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

csharp_mod/Plugin.cs

@@ -0,0 +1,138 @@
+using System.IO;
+using System.Reflection;
+using System.Text.RegularExpressions;
+using BepInEx;
+using HarmonyLib;
+using StationeersIC10Editor;
+
+namespace Slang
+{
+    class L
+    {
+        private static BepInEx.Logging.ManualLogSource? _logger;
+
+        public static void SetLogger(BepInEx.Logging.ManualLogSource logger)
+        {
+            _logger = logger;
+        }
+
+        public static void Debug(string message)
+        {
+            _logger?.LogDebug(message);
+        }
+
+        public static void Info(string message)
+        {
+            _logger?.LogInfo(message);
+        }
+
+        public static void Error(string message)
+        {
+            _logger?.LogError(message);
+        }
+
+        public static void Warning(string message)
+        {
+            _logger?.LogWarning(message);
+        }
+    }
+
+    [BepInPlugin(PluginGuid, PluginName, "0.1.0")]
+    public class SlangPlugin : BaseUnityPlugin
+    {
+        public const string PluginGuid = "com.biddydev.slang";
+        public const string PluginName = "Slang";
+
+        private static Regex? _slangSourceCheck = null;
+
+        private static Regex SlangSourceCheck
+        {
+            get
+            {
+                if (_slangSourceCheck is null)
+                {
+                    _slangSourceCheck = new Regex(@"[;{}()]|\b(let|fn|device)\b|\/\/");
+                }
+
+                return _slangSourceCheck;
+            }
+        }
+
+        public static unsafe string Compile(string source)
+        {
+            if (string.IsNullOrEmpty(source))
+                return "";
+
+            // Add a null terminator char at the end of the source string (turns into a CStr)
+            source += "\0";
+
+            var bytes = System.Text.Encoding.UTF8.GetBytes(source);
+
+            // don't move my memory around, C#!
+            fixed (byte* pBytes = bytes)
+            {
+                var compiled = Ffi.compile_from_string(pBytes);
+                try
+                {
+                    return compiled.AsString();
+                }
+                finally
+                {
+                    Ffi.free_string(compiled);
+                }
+            }
+        }
+
+        /// <summary>Take original slang source code and copies it to a file
+        /// for use in restoring later.
+        /// </summary>
+        public static bool CopySourceToFile(string source)
+        {
+            return true;
+        }
+
+        public static bool IsSlangSource(ref string input)
+        {
+            return SlangSourceCheck.IsMatch(input);
+        }
+
+        private void Awake()
+        {
+            L.SetLogger(Logger);
+            ExtractNativeDll("slang.dll");
+            var harmony = new Harmony(PluginGuid);
+            harmony.PatchAll();
+            CodeFormatters.RegisterFormatter("slang", () => new SlangFormatter(), true);
+        }
+
+        private void ExtractNativeDll(string fileName)
+        {
+            string destinationPath = Path.Combine(Path.GetDirectoryName(Info.Location), fileName);
+
+            Assembly assembly = Assembly.GetExecutingAssembly();
+
+            using (Stream stream = assembly.GetManifestResourceStream(fileName))
+            {
+                if (stream == null)
+                {
+                    L.Error(
+                        "slang.dll compiler not found. This means it was not embedded in the mod. Please contact the mod author!"
+                    );
+                    return;
+                }
+
+                try
+                {
+                    using (FileStream fileStream = new FileStream(destinationPath, FileMode.Create))
+                    {
+                        stream.CopyTo(fileStream);
+                    }
+                }
+                catch (IOException e)
+                {
+                    L.Warning($"Could not overwrite {fileName} (it might be in use): {e.Message}");
+                }
+            }
+        }
+    }
+}