added the ability to override the execution end logic (including the part that clears the locals)

Author: GreemDev

src/Lib/Public/Hypervisor/InsnImpl/Starscript.End.cs

@@ -0,0 +1,27 @@
+using System.Runtime.CompilerServices;
+using System.Text;
+
+namespace Starscript;
+
+// ReSharper disable VirtualMemberNeverOverridden.Global
+// ReSharper disable once ClassWithVirtualMembersNeverInherited.Global
+public partial class StarscriptHypervisor
+{
+    protected virtual StringSegment EndExecution(
+        ref StringBuilder sb, 
+        ref StringSegment firstSegment, 
+        ref StringSegment segment, 
+        int index)
+    {
+        if (!_persistentLocals)
+            ClearLocals();
+
+        if (!Unsafe.IsNullRef(ref firstSegment) && !Unsafe.IsNullRef(ref segment))
+        {
+            segment.Next = new StringSegment(index, sb.ToString());
+            return firstSegment;
+        }
+
+        return new StringSegment(index, sb.ToString());
+    }
+}

src/Lib/Public/Hypervisor/Starscript.HV.cs

@@ -1,5 +1,6 @@
 using System.Text;
 using Starscript.Internal;
+using Starscript.Util;
 
 namespace Starscript;
 
@@ -97,7 +98,7 @@ internal StringSegment RunImpl(ExecutableScript script, StringBuilder sb)
 
                 case Instruction.End:
 #if DEBUG
-                    DebugLog($"Encountered {Enum.GetName(Instruction.End)} instruction. Breaking execution.");
+                    DebugLog("End of script code reached. Breaking execution.");
 #endif
 
                     goto EndExecution;
@@ -114,16 +115,7 @@ internal StringSegment RunImpl(ExecutableScript script, StringBuilder sb)
 
         EndExecution:
 
-        if (!_persistentLocals)
-            ClearLocals();
-
-        if (firstSegment != null)
-        {
-            segment!.Next = new StringSegment(index, sb.ToString());
-            return firstSegment;
-        }
-
-        return new StringSegment(index, sb.ToString());
+        return EndExecution(ref sb, ref firstSegment.NullableRef(), ref segment.NullableRef(), index);
     }
 
     private static void AppendValue(StringBuilder sb, Value? value) => sb.Append(value ?? Value.Null);

src/Lib/Public/Starscript.cs

@@ -47,7 +47,7 @@ protected StarscriptHypervisor(ValueMap? globals = null, ValueMap? locals = null
     public static StarscriptException Error([StringSyntax("CompositeFormat")] string format, params object?[] args) 
         => new(args.Length == 0 ? format : string.Format(format, args));
 
-    public StarscriptHypervisor ClearLocals()
+    public virtual StarscriptHypervisor ClearLocals()
     {
         Locals = null;
         return this;

src/Lib/Public/Util/Extensions.cs

@@ -1,9 +1,25 @@
-using System.Text;
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.CompilerServices;
+using System.Text;
 
 namespace Starscript.Util;
 
 public static class Extensions
 {
+    public static ref T NullableRef<T>(this T? value) where T : class
+    {
+        if (value is null)
+            return ref Unsafe.NullRef<T>();
+
+        return ref Unsafe.AsRef(ref value);
+    }
+
+    public static bool TryGetNullableRef<T>(this T? value, out T result) where T : class
+    {
+        result = NullableRef(value);
+        return !Unsafe.IsNullRef(ref result);
+    }
+
     public static string Pluralize(this string word, int quantity, Plurality? plurality = null,
         bool prefixQuantity = false)
     {