_FetchMapper

src/TensorFlowNET.Core/Graph.cs

@@ -31,6 +31,50 @@ namespace Tensorflow
             _names_in_use = new Dictionary<string, int>();
         }
 
+        public T as_graph_element<T>(T obj, bool allow_tensor = true, bool allow_operation = true)
+        {
+            return _as_graph_element_locked(obj, allow_tensor, allow_operation);
+        }
+
+        private Func<object> _as_graph_element(object obj)
+        {
+            return null;
+        }
+
+        private T _as_graph_element_locked<T>(T obj, bool allow_tensor = true, bool allow_operation = true)
+        {
+            string types_str = "";
+
+            if (allow_tensor && allow_operation)
+            {
+                types_str = "Tensor or Operation";
+            }
+            else if (allow_tensor)
+            {
+                types_str = "Tensor";
+            }
+            else if (allow_operation)
+            {
+                types_str = "Operation";
+            }
+
+            var temp_obj = _as_graph_element(obj);
+
+            if(obj is Tensor && allow_tensor)
+            {
+                if ((obj as Tensor).graph.Equals(this))
+                {
+                    return obj;
+                }
+                else
+                {
+                    throw new Exception($"Tensor {obj} is not an element of this graph.");
+                }
+            }
+
+            throw new Exception($"Can not convert a {typeof(T).Name} into a {types_str}.");
+        }
+
         public unsafe Operation create_op(string op_type, List<Tensor> inputs, TF_DataType[] dtypes, 
             TF_DataType[] input_types = null, string name = "", 
             Dictionary<string, AttrValue> attrs = null, OpDef op_def = null)

src/TensorFlowNET.Core/Operation.cs

@@ -8,6 +8,7 @@ namespace Tensorflow
     public class Operation
     {
         private Graph _graph;
+        public Graph graph => _graph;
         public IntPtr _c_op;
         public int _id => _id_value;
         private int _id_value;

src/TensorFlowNET.Core/Session/_ElementFetchMapper.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Tensorflow
+{
+    /// <summary>
+    /// Fetch mapper for singleton tensors and ops.
+    /// </summary>
+    public class _ElementFetchMapper : _FetchMapper
+    {
+        private List<Object> _unique_fetches = new List<object>();
+        private Action _contraction_fn;
+
+        public _ElementFetchMapper(List<Tensor> fetches, Action contraction_fn)
+        {
+            foreach(var tensor in fetches)
+            {
+                var fetch = ops.get_default_graph().as_graph_element(tensor, allow_tensor: true, allow_operation: true);
+                _unique_fetches.Add(fetch);
+            }
+        }
+    }
+}

src/TensorFlowNET.Core/Session/_FetchHandler.cs

@@ -9,9 +9,11 @@ namespace Tensorflow
     /// </summary>
     public class _FetchHandler
     {
-        public _FetchHandler(Graph graph, Tensor fetches)
-        {
+        private _ElementFetchMapper _fetch_mapper;
 
+        public _FetchHandler(Graph graph, Tensor fetches, object feeds = null, object feed_handles = null)
+        {
+            _fetch_mapper = new _FetchMapper().for_fetch(fetches);
         }
     }
 }

src/TensorFlowNET.Core/Session/_FetchMapper.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Tensorflow
+{
+    public class _FetchMapper
+    {
+        public _ElementFetchMapper for_fetch(Tensor fetch)
+        {
+            var fetches = new List<Tensor> { fetch };
+
+            return new _ElementFetchMapper(fetches, null);
+        }
+    }
+}

src/TensorFlowNET.Core/Tensor.cs

@@ -13,6 +13,8 @@ namespace Tensorflow
         private DataType _dtype;
         public DataType dtype => _dtype;
 
+        public Graph graph => _op.graph;
+
         public string name;
 
         public Tensor(Operation op, int value_index, DataType dtype)