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

@@ -32,31 +32,31 @@ 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,
-                  size_t  index,
-                  size_t  argno,
-                  size_t  arg_index,
+            Input(const std::shared_ptr<Node>& node,
+                  size_t index,
+                  size_t argno,
+                  size_t arg_index,
                   Output& output);
 
             std::shared_ptr<Node> get_node();
-            size_t                get_argno() const { return m_argno; }
-            size_t                get_arg_index() const { return m_arg_index; }
-            size_t                get_index() const { return m_index; }
-            const Output&         get_output() const { return m_output; }
-            Output&               get_output() { return m_output; }
-            const Tensor&         get_tensor() const;
-            Tensor&               get_tensor();
+            size_t get_argno() const { return m_argno; }
+            size_t get_arg_index() const { return m_arg_index; }
+            size_t get_index() const { return m_index; }
+            const Output& get_output() const { return m_output; }
+            Output& get_output() { return m_output; }
+            const Tensor& get_tensor() const;
+            Tensor& get_tensor();
 
         protected:
-            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
+            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
             Output& m_output;
 
         private:

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

@@ -32,24 +32,26 @@ 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; }
+            std::shared_ptr<Node> get_node() const;
+            size_t get_index() const { return m_index; }
             std::shared_ptr<TensorView> get_tensor_view() const { return m_tensor_view; }
             void add_input(Input* input);
             const std::set<Input*>& get_inputs() const { return m_inputs; }
-            const Tensor&           get_tensor() const;
-            Tensor&                 get_tensor();
+            const Tensor& get_tensor() const;
+            Tensor& get_tensor();
 
         protected:
-            Node*                       m_node;
-            size_t                      m_index;
+            std::weak_ptr<Node> m_node;
+            size_t m_index;
             std::shared_ptr<TensorView> m_tensor_view;
-            std::set<Input*>            m_inputs;
+            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)
 {
@@ -55,22 +53,27 @@ 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++;
     }
 
-    i            = 0;
+    i = 0;
     size_t argno = 0;
     for (auto arg : get_arguments())
     {
         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++;