From 4aa1df0628c5d531b518691eb8ab22b907946eb0 Mon Sep 17 00:00:00 2001
From: Roland Grinis <roland.grinis@grinisrit.com>
Date: Tue, 2 Mar 2021 09:32:36 +0000
Subject: [PATCH] Safe item method and view_as added

---
 .../space/kscience/kmath/tensors/RealTensorAlgebra.kt  | 10 +++++++++-
 .../space/kscience/kmath/tensors/TensorAlgebra.kt      |  1 +
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/tensors/RealTensorAlgebra.kt b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/tensors/RealTensorAlgebra.kt
index 6023d2b72..24612a6aa 100644
--- a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/tensors/RealTensorAlgebra.kt
+++ b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/tensors/RealTensorAlgebra.kt
@@ -14,9 +14,13 @@ public class RealTensor(
         TensorStrides(shape),
         RealBuffer(buffer)
     ) {
-    override fun item(): Double = buffer[0]
+    override fun item(): Double {
+        check(buffer.size > 0) { "The tensor is empty" }
+        return buffer[0]
+    }
 }
 
+
 public class RealTensorAlgebra : TensorPartialDivisionAlgebra<Double, RealTensor> {
 
     override fun Double.plus(other: RealTensor): RealTensor {
@@ -116,6 +120,10 @@ public class RealTensorAlgebra : TensorPartialDivisionAlgebra<Double, RealTensor
         TODO("Not yet implemented")
     }
 
+    override fun RealTensor.view_as(other: RealTensor): RealTensor {
+        TODO("Not yet implemented")
+    }
+
     override fun RealTensor.abs(): RealTensor {
         TODO("Not yet implemented")
     }
diff --git a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/tensors/TensorAlgebra.kt b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/tensors/TensorAlgebra.kt
index 137230d29..cddda7670 100644
--- a/kmath-core/src/commonMain/kotlin/space/kscience/kmath/tensors/TensorAlgebra.kt
+++ b/kmath-core/src/commonMain/kotlin/space/kscience/kmath/tensors/TensorAlgebra.kt
@@ -40,6 +40,7 @@ public interface TensorAlgebra<T, TensorType : TensorStructure<T>>{
 
     //https://pytorch.org/docs/stable/tensor_view.html
     public fun TensorType.view(shape: IntArray): TensorType
+    public fun TensorType.view_as(other: TensorType): TensorType
 
     //https://pytorch.org/docs/stable/generated/torch.abs.html
     public fun TensorType.abs(): TensorType