Use weak_ptr for node in inputs/outputs, turn off alignment style.

.clang-format

@@ -6,8 +6,8 @@ Standard: Cpp11
 
 AccessModifierOffset: -4
 
-AlignConsecutiveDeclarations: true
-AlignConsecutiveAssignments: true
+AlignConsecutiveDeclarations: false
+AlignConsecutiveAssignments: false
 AlignTrailingComments: true
 
 AllowShortBlocksOnASingleLine: true

src/ngraph/descriptor/input.cpp

@@ -19,7 +19,7 @@ using namespace ngraph;
 using namespace descriptor;
 
 Input::Input(
-    Node* node, size_t index, size_t argno, size_t arg_index, Output& output)
+    const std::shared_ptr<Node>& node, size_t index, size_t argno, size_t arg_index, Output& output)
     : m_node(node)
     , m_index(index)
     , m_argno(argno)
@@ -31,7 +31,7 @@ Input::Input(
 
 std::shared_ptr<Node> Input::get_node()
 {
-    return m_node->shared_from_this();
+    return m_node.lock();
 }
 
 const Tensor& Input::get_tensor() const

src/ngraph/descriptor/input.hpp

@@ -32,12 +32,12 @@ namespace ngraph
             friend class Node;
 
         public:
-            /// @param node The node that owns this input; not shared to prevent owner loop
+            /// @param node The node that owns this input
             /// @param index The position of this this tensor in all input tensors
             /// @param argno The position of the argument with this tensor
             /// @param arg_index The position of the tensor within the argument's tensors
             /// @param output The output that supplies a value for this input
-            Input(Node*   node,
+            Input(const std::shared_ptr<Node>& node,
                   size_t index,
                   size_t argno,
                   size_t arg_index,
@@ -53,7 +53,7 @@ namespace ngraph
             Tensor& get_tensor();
 
         protected:
-            Node*   m_node;      // The node we are an input for
+            std::weak_ptr<Node> m_node; // The node we are an input for
             size_t m_index;             // Index into all input tensors
             size_t m_argno;             // Arg number for this input
             size_t m_arg_index;         // Index into arg's tensors

src/ngraph/descriptor/output.cpp

@@ -18,7 +18,9 @@ using namespace std;
 using namespace ngraph;
 using namespace descriptor;
 
-Output::Output(Node* node, size_t index, const std::shared_ptr<TensorView>& tensor_view)
+Output::Output(const std::shared_ptr<Node>& node,
+               size_t index,
+               const std::shared_ptr<TensorView>& tensor_view)
     : m_node(node)
     , m_index(index)
     , m_tensor_view(tensor_view)
@@ -33,7 +35,7 @@ void Output::add_input(Input* input)
 
 std::shared_ptr<Node> Output::get_node() const
 {
-    return m_node->shared_from_this();
+    return m_node.lock();
 }
 
 const Tensor& Output::get_tensor() const

src/ngraph/descriptor/output.hpp

@@ -32,10 +32,12 @@ namespace ngraph
             // Output& operator=(const Output&) = delete;
 
         public:
-            /// @param node Node that owns this output. Not shared to prevent owner loop.
+            /// @param node Node that owns this output.
             /// @param index Position of the output tensor in all output tensors
             /// @param tensor_view The view of this tensor; where the value will be written
-            Output(Node* node, size_t index, const std::shared_ptr<TensorView>& tensor_view);
+            Output(const std::shared_ptr<Node>& node,
+                   size_t index,
+                   const std::shared_ptr<TensorView>& tensor_view);
 
             std::shared_ptr<Node> get_node() const;
             size_t get_index() const { return m_index; }
@@ -46,7 +48,7 @@ namespace ngraph
             Tensor& get_tensor();
 
         protected:
-            Node*                       m_node;
+            std::weak_ptr<Node> m_node;
             size_t m_index;
             std::shared_ptr<TensorView> m_tensor_view;
             std::set<Input*> m_inputs;

src/ngraph/node.cpp

@@ -32,9 +32,7 @@ Node::Node(const std::vector<shared_ptr<Node>>& arguments, shared_ptr<ValueType>
     }
 }
 
-Node::~Node()
-{
-}
+Node::~Node() {}
 
 void Node::set_value_type_checked(const shared_ptr<const ValueType>& value_type)
 {
@@ -55,11 +53,16 @@ void Node::assign_tensors()
 {
     vector<std::shared_ptr<const TensorViewType>> tensor_view_types;
     get_value_type()->collect_tensor_views(tensor_view_types);
+    std::shared_ptr<Node> shared_this = shared_from_this();
     size_t i = 0;
     for (auto tvt : tensor_view_types)
     {
-        auto tensor_view_descriptor = make_shared<descriptor::PrimaryTensorView>(tvt, ngraph::descriptor::Tensor::make_tensor_name(this, i), is_output(), is_parameter());
-        m_outputs.emplace_back(this, i, tensor_view_descriptor);
+        auto tensor_view_descriptor = make_shared<descriptor::PrimaryTensorView>(
+            tvt,
+            ngraph::descriptor::Tensor::make_tensor_name(this, i),
+            is_output(),
+            is_parameter());
+        m_outputs.emplace_back(shared_this, i, tensor_view_descriptor);
         i++;
     }
 
@@ -70,7 +73,7 @@ void Node::assign_tensors()
         size_t arg_index = 0;
         for (descriptor::Output& output : arg->get_outputs())
         {
-            m_inputs.emplace_back(this, i, argno, arg_index++, output);
+            m_inputs.emplace_back(shared_this, i, argno, arg_index++, output);
             i++;
         }
         argno++;