From 70f873eccef99e4ca6af39a8ac798cc36292ace2 Mon Sep 17 00:00:00 2001
From: Haiping Chen <haiping008@gmail.com>
Date: Mon, 10 Jul 2023 15:02:39 -0500
Subject: [PATCH] Initially adding KerasTensor. #1142

---
 src/TensorFlowNET.Core/GlobalUsing.cs         |  4 +-
 .../Keras/Layers/ILayersApi.cs                |  3 +-
 src/TensorFlowNET.Core/Tensors/KerasTensor.cs | 40 +++++++++++++++++++
 src/TensorFlowNET.Keras/BackendImpl.cs        |  2 +-
 src/TensorFlowNET.Keras/GlobalUsing.cs        |  3 +-
 src/TensorFlowNET.Keras/Layers/LayersApi.cs   |  2 +-
 6 files changed, 49 insertions(+), 5 deletions(-)
 create mode 100644 src/TensorFlowNET.Core/Tensors/KerasTensor.cs

diff --git a/src/TensorFlowNET.Core/GlobalUsing.cs b/src/TensorFlowNET.Core/GlobalUsing.cs
index 2fd5b437..209bc291 100644
--- a/src/TensorFlowNET.Core/GlobalUsing.cs
+++ b/src/TensorFlowNET.Core/GlobalUsing.cs
@@ -3,4 +3,6 @@ global using System.Collections.Generic;
 global using System.Text;
 global using System.Collections;
 global using System.Data;
-global using System.Linq;
\ No newline at end of file
+global using System.Linq;
+global using Tensorflow.Keras.Engine;
+global using Tensorflow.Framework.Models;
\ No newline at end of file
diff --git a/src/TensorFlowNET.Core/Keras/Layers/ILayersApi.cs b/src/TensorFlowNET.Core/Keras/Layers/ILayersApi.cs
index 9bc99701..b48cd553 100644
--- a/src/TensorFlowNET.Core/Keras/Layers/ILayersApi.cs
+++ b/src/TensorFlowNET.Core/Keras/Layers/ILayersApi.cs
@@ -1,5 +1,6 @@
 using System;
 using Tensorflow.Framework.Models;
+using Tensorflow.Keras.Engine;
 using Tensorflow.Keras.Layers.Rnn;
 using Tensorflow.NumPy;
 using static Google.Protobuf.Reflection.FieldDescriptorProto.Types;
@@ -135,7 +136,7 @@ namespace Tensorflow.Keras.Layers
         public ILayer GlobalMaxPooling1D(string data_format = "channels_last");
         public ILayer GlobalMaxPooling2D(string data_format = "channels_last");
 
-        public Tensors Input(Shape shape = null,
+        public KerasTensor Input(Shape shape = null,
             int batch_size = -1,
             string name = null,
             TF_DataType dtype = TF_DataType.DtInvalid,
diff --git a/src/TensorFlowNET.Core/Tensors/KerasTensor.cs b/src/TensorFlowNET.Core/Tensors/KerasTensor.cs
new file mode 100644
index 00000000..1034dcc8
--- /dev/null
+++ b/src/TensorFlowNET.Core/Tensors/KerasTensor.cs
@@ -0,0 +1,40 @@
+namespace Tensorflow.Keras.Engine;
+
+/// <summary>
+/// A representation of a Keras in/output during Functional API construction.
+/// </summary>
+public class KerasTensor
+{
+    private Tensor _tensor;
+    public void SetTensor(Tensors tensor) 
+        => _tensor = tensor;
+
+    private TensorSpec _type_spec;
+    private string _name;
+
+    public KerasTensor(TensorSpec type_spec, string name = null)
+    {
+        _type_spec = type_spec;
+        _name = name;
+    }
+
+    public static KerasTensor from_tensor(Tensor tensor)
+    {
+        var type_spec = tensor.ToTensorSpec();
+        var kt = new KerasTensor(type_spec, name: tensor.name);
+        kt.SetTensor(tensor);
+        return kt;
+    }
+
+    public static implicit operator Tensors(KerasTensor kt)
+        => kt._tensor;
+
+    public static implicit operator Tensor(KerasTensor kt)
+        => kt._tensor;
+
+    public static implicit operator KerasTensor(Tensor tensor)
+        => from_tensor(tensor);
+
+    public static implicit operator KerasTensor(Tensors tensors)
+        => from_tensor(tensors.First());
+}
diff --git a/src/TensorFlowNET.Keras/BackendImpl.cs b/src/TensorFlowNET.Keras/BackendImpl.cs
index 364800ae..574cf599 100644
--- a/src/TensorFlowNET.Keras/BackendImpl.cs
+++ b/src/TensorFlowNET.Keras/BackendImpl.cs
@@ -76,7 +76,7 @@ namespace Tensorflow.Keras
             _GRAPH_VARIABLES[graph.graph_key] = v;
         }
 
-        public Tensor placeholder(Shape shape = null,
+        public KerasTensor placeholder(Shape shape = null,
             int ndim = -1,
             TF_DataType dtype = TF_DataType.DtInvalid,
             bool sparse = false,
diff --git a/src/TensorFlowNET.Keras/GlobalUsing.cs b/src/TensorFlowNET.Keras/GlobalUsing.cs
index bc0798ed..85cd9194 100644
--- a/src/TensorFlowNET.Keras/GlobalUsing.cs
+++ b/src/TensorFlowNET.Keras/GlobalUsing.cs
@@ -4,4 +4,5 @@ global using System.Text;
 global using System.Linq;
 global using static Tensorflow.Binding;
 global using static Tensorflow.KerasApi;
-global using Tensorflow.NumPy;
\ No newline at end of file
+global using Tensorflow.NumPy;
+global using Tensorflow.Keras.Engine;
\ No newline at end of file
diff --git a/src/TensorFlowNET.Keras/Layers/LayersApi.cs b/src/TensorFlowNET.Keras/Layers/LayersApi.cs
index 213b53a8..5968461d 100644
--- a/src/TensorFlowNET.Keras/Layers/LayersApi.cs
+++ b/src/TensorFlowNET.Keras/Layers/LayersApi.cs
@@ -466,7 +466,7 @@ namespace Tensorflow.Keras.Layers
         /// In this case, values of 'None' in the 'shape' argument represent ragged dimensions. For more information about RaggedTensors, see this guide.
         /// </param>
         /// <returns>A tensor.</returns>
-        public Tensors Input(Shape shape = null,
+        public KerasTensor Input(Shape shape = null,
             int batch_size = -1,
             string name = null,
             TF_DataType dtype = TF_DataType.DtInvalid,