Made internal collection of graph a list.

src/TensorFlowNET.Core/APIs/tf.variable.cs

@@ -23,14 +23,14 @@ namespace Tensorflow
     {
         public VariableV1[] global_variables(string scope = null)
         {
-            return (ops.get_collection(tf.GraphKeys.GLOBAL_VARIABLES, scope) as List<VariableV1>)
+            return (ops.get_collection<VariableV1>(tf.GraphKeys.GLOBAL_VARIABLES, scope))
                 .ToArray();
         }
 
         public Operation global_variables_initializer()
         {
             var g = variables.global_variables();
-            return variables.variables_initializer(g.ToArray());
+            return variables.variables_initializer(g?.ToArray());
         }
 
         /// <summary>

src/TensorFlowNET.Core/Framework/meta_graph.cs

@@ -264,26 +264,22 @@ namespace Tensorflow
             if (!meta_graph_def.CollectionDef.ContainsKey(key))
                 meta_graph_def.CollectionDef[key] = new CollectionDef();
             var col_def = meta_graph_def.CollectionDef[key];
-
-            switch (graph.get_collection(key))
+            col_def.NodeList = new Types.NodeList();
+            col_def.BytesList = new Types.BytesList();
+            foreach (object value in graph.get_collection(key))
             {
-                case List<RefVariable> collection_list:
-                    col_def.BytesList = new Types.BytesList();
-                    foreach (var x in collection_list)
-                    {
+                switch (value)
+                {
+                    case RefVariable x:
                         var proto = x.to_proto(export_scope);
                         col_def.BytesList.Value.Add(proto.ToByteString());
-                    }
-                    
-                    break;
-                case List<object> collection_list:
-                    col_def.NodeList = new Types.NodeList();
-                    foreach (var x in collection_list)
-                        if (x is ITensorOrOperation x2)
-                            col_def.NodeList.Value.Add(ops.strip_name_scope(x2.name, export_scope));
-                    break;
-                case List<Operation> collection_list:
-                    break;
+                        break;
+                    case ITensorOrOperation x2:
+                        col_def.NodeList.Value.Add(ops.strip_name_scope(x2.name, export_scope));
+                        break;
+                    default:
+                        break;
+                }
             }
         }
 

src/TensorFlowNET.Core/Graphs/Graph.cs

@@ -100,10 +100,12 @@ namespace Tensorflow
         /// </summary>
         private bool _finalized = false;
 
+
         /// <summary>
-        /// Arbitrary collections of objects.
+        /// Arbitrary collections of objects inside the graph.
+        /// TODO: Access might be slow (-> O(n)) depending on size.
         /// </summary>
-        private Dictionary<string, object> _collections = new Dictionary<string, object>();
+        private readonly ICollection<(string name, string scope, object item)> _collections = new List<(string name, string scope, object item)>();
 
         public bool building_function;
         
@@ -228,16 +230,14 @@ namespace Tensorflow
             throw new Exception($"Can not convert a {obj.GetType().Name} into a {types_str}.");
         }
 
-        public void add_to_collection<T>(string name, T value)
+        public void add_to_collection(string name, object value)
         {
             _check_not_finalized();
-            if (_collections.ContainsKey(name))
-                (_collections[name] as List<T>).Add(value);
-            else
-                _collections[name] = new List<T> { value };
+            _collections.Add((name, null, value));
         }
 
-        public void add_to_collections<T>(List<string> names, T value)
+
+        public void add_to_collections(List<string> names, object value)
         {
             foreach (string name in names)
                 add_to_collection(name, value);
@@ -278,12 +278,6 @@ namespace Tensorflow
 
             _create_op_helper(op, true);
 
-            /*Console.Write($"create_op: {op_type} '{node_def.Name}'");
-            Console.Write($", inputs: {(inputs.Length == 0 ? "empty" : String.Join(", ", inputs.Select(x => x.name)))}");
-            Console.Write($", control_inputs: {(control_inputs.Length == 0 ? "empty" : String.Join(", ", control_inputs.Select(x => x.name)))}");
-            Console.Write($", outputs: {(op.outputs.Length == 0 ? "empty" : String.Join(", ", op.outputs.Select(x => x.name)))}");
-            Console.WriteLine();*/
-
             return op;
         }
 
@@ -422,46 +416,29 @@ namespace Tensorflow
 
         public string[] get_all_collection_keys()
         {
-            return _collections.Keys.Where(x => !x.StartsWith("__")).ToArray();
+            return (from c in _collections where !c.name.StartsWith("__") select c.name).ToArray();
         }
 
-        public object get_collection(string name, string scope = null)
+        public List<object> get_collection(string name, string scope = null)
         {
-            return _collections.ContainsKey(name) ? _collections[name] : null;
-        }
-
+            return get_collection<object>(name, scope);
+        }
+
+        private IEnumerable<object> findObjects(string name, string scope)
+        {
+            return (from c in _collections where c.name == name && (scope == null || c.scope == scope) select c.item);
+        }
+
         public List<T> get_collection<T>(string name, string scope = null)
         {
-            List<T> t = default;
-            var collection = _collections.ContainsKey(name) ? _collections[name] : new List<T>();
-            switch (collection)
-            {
-                case List<VariableV1> list:
-                    t = list.Select(x => (T)(object)x).ToList();
-                    break;
-                case List<ResourceVariable> list:
-                    t = list.Select(x => (T)(object)x).ToList();
-                    break;
-                case List<RefVariable> list:
-                    t = list.Select(x => (T)(object)x).ToList();
-                    break;
-                case List<Tensor> list:
-                    t = list.Select(x => (T)(object)x).ToList();
-                    break;
-                case List<Operation> list:
-                    t = list.Select(x => (T)(object)x).ToList();
-                    break;
-                default:
-                    throw new NotImplementedException($"get_collection<{typeof(T).FullName}>");
-            }
-            return t;
+           
+           return (from c in findObjects(name, scope) where c.GetType().IsSubclassOf(typeof(T)) select (T)c).ToList();
+                   
         }
 
         public List<T> get_collection_ref<T>(string name)
         {
-            if (!_collections.ContainsKey(name))
-                _collections[name] = new List<T>();
-            return _collections[name] as List<T>;
+            return get_collection<T>(name);
         }
 
         public void prevent_feeding(Tensor tensor)

src/TensorFlowNET.Core/Summaries/Summary.cs

@@ -39,11 +39,8 @@ namespace Tensorflow.Summaries
 
         public Tensor merge_all(string key = "summaries", string scope= null, string name= null)
         {
-            var summary_ops = ops.get_collection(key, scope: scope);
-            if (summary_ops == null)
-                return null;
-            else
-                return merge((summary_ops as List<ITensorOrOperation>).Select(x => x as Tensor).ToArray(), name: name);
+            var summary_ops = ops.get_collection<ITensorOrOperation>(key, scope: scope);
+            return merge(summary_ops.Select(x => x as Tensor).ToArray(), name: name);
         }
 
         /// <summary>

src/TensorFlowNET.Core/Variables/variable_scope.py.cs

@@ -215,13 +215,13 @@ namespace Tensorflow
 
         public static _VariableStore _get_default_variable_store()
         {
-            var store = ops.get_collection(_VARSTORE_KEY);
-            if (store != null)
-                return (store as List<_VariableStore>)[0];
-
-            var store1 = new _VariableStore();
-            ops.add_to_collection(_VARSTORE_KEY, store1);
-            return store1;
+            var store = ops.get_collection<_VariableStore>(_VARSTORE_KEY).FirstOrDefault();
+            if (store == null)
+            {
+                store = new _VariableStore();
+                ops.add_to_collection(_VARSTORE_KEY, store);
+            }
+            return store;
         }
 
         public static VariableScope get_variable_scope()
@@ -229,32 +229,19 @@ namespace Tensorflow
             return get_variable_scope_store().current_scope;
         }
 
+
+        // TODO: Misses RefVariable as possible value type?
         public static _VariableScopeStore get_variable_scope_store()
         {
-            _VariableScopeStore ret = null;
-            var scope_store = ops.get_collection(_VARSCOPESTORE_KEY);
+            var scope_store = ops.get_collection<_VariableScopeStore>(_VARSCOPESTORE_KEY).FirstOrDefault();
+            if (scope_store == null)
+                scope_store = ops.get_collection<RefVariable>(_VARSCOPESTORE_KEY).FirstOrDefault();
             if (scope_store == null)
             {
-                ret = new _VariableScopeStore();
-                ops.add_to_collection(_VARSCOPESTORE_KEY, ret);
-            }
-            else
-            {
-                switch (scope_store)
-                {
-                    case List<RefVariable> values:
-                        ret = values[0];
-                        break;
-                    case List<_VariableScopeStore> values:
-                        ret = values[0];
-                        break;
-                    default:
-                        throw new InvalidOperationException("get_variable_scope_store");
-                }
-                
+                scope_store = new _VariableScopeStore();
+                ops.add_to_collection(_VARSCOPESTORE_KEY, scope_store);
             }
-
-            return ret;
+            return scope_store;
         }
 
         public static bool _get_trainable_value(VariableSynchronization synchronization, bool? trainable = true)

src/TensorFlowNET.Core/Variables/variables.py.cs

@@ -41,13 +41,8 @@ namespace Tensorflow
         {
             var all = new List<VariableV1>();
 
-            var collection = ops.get_collection(tf.GraphKeys.GLOBAL_VARIABLES, scope);
-            if(collection != null)
-                all.AddRange(collection as List<VariableV1>);
-
-            collection = ops.get_collection(tf.GraphKeys.SAVEABLE_OBJECTS, scope);
-            if (collection != null)
-                all.AddRange(collection as List<VariableV1>);
+            all.AddRange(ops.get_collection<VariableV1>(tf.GraphKeys.GLOBAL_VARIABLES, scope));
+            all.AddRange(ops.get_collection<VariableV1>(tf.GraphKeys.SAVEABLE_OBJECTS, scope));
 
             return all.ToArray();
         }
@@ -65,9 +60,8 @@ namespace Tensorflow
         /// <returns>A list of `Variable` objects.</returns>
         public static List<VariableV1> global_variables(string scope = null)
         {
-            var result = ops.get_collection(tf.GraphKeys.GLOBAL_VARIABLES, scope);
+            return ops.get_collection<VariableV1>(tf.GraphKeys.GLOBAL_VARIABLES, scope);
 
-            return result == null ? new List<VariableV1>() : result as List<VariableV1>;
         }
 
         /// <summary>

src/TensorFlowNET.Core/ops.cs

@@ -63,7 +63,7 @@ namespace Tensorflow
         /// list contains the values in the order under which they were
         /// collected.
         /// </returns>
-        public static object get_collection(string key, string scope = null)
+        public static List<object> get_collection(string key, string scope = null)
         {
             return get_default_graph().get_collection(key, scope);
         }

test/TensorFlowNET.UnitTest/Keras/EmbeddingTest.cs

@@ -14,7 +14,6 @@ namespace TensorFlowNET.UnitTest.Keras
     [TestClass]
     public class EmbeddingTest
     {
-        [Ignore]
         [TestMethod]
         public void Embedding()
         {

test/TensorFlowNET.UnitTest/VariableTest.cs

@@ -1,4 +1,5 @@
-using Microsoft.VisualStudio.TestTools.UnitTesting;
+using FluentAssertions;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 using NumSharp;
 using Tensorflow;
 using static Tensorflow.Binding;
@@ -41,7 +42,7 @@ namespace TensorFlowNET.UnitTest
                 tf_with(tf.variable_scope("bar"), delegate
                 {
                     var v = tf.get_variable("v", new TensorShape(1));
-                    Assert.AreEqual(v.name, "foo/bar/v:0");
+                    v.name.Should().Be("foo/bar/v:0");
                 });
             });
         }