     //and get_n() is used to sort the inputs in the same order as Batchnorm's outputs
     //Next, Mean and Variance (`at(1)` and `at(2)`) are extracted
     //Please see `add_output` in `BatchNorm::BatchNorm` for more details
-
-    std::vector<std::shared_ptr<Node>> goes(get_outputs().size());
     if (this->get_training_flag() && get_input_size() == 3)
     {
-        for (auto goe_input : get_output_inputs(0))
-        {
-            auto goe = std::dynamic_pointer_cast<op::GetOutputElement>(goe_input->get_node());
-            goes.at(goe->get_n()) = goe_input->get_node();
-        }
+        auto goes = op::get_output_elements(this->shared_from_this());
         mean = goes.at(1);
         var = goes.at(2);
     }

src/ngraph/op/get_output_element.cpp

@@ -53,3 +53,15 @@ void op::GetOutputElement::generate_adjoints(autodiff::Adjoints& adjoints, const
 
     adjoints.add_delta(get_inputs().at(0).get_output().get_node(), delta, get_n());
 }
+
+NodeVector op::get_output_elements(const std::shared_ptr<Node>& mon)
+{
+    NodeVector goes(mon->get_outputs().size());
+
+    for (auto goe_input : mon->get_output_inputs(0))
+    {
+        auto goe = std::dynamic_pointer_cast<op::GetOutputElement>(goe_input->get_node());
+        goes.at(goe->get_n()) = goe_input->get_node();
+    }
+    return goes;
+}

src/ngraph/op/get_output_element.hpp

@@ -22,6 +22,8 @@ namespace ngraph
 {
     namespace op
     {
+        NodeVector get_output_elements(const std::shared_ptr<Node>& mon);
+
         /// \brief Operation to get an output from a node.
         class GetOutputElement : public Node
         {