wip -- marshal UTF16 string from C# to Rust to avoid GC in C#

csharp_mod/Extensions.cs

@@ -0,0 +1,53 @@
+using System;
+using System.Text;
+using StationeersIC10Editor;
+
+namespace Slang
+{
+    public static unsafe class SlangExtensions
+    {
+        // 1. Convert the Rust Byte Vector (Vec_uint8_t) to a C# String
+        public static string AsString(this Vec_uint8_t vec)
+        {
+            if (vec.ptr == null || vec.len == UIntPtr.Zero)
+            {
+                return string.Empty;
+            }
+
+            // Rust strings are UTF-8. Read bytes from raw pointer.
+            var toReturn = Encoding.UTF8.GetString(vec.ptr, (int)vec.len);
+
+            return toReturn;
+        }
+
+        public static void Drop(this Vec_uint8_t vec)
+        {
+            Ffi.free_string(vec);
+        }
+
+        // 2. Convert Rust Token Vector to C# List
+        public static Line AsList(this Vec_FfiToken_t vec)
+        {
+            var list = new Line();
+            list.Capacity = (int)vec.len;
+
+            var currentPtr = vec.ptr;
+
+            // Iterate through the raw memory array
+            for (int i = 0; i < (int)vec.len; i++)
+            {
+                // Dereference pointer to get the struct at index i
+                FfiToken_t token = currentPtr[i];
+
+                var newToken = new Token(token.text.AsString(), token.column);
+                newToken.Error = token.error.AsString();
+
+                list.Add(newToken);
+            }
+
+            Ffi.free_ffi_token_vec(vec);
+
+            return list;
+        }
+    }
+}