From 80d321a0f728167376ac3f6a88b5ad0ee1eeda09 Mon Sep 17 00:00:00 2001
From: Craig Long <craig.alan.long@gmail.com>
Date: Tue, 7 Jun 2022 13:44:42 -0400
Subject: [PATCH] GraphicDataProvider Fix: Regression for pointer referencing
 non-clr objects (#12934)

* Fix regression for pointer object referencing non-clr objects

* Update comments

* Add test

Co-authored-by: Craig Long <craig.long@autodesk.com>
---
 src/Engine/ProtoCore/ClassTable.cs            | 10 ++++++++
 .../Reflection/GraphicDataProvider.cs         | 23 +++++++++++--------
 test/DynamoCoreTests/Nodes/ListTests.cs       | 13 +++++++++++
 3 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/src/Engine/ProtoCore/ClassTable.cs b/src/Engine/ProtoCore/ClassTable.cs
index 5dddb2ec734..dd55446d686 100644
--- a/src/Engine/ProtoCore/ClassTable.cs
+++ b/src/Engine/ProtoCore/ClassTable.cs
@@ -494,6 +494,16 @@ public void SetClassNodeAt(ClassNode node, int index)
             symbol.Id = index;
         }
 
+        /// <summary>
+        /// Retreive the ClassNode at the index.  
+        /// </summary>
+        /// <param name="index"></param>
+        /// <returns>ClassNode if found, else null value</returns>
+        internal ClassNode GetClassNodeAtIndex(int index)
+        {
+            return index >= 0 && index < classNodes.Count ? classNodes[index] : null;
+        }
+
         /// <summary>
         /// Find a matching class for given partial class name.
         /// </summary>
diff --git a/src/Engine/ProtoCore/Reflection/GraphicDataProvider.cs b/src/Engine/ProtoCore/Reflection/GraphicDataProvider.cs
index dce211006b3..80602067e8f 100644
--- a/src/Engine/ProtoCore/Reflection/GraphicDataProvider.cs
+++ b/src/Engine/ProtoCore/Reflection/GraphicDataProvider.cs
@@ -147,21 +147,24 @@ internal List<IGraphicItem> GetGraphicItems(DSASM.StackValue svData, RuntimeCore
         
         internal object GetCLRObject(StackValue svData, RuntimeCore runtimeCore)
         {
-            if (marshaler != null)
-            {
-                return marshaler.UnMarshal(svData, null, interpreter, typeof(object));
-            }
-            
             if (null == runtimeCore.DSExecutable.classTable)
                 return null;
 
-            IList<ClassNode> classNodes = runtimeCore.DSExecutable.classTable.ClassNodes;
-            if (null == classNodes || (classNodes.Count <= 0))
+            //The GetCLRObject function is typically utilized to retrieve a ClrObject from a StackValue of type pointer.
+            //There is an edge cases for pointers where the pointer references a non CLR object.  This code
+            //checks for this edge case by verifying that the requested StackValue pointer is associated with an
+            //imported library.  An example is the "Function" pointer which does not have an associated CLRObject.
+            //In that case, the return value should be null.
+            var classNode = runtimeCore.DSExecutable.classTable.GetClassNodeAtIndex(svData.metaData.type);
+            if (classNode != null  && !classNode.IsImportedClass)
+            {
                 return null;
+            }
 
-            ClassNode classnode = runtimeCore.DSExecutable.classTable.ClassNodes[svData.metaData.type];
-            if (!classnode.IsImportedClass) //TODO: look at properties to see if it contains any FFI objects.
-                return null;
+            if (marshaler != null)
+            {
+                return marshaler.UnMarshal(svData, null, interpreter, typeof(object));
+            }
 
             try
             {
diff --git a/test/DynamoCoreTests/Nodes/ListTests.cs b/test/DynamoCoreTests/Nodes/ListTests.cs
index b85456dbc32..07e7c389d99 100644
--- a/test/DynamoCoreTests/Nodes/ListTests.cs
+++ b/test/DynamoCoreTests/Nodes/ListTests.cs
@@ -665,6 +665,19 @@ public void SortBy_SimpleTest()
 		}
 
         [Test]
+        public void SortBy_PreviewValueIsCorrectForFunction()
+        {
+            string openPath = Path.Combine(TestDirectory, @"core\list\SortBy_SimpleTest.dyn");
+            RunModel(openPath);
+
+            var preview = GetPreviewValueInString("42ac0cec-442f-4e4a-b629-1260f6db3d86");
+            Assert.AreEqual("Function()", preview);
+            
+            var value = GetPreviewValue("42ac0cec-442f-4e4a-b629-1260f6db3d86");
+            Assert.Null(value);
+        }
+
+		[Test]
         public void SortByKey_SimpleTest()
         {
             string openPath = Path.Combine(TestDirectory, @"core\list\ListSortByKey.dyn");